JP2019080917A - Medical X-ray CT imaging apparatus, medical X-ray CT imaging condition setting method, and X-ray CT imaging condition setting program - Google Patents

Abstract

To acquire an X-ray CT image having quality as appropriate as possible according to an imaging purpose while achieving low exposure as much as possible.SOLUTION: A medical X-ray CT imaging apparatus includes: an X-ray generator 22 for generating a cone beam; an X-ray detector 24; a support unit 20 for supporting the X-ray generator 22 and the X-ray detector 24 in a state that they face each other; a turning driving part 30 for turning the X-ray generator 22 and the X-ray detector 24 supported by the support unit 20; an imaging information reception unit 40 for receiving settings of an imaging region on at least one of a size of an imaging region, an imaging purpose, and an imaging site; and an X-ray output condition setting unit 60 for automatically setting an output condition of the X-ray generator 22 according to at least one of the size of the imaging region, the imaging purpose, and the imaging site received by the imaging information reception unit 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for setting imaging conditions in a medical X-ray CT imaging apparatus.

  Patent Document 1 discloses that an adult input or an infant input is performed and the age of the patient is input depending on whether the patient is an adult or an infant. Further, Patent Document 2 also discloses performing top priority target input such as exposure dose, image quality or imaging speed. In the X-ray CT imaging apparatus of Patent Document 1, it is disclosed that optimum imaging conditions are automatically set based on an adult / infant input and a top priority target input.

  Patent Document 2 discloses that CT scan parameters are derived in accordance with the physique of a patient.

Japanese Patent Application Publication No. 2005-80748 Japanese Patent Application Publication No. 2014-528284

  When performing X-ray CT imaging, it is preferable to reduce exposure as much as possible.

  However, it may not be possible to obtain an appropriate CT image according to the diagnostic purpose by setting the imaging conditions according to the adult or the infant or the physical constitution. For example, even when performing X-ray CT imaging for an infant or a person with a small physical size, it may be desirable to obtain a clear X-ray CT image of a local area. In addition, even when X-ray CT imaging is performed for an adult or a person with a large physical size, it is sufficient if a wide range of X-ray CT images can be obtained, and there is a case where such a degree of sharpness is not required.

  Therefore, an object of the present invention is to make it possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose while achieving as low exposure as possible.

  In order to solve the above problems, a medical X-ray CT imaging apparatus according to a first aspect comprises an X-ray generator generating a cone beam, an X-ray detector, the X-ray generator, and the X-ray detector And a pivot drive unit for pivoting the X-ray generator supported by the support unit and the X-ray detector, the size of the imaging region, the purpose of imaging, and the imaging region. According to at least one of the imaging information reception unit for receiving the setting of the imaging region related to at least one of the imaging region and the size, the imaging purpose, and the imaging region of the imaging region received by the imaging information reception unit. And an X-ray output condition setting unit configured to automatically set an output condition of the line generator.

  A second aspect is the medical X-ray CT imaging apparatus according to the first aspect, wherein the setting of the imaging area received by the imaging information reception unit and the setting of the X-ray output condition setting unit The apparatus further comprises an image quality setting unit that automatically sets the image quality of the X-ray CT image according to at least one of the output conditions of the X-ray generator.

  A third aspect is the medical X-ray CT imaging apparatus according to the first or second aspect, wherein the imaging information receiving unit is configured as the setting related to the size of the imaging region, the pivot shaft by the pivot drive unit Accept the setting of the size of the imaging area in the plane orthogonal to

  A fourth aspect is the medical X-ray CT imaging apparatus according to any one of the first to third aspects, wherein the imaging information reception unit is configured to perform the first imaging as the setting relating to the size of the imaging area. It is possible to receive the setting of the area and the second imaging area wider than the first imaging area, and the X-ray output condition setting unit is based on the second output condition according to the size of the second imaging area. At least one set value defining each of the first output condition and the second output condition such that the dose is smaller than the dose based on the first output condition according to the size of the first imaging region Set automatically.

  A fifth aspect is the medical X-ray CT imaging apparatus according to the fourth aspect, wherein the imaging information reception unit sets the maxillofacial area of the subject as an imaging area as a setting related to the size of the imaging area, It is possible to accept a setting in which an area in which a part of teeth of the dental arch is contained is the first imaging area, and an area in which the entire dental arch or all the teeth of the dental arch are accommodated is the second imaging area.

  A sixth aspect is the medical X-ray CT imaging apparatus according to the fourth aspect, wherein the imaging information reception unit has a diameter of a boundary circle or a circumscribed circle of R1 (mm) as the first imaging region. It is possible to accept the setting of the imaging area and to accept the setting of the imaging area in which the diameter of the boundary circle or the circumscribed circle is R2 (mm) as the second imaging area, where 40 (mm) <k1 (mm) R1 (mm) <k1 (mm) <R2 (mm) is satisfied with respect to the value k1 which satisfies <70 (mm).

  A seventh aspect is the medical X-ray CT imaging apparatus according to the fourth aspect, wherein the imaging information reception unit has a diameter of a boundary circle or a circumscribed circle of R1 (mm) as the first imaging region. It is possible to accept the setting of the imaging area and to accept the setting of the imaging area in which the diameter of the boundary circle or circumscribed circle is R2 (mm) as the second imaging area, where 80 (mm) <k2 (mm) R1 (mm) <k2 (mm) <R2 (mm) to a value k2 that satisfies <120 (mm).

  An eighth aspect is the medical X-ray CT imaging apparatus according to any one of the first to seventh aspects, wherein the imaging information receiving unit is capable of receiving a physical setting, and the X-ray output The condition setting unit adds the size of the imaging area received by the imaging information reception unit, the imaging purpose regarding the imaging purpose and the imaging area regarding at least one of the imaging regions, according to the setting of the physique Automatically setting output conditions of the X-ray generator;

  A ninth aspect is the medical X-ray CT imaging apparatus according to the eighth aspect, wherein the imaging information reception unit is a physical size of a child or a physical size exceeding that of a child as the setting of the physical size The X-ray output condition setting unit receives children's settings, and the X-ray output condition setting unit exceeds children so that the dose based on output conditions according to the physical size exceeding children is larger than the dose based on the output conditions according to children's physical size At least one set value defining each of the output condition according to the physical constitution and the output condition according to the physical constitution of the child is automatically set.

  A tenth aspect is the medical X-ray CT imaging apparatus according to any one of the first to ninth aspects, wherein the imaging information receiving unit receives the setting of the imaging purpose, and the X-ray output condition The setting unit automatically sets the output condition of the X-ray generator according to the imaging purpose received by the imaging information receiving unit.

  An eleventh aspect is the medical X-ray CT imaging apparatus according to any one of the first to tenth aspects, wherein the imaging information receiving unit receives the setting of the imaging region, and the X-ray output condition The setting unit automatically sets the output condition of the X-ray generator according to the imaging region received by the imaging information reception unit.

  A twelfth aspect is the medical X-ray CT imaging apparatus according to any one of the first to eleventh aspects, wherein the X-ray output condition setting unit is configured as the output condition of the X-ray generator. At least one of the tube voltage of the X-ray generator, the tube current, and the time during which the X-ray generator emits X-rays are automatically set.

  A thirteenth aspect is the medical X-ray CT imaging apparatus according to any one of the first to twelfth aspects, further comprising a mode setting reception unit for receiving settings of the low dose mode and the high resolution mode, When the low dose mode is received by the mode setting receiving unit, the X-ray output condition setting unit outputs the output condition of the X-ray generator according to the imaging region received by the imaging information receiving unit. Set automatically.

  A fourteenth aspect is the medical X-ray CT imaging apparatus according to any one of the first to thirteenth aspects, further comprising an output condition setting reception unit that receives manual setting of the output condition of the X-ray generator. The X-ray output condition setting unit automatically sets the output condition of the X-ray generator according to the imaging region received by the imaging information reception unit, and then manually sets the X-ray output condition via the output condition setting reception unit. The output condition of the X-ray generator is changed according to

  According to a fifteenth aspect of the present invention, there is provided an X-ray generator that generates a cone beam, an X-ray detector, and a support unit that supports the X-ray generator and the X-ray detector in an opposing state. In the medical X-ray CT imaging apparatus provided with the X-ray generator supported by the support portion and a pivot drive unit for pivoting the X-ray detector, conditions for performing the X-ray CT imaging are as follows: A medical X-ray CT imaging condition setting method to be set, comprising: receiving the setting of the imaging area regarding at least one of the size of the imaging area, the imaging purpose and the imaging region; the size of the accepted imaging area; The output condition of the X-ray generator is automatically set according to at least one of the purpose and the imaging region.

  Furthermore, in order to solve the above problems, the sixteenth aspect supports an X-ray generator that generates a cone beam, an X-ray detector, the X-ray generator, and the X-ray detector in an opposing state. An X-ray CT imaging condition setting program for a medical X-ray CT imaging apparatus, comprising: a support portion; and a pivot drive portion for pivoting the X-ray generator supported by the support portion and the X-ray detector. (A) receiving the setting of the imaging area regarding at least one of the size of the imaging area, the imaging purpose, and the imaging region to the computer for setting the X-ray CT imaging condition of the medical X-ray CT imaging apparatus; And (b) automatically setting the output condition of the X-ray generator in accordance with at least one of the size of the imaging region, the imaging purpose, and the imaging region received. CT imaging condition setting group A gram.

  Furthermore, in order to solve the above problems, a seventeenth aspect is a medical X-ray CT imaging apparatus, comprising: an X-ray generator that generates a cone beam; an X-ray detector; the X-ray generator; And a processor for supporting the X-ray detector in a facing state, an actuator for pivoting the X-ray generator supported by the support and the X-ray detector, and the processor The size of the area, the purpose of imaging, and the setting of the imaging area regarding at least one of the imaging region are input as imaging information, and the size of the imaging area input when setting the X-ray CT imaging conditions, the imaging purpose, The output condition of the X-ray generator is automatically set according to at least one of the imaging sites.

  An eighteenth aspect is the medical X-ray CT imaging apparatus according to the seventeenth aspect, wherein the processor is configured to set the first imaging area and the first imaging area as the setting relating to the size of the imaging area. It is possible to receive setting information with a wide second imaging area, and a dose based on a second output condition according to the size of the second imaging area is a first output according to the size of the first imaging area At least one set value defining each of the first output condition and the second output condition is automatically set to be smaller than the dose based on the condition.

  A nineteenth aspect is the medical X-ray CT imaging apparatus according to the seventeenth or eighteenth aspect, wherein the processor sets the first imaging purpose and the second imaging purpose as the setting relating to the imaging purpose. The first imaging purpose is an imaging purpose aiming at more detailed observation than the second imaging purpose, and a dose based on a second output condition according to the second imaging purpose is At least one set value defining each of the first output condition and the second output condition is automatically set to be smaller than the dose based on the first output condition according to the first imaging purpose.

  A twentieth aspect is the medical X-ray CT imaging apparatus according to any one of the seventeenth to nineteenth aspects, wherein the processor is configured to set the first imaging region and the second imaging as the setting related to the imaging region. The first imaging site has a larger amount of hard tissue than the second imaging site, or has a higher density of hard tissue than the second imaging site. At least one set value defining each of the first output condition and the second output condition such that the dose based on the output condition is smaller than the dose based on the first output condition according to the first imaging region Set automatically.

  A twenty-first aspect is the medical X-ray CT imaging apparatus according to any one of the seventeenth to twentieth aspects, wherein the processor sets and sets the imaging region inputted. The image quality of the X-ray CT image is automatically set in accordance with at least one of the output conditions of

  According to the first aspect, the exposure condition can be reduced as much as possible by automatically setting the output condition of the X-ray generator according to at least one of the size of the imaging region, the imaging purpose, and the imaging region received. be able to. Also, in general, the size of the imaging area or the imaging site is set according to the imaging purpose, and the output condition of the X-ray generator according to at least one of the imaging area size, the imaging purpose and the imaging site By automatically setting, it is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose.

  In an X-ray output condition aiming at low dose, noise can easily get on the X-ray CT image. Therefore, noise can be reduced by automatically setting the image quality of the X-ray CT image according to at least one of the setting of the imaging region and the output condition of the X-ray generator as in the second aspect.

  According to the third aspect, the output condition of the X-ray generator can be automatically set in accordance with the size in the plane orthogonal to the pivot axis.

  According to the fourth aspect, when the relatively small first imaging region is set, X-ray CT imaging can be performed under the first output condition in which the dose becomes relatively large. On the other hand, when a relatively large second imaging region is set, X-ray CT imaging can be performed under a second output condition in which the dose is relatively small.

  According to the fifth aspect, when a region in which a part of teeth of the dental arch fits is set as the first imaging region, X-ray CT imaging is performed under the first output condition in which the dose becomes relatively large. This enables observation with a relatively clear image. On the other hand, when the whole area of the dental arch or the area in which all the teeth of the dental arch fit is set as the second imaging area, X-ray CT imaging may be performed under the second output condition where the dose is relatively small. it can.

  According to the sixth aspect, based on the value k1 satisfying 40 (mm) <k1 (mm) <70 (mm), when R1 is smaller than that, X1 under the first output condition in which the dose becomes relatively large. Line CT imaging can be performed. For this reason, when performing X-ray CT imaging for a part of the dental arch, observation with a relatively clear image becomes possible. On the other hand, when R2 is larger than k1, X-ray CT imaging can be performed under the second output condition in which the dose is relatively small. Therefore, when performing X-ray CT imaging for the entire dental arch or the like, X-ray CT imaging can be performed with a relatively low dose.

  According to the seventh aspect, based on the value k1 satisfying 80 (mm) <k1 (mm) <120 (mm), when R1 is smaller than that, X1 under the first output condition in which the dose becomes relatively large. Line CT imaging can be performed. For this reason, when performing X-ray CT imaging for the whole dental arch etc., observation with a comparatively clear image becomes possible. On the other hand, when R2 is larger than k1, X-ray CT imaging can be performed under the second output condition in which the dose is relatively small. Therefore, when performing X-ray CT imaging for the entire jaw or the like, X-ray CT imaging can be performed with a relatively low dose.

  According to the eighth aspect, the X-ray output condition setting unit generates the X-ray according to at least one of the physical constitution, the imaging purpose, and the imaging region in addition to the imaging region received by the imaging information reception unit. Automatically set the output conditions of the Thereby, the exposure can be reduced as much as possible in consideration of at least one of the physical constitution, the imaging purpose, and the imaging region. In addition, an X-ray CT image of appropriate image quality can be obtained in consideration of at least one of physical constitution, imaging purpose, and imaging site.

  According to the ninth aspect, when it is set that the subject is the physical size of a child as the setting of the physical size, the dose can be reduced and the exposure dose can be reduced. On the other hand, if it is set that the physical size exceeds children, the dose can be increased to obtain a clear image.

  According to the tenth aspect, the output condition of the X-ray generator can be automatically set according to the set imaging purpose.

  According to the eleventh aspect, the output condition of the X-ray generator can be automatically set in accordance with the set imaging site.

  According to the twelfth aspect, by setting at least one of the tube voltage of the X-ray generator, the tube current, and the time during which the X-ray generator emits X-rays, it is possible to adjust the dose and the like.

  According to the thirteenth aspect, when the low dose mode is accepted, the output condition of the X-ray generator is automatically set in accordance with the accepted imaging area, thereby achieving as low exposure as possible for the purpose of imaging. Accordingly, an X-ray CT image of appropriate image quality can be obtained.

  According to the fourteenth aspect, the output condition of the X-ray generator set in accordance with the imaging region can be changed by manual setting in accordance with the preference of the operator.

  According to the fifteenth aspect, the exposure condition can be reduced as much as possible by automatically setting the output condition of the X-ray generator in accordance with at least one of the size of the imaging region received, the imaging purpose, and the imaging region. be able to. Also, normally, the size of the imaging area and the imaging site are set according to the imaging purpose, and the output condition of the X-ray generator according to at least one of the size of the imaging area, the imaging purpose and the imaging site By automatically setting, it is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose.

  According to the sixteenth aspect, the exposure condition can be reduced as much as possible by automatically setting the output condition of the X-ray generator in accordance with at least one of the size of the imaging region, the imaging purpose, and the imaging region received. be able to. Also, normally, the size of the imaging area and the imaging site are set according to the imaging purpose, and the output condition of the X-ray generator according to at least one of the size of the imaging area, the imaging purpose and the imaging site By automatically setting, it is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose.

  According to the seventeenth aspect, the exposure condition can be reduced as much as possible by automatically setting the output condition of the X-ray generator according to at least one of the size of the imaging region, the imaging purpose, and the imaging region. it can. Also, in general, the size of the imaging area or the imaging site is set according to the imaging purpose, and the output condition of the X-ray generator according to at least one of the imaging area size, the imaging purpose and the imaging site By automatically setting, it is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose.

  According to the eighteenth aspect, when the relatively small first imaging region is set, X-ray CT imaging can be performed under the first output condition in which the dose becomes relatively large. On the other hand, when a relatively large second imaging region is set, X-ray CT imaging can be performed under a second output condition in which the dose is relatively small.

  According to the nineteenth aspect, the output conditions of the X-ray generator can be automatically set in accordance with the set imaging purpose.

  According to the twentieth aspect, the output condition of the X-ray generator can be automatically set in accordance with the imaging site where the amount of the amount of hard tissue is different.

  In an X-ray output condition aiming at low dose, noise can easily get on the X-ray CT image. Therefore, as in the twenty-first aspect, noise is automatically set by automatically setting the image quality of the X-ray CT image according to at least one of the setting of the input imaging region and the set output condition of the X-ray generator. Can be reduced.

1 is a schematic view showing an X-ray CT imaging apparatus according to a first embodiment. It is a flowchart which shows the process by a X-ray output condition setting part. It is a general view which shows the structure of the X-ray CT imaging apparatus which concerns on 2nd Embodiment. It is a perspective view when the X-ray CT imaging apparatus concerning 2nd Embodiment is seen from diagonally upward. It is a functional block diagram of X-ray CT imaging device. It is a block diagram which shows the electric constitution of a main body control part. It is a figure which shows the example of a display of an operating panel apparatus. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows an example of a reference table. It is a flowchart which shows the process example of a X-ray CT imaging apparatus. It is a figure which shows the other example of a reference table. It is a figure which shows the example of a display for a setting of an operating panel apparatus. It is a figure which shows the other example of a reference table. It is a figure which shows the other example of a reference table. It is a figure which shows the other example of a reference table.

First Embodiment
Hereinafter, a medical X-ray CT imaging apparatus, a medical X-ray CT imaging apparatus, a medical X-ray CT imaging condition setting method, and an X-ray CT imaging condition setting program according to the first embodiment will be described. FIG. 1 is a schematic view showing an X-ray CT imaging apparatus 10.

  The X-ray CT imaging apparatus 10 is an apparatus for performing X-ray CT (Computed Tomography) imaging of a subject P, and includes an X-ray generator 22, an X-ray detector 24, a support unit 20, and a turning drive unit 30. The imaging information receiving unit 40 and the X-ray output condition setting unit 60 are provided.

  The x-ray generator 22 generates an x-ray cone beam. The X-ray detector 24 detects an X-ray cone beam emitted from the X-ray generator 22.

  The support unit 20 supports the X-ray generator 22 and the X-ray detector 24 in an opposing state. In a state where the X-ray generator 22 and the X-ray detector 24 are supported by the support portion 20, an interval at which the subject P can be disposed is provided therebetween. The subject P is, for example, a human head. Then, the X-ray cone beam emitted from the X-ray generator 22 passes through the subject P and enters the X-ray detector 24. The X-ray incident on the X-ray detector 24 is converted into an electrical signal corresponding to the intensity of the X-ray for each unit pixel. An X-ray CT image or the like is generated based on the respective electrical signals.

  The pivot drive unit 30 pivots the X-ray generator 22 and the X-ray detector 24 supported by the support unit 20. For example, the turning drive unit 30 includes an electric motor, and as necessary, includes an acceleration / deceleration mechanism such as a gear. The swing drive unit 30 rotatably supports an axial portion 33 protruding from the support unit 20 at a position between the X-ray generator 22 and the X-ray detector 24. The support portion 20 is pivoted by the drive of the pivot drive portion 30 with the central axis of the shaft portion 33 as the pivot center. Along with this, the X-ray generator 22 and the X-ray detector 24 turn around the subject P.

  The imaging information reception unit 40 is configured to be able to receive the setting of the imaging area. For example, the imaging information receiving unit 40 can adopt a configuration for accepting the setting of the imaging area by accepting an input operation by the operator through a touch panel, an operation switch, or the like.

  The setting of the imaging region includes information regarding at least one of the size of the imaging region for which X-ray CT imaging is desired for the subject P, the imaging purpose, and the imaging region.

  For example, assuming that the medical X-ray CT imaging apparatus is a dental X-ray CT imaging apparatus, the size of the imaging area is a part of the dentition (for example, an area including about 1 to 3 teeth) Setting including the size of the imaging area specifying)), setting including the size of the imaging area specifying the entire dentition, setting designating the size of the imaging area specifying the entire jaw, and the like. The size of the imaging area can be determined, for example, by setting the size of the radius indicating the size of the imaging area, setting the imaging area for the dentition or jaw area shown as a diagram, or the like.

  Here, the imaging area will be described. The configuration of the present application can be suitably applied to a partial region with respect to the entire subject as a living being of an individual. In the entire subject, for example, partial regions such as the head, chest, and abdomen exist. Even in the head, there are more subdivided areas such as a maxillofacial area for dental treatment and an ear nose area for otolaryngology treatment. As described above, there is a partial area in the entire subject individual, and the partial area may have a magnitude relationship.

  The head is a first layer partial area, the jaw area in that is a second layer partial area, the dental arch area in that is a third layer partial area, and the anterior tooth area in that For example, the size of the area may be considered as the depth of the layer in relation to the size of the area, for example, by considering In this case, the wide area layer may be considered as a shallow layer, and the narrow area layer may be considered as a deep layer. The hierarchy may be appropriately provided as the case may be, and the dental arch area may be considered as a first layer partial area, and a partial area in the dental arch such as an anterior tooth area and a molar area may be considered as a second layer partial area .

  In the case of the otolaryngology area, an example in which the area of the ear nose is a first layer partial area and the ear tibial area is a second layer partial area may be considered.

  As described above, partial areas may be set according to the categories of medical care subjects.

  The partial region of the shallow layer does not necessarily have to completely enclose the partial region of the deep layer, and the partial region of the deep layer may have a portion which protrudes over the partial region of the shallow layer.

  In addition, as the imaging purpose, for example, any observation purpose such as root fracture, endodontic treatment, apical lesion, bone regeneration process of implant, periodontal period, wisdom tooth, excess tooth, impacted tooth, salivary stone etc. Is assumed.

  As the imaging site, for example, any of mandibular anterior teeth, mandibular molars, maxillary anterior teeth, maxillary molars, all teeth, temporomandibular joint, face, etc. is assumed.

  The X-ray output condition setting unit 60 automatically sets the output condition of the X-ray generator 22 according to the size of the imaging area received by the imaging information receiving unit 40.

  The X-ray output condition setting unit 60 includes at least one processor. For example, the X-ray output condition setting unit 60 is configured by a computer including at least one processor, a random access memory (RAM), a storage unit, an input / output unit, and the like. The storage unit is configured by a flash memory or a nonvolatile storage device such as a hard disk drive, and stores an X-ray CT imaging condition setting program 60P and the like for setting an X-ray output condition. The RAM is provided as a work area when at least one processor performs a predetermined process. Then, at least one processor performs predetermined arithmetic processing in accordance with the X-ray CT imaging condition setting program 60P or the like stored in the storage unit, and sets the X-ray CT imaging conditions. In setting the X-ray CT imaging conditions, the output conditions of the X-ray generator 22 are automatically set in accordance with the size of the imaging area accepted by the imaging information accepting unit 40.

  Here, the reason for automatically setting the output condition of the X-ray generator 22 according to the size of the imaging area is to adjust the dose to the subject P according to the size of the imaging area. That is, the output condition of the X-ray generator 22 is a condition that affects the dose to the subject P, for example, when performing X-ray CT imaging.

  Here, the dose may be defined from the X-ray output from the X-ray tube which is the X-ray source of the X-ray generator 22. The amount of output can be adjusted by the amount of energy applied to the X-ray tube. For example, if the tube voltage is 40 mA X-ray irradiation and 50 mA X-ray irradiation, the same tube voltage and the same irradiation time, 50 mA has a larger output amount because the applied amount is larger than 40 mA, and the tube voltage is With the same tube current and the same irradiation time for 40 kV X-ray irradiation and 50 kV X-ray irradiation, 50 kV has a larger output amount because the applied amount is larger than 40 kV. The output amount can also be adjusted from the irradiation time. For example, assuming that there are X-ray irradiation for a short time and X-ray irradiation for a long time with the same tube current and tube voltage, the output amount is larger as the irradiation time is longer in the long time. Assuming that the X-ray cone beam shape adjustment unit 127 regulates the irradiation X-rays to be a cone beam shape, temporarily, between the X-ray generator 22 and the X-ray detector 24 for the X-ray cone beam path to be irradiated. If there is nothing to block, the larger the amount of output, the larger the amount of light received on the detection surface of the X-ray detector 24.

  The dose may be the amount of X-rays irradiated to a unit three-dimensional area of a three-dimensional area geometrically formed between the X-ray tube focal point and the X-ray receiving surface. When a cylindrical area having a diameter of 40 mm and a height of 40 mm is to be irradiated with X-rays, the X-ray cone beam shape adjustment unit 127 regulates X-rays to irradiate X-rays only in this area. When light is received by the detection surface of the line detector 24, it is assumed that the light receiving surface has a width of 60 mm and a height of 60 mm. A three-dimensional region of a quadrangular pyramid shape is geometrically formed between the X-ray tube focal point of the X-ray generator 22 and the light receiving surface having a width of 60 mm and a height of 60 mm. When the light receiving surface is further subdivided into, for example, a unit area area of 1 mm in width and 1 mm in height, a very thin quadrangular pyramid 3 between the X-ray tube focal point and the unit area of 1 mm in width and 1 mm in height A dimensional domain is formed. The amount of X-rays irradiated to the unit three-dimensional area may be used as the dose, with the ultra-thin three-dimensional area obtained by dividing the three-dimensional area of the quadrangular pyramid shape as the unit three-dimensional area. Although described later, the unit area may be a pixel unit constituting the detection surface of the X-ray detector 24 (128).

  The dose does not change even if the subject is present in this unit three-dimensional area. When the subject is present, the X-rays irradiated in the unit three-dimensional area are absorbed by the subject and do not reach or are attenuated and reach the detection surface of the X-ray detector 24. On the other hand, when there is no subject, all the X-rays irradiated in the unit three-dimensional area are received by the detection surface of the X-ray detector 24 (the amount absorbed by the air is negligible because it is very small) . In any case, as long as X-ray irradiation is performed under the same conditions, the amount of X-rays irradiated in the unit three-dimensional area is the same as the amount. For example, assuming that X-ray irradiation is performed for each of the large and small output amounts, if the dose is measured for a unit three-dimensional area, the measured dose is larger for the large output X-ray irradiation than for the small output X-ray irradiation. growing.

  In this example, if X-ray irradiation is performed on the same part range of the same subject positioned in the same posture with large and small output amounts respectively, it means that if the output amount of X-ray is large as a result The energy of the X-rays absorbed to the portion of the unit mass of P also increases, and the energy of the X-rays absorbed to the portion of the unit mass of the subject P also decreases if the output amount of X-rays is small.

  When setting the X-ray output conditions, it is not necessary to obtain specific measured values of the dose. For example, if the amount of output from which a good X-ray image can be obtained is obtained as knowledge theoretically, experimentally, and empirically, it is possible to set an appropriate amount of output. It should be possible to assemble by prediction that if a dose is measured, an expected result can be obtained.

  Also, the dose may be considered to be the amount of energy of X-rays absorbed in the unit mass part of the subject P when the subject P is in the irradiation range of X-rays, for example, by absorbed dose It may be represented. When performing X-ray CT imaging, for example, the absorbed dose increases as the tube voltage of the X-ray tube constituting the X-ray generator 22 increases, and the absorbed dose increases as the tube current increases. In addition, if the X-ray irradiation time in performing X-ray CT imaging is increased, the absorbed dose becomes large. Therefore, the output condition of the X-ray generator 22 is, for example, a tube voltage, a tube current, an X-ray irradiation time, etc. when performing X-ray CT imaging. The X-ray irradiation time may be, for example, the speed (rotational speed) at which the X-ray generator 22 and the X-ray detector 24 are turned by the turning drive unit 30, and the X-ray generator 22 and X-rays by the turning drive unit 30. It can be set by the range in which the detector 24 is pivoted (for example, 360 ° or 180 ° or the like). By setting these output conditions appropriately, appropriate dose adjustments can be made. As described above, when the subject P is in the irradiation range of the X-ray, if the output amount of the X-ray from the X-ray tube is increased, the amount of the X-ray absorbed in the unit mass of the subject P as a result is also As this increases, this definition and the previous definition overlap.

  FIG. 2 is a flow chart showing processing by the X-ray output condition setting unit 60.

  That is, when performing X-ray CT imaging, in step T 1, the setting of the imaging region by the operator is accepted through the imaging information accepting unit 40. Acceptance is performed by the input, for example. The setting regarding the imaging region includes the setting regarding at least one of the size of the imaging region, the imaging purpose, and the information regarding the imaging region.

  Thereafter, in the next step T2, the output condition of the X-ray generator is automatically set in accordance with at least one of the size of the imaging region, the imaging purpose, and the information on the imaging region.

  As the size of the imaging area, for example, as shown in FIG. 1, the imaging area E1 and the imaging area E2 wider than the imaging area E1 can be considered.

  In this case, for example, in the case of the relatively narrow (first spread) shooting area E1, the first output condition is set, and in the case of the relatively wide (second spread) shooting area E2, the first output condition is set. 2 Output conditions are set. For example, the dose at the first output condition is the first dose, the dose at the second output condition is the second dose, and the first output condition and the second dose are greater than the second dose. 2 Output conditions are set. In the case of a relatively narrow imaging region E1, X-ray CT imaging is usually performed for the purpose of observing a local part in detail, so X-ray CT imaging is performed under the first output condition where the dose becomes relatively large. Thus, a relatively clear image can be obtained. Also, in the case where the imaging region E2 is relatively large, X-ray CT imaging is generally performed for the purpose of overall observation, so X-ray CT imaging is performed under the second output condition where the dose is relatively small. Thus, low exposure can be achieved.

  In addition, for example, when any of (the observation of) the root fracture, endodontic treatment, apical lesion, or bone regeneration process of the implant is set as the first imaging purpose as the imaging purpose, the first output condition is The second output condition is set in the case where (period), periodontal teeth, superior teeth, excess teeth, impacted teeth, or (observation of) saliva stones are set as the second imaging purpose. For example, the first output condition and the second output condition are set such that the dose at the first output condition is larger than the dose at the second output condition. In order to observe any of root fracture, endodontic treatment, apical lesion, or bone regeneration process of an implant, X-ray CT imaging is usually performed for the purpose of observing the target site in detail. Therefore, relatively clear images can be obtained by performing X-ray CT imaging under the first output condition in which the dose becomes relatively large. In addition, when the purpose is to usually observe any of periodontal teeth, superior teeth, excess teeth, impacted teeth, or saliva, X-ray CT imaging will be performed for the purpose of overall observation, so the dose Low radiation exposure can be achieved by performing X-ray CT imaging under the second output condition that is relatively small.

  When the purpose is detailed observation, such as observation of root fracture, endodontic treatment, apical lesion, or bone regeneration process of implant, this purpose is called detailed observation purpose, and periodontal, wisdom tooth, excess This purpose is usually referred to as the observation purpose if the general situation observation or general situation observation is the purpose, as in the case of the observation of teeth, impacted teeth, or saliva.

  The X-ray CT imaging for achieving the detailed observation purpose is referred to as the detailed observation CT imaging, and the X-ray CT imaging for achieving the normal observation purpose is referred to as the normal observation CT imaging. The operation state in which the detailed observation CT imaging can be performed is called a detailed observation CT imaging mode, and the operation state in which the normal observation CT imaging can be performed is called a normal observation CT imaging mode.

  When imaging the same region in the X-ray CT imaging region of the same size, it is also conceivable to change the output condition according to the imaging purpose. For example, when performing X-ray CT imaging for the purpose of the first imaging for the purpose of diagnosing the root fracture for the same area (the size is also the same) including the lower anterior teeth, the first output condition is set to When performing X-ray CT imaging for the purpose of the second imaging purpose, it is conceivable to set the second output condition. In this way, it is possible to reduce the exposure dose to the lower front teeth region at the time of observation of the stone. In addition, when diagnosing root fracture, it is possible to obtain an image that is relatively sharp and suitable for detailed observation.

  In addition, for example, when any of mandibular anterior teeth, mandibular molars, maxillary anterior teeth, and maxillary molars is set as the first imaging site as the imaging site, the first output condition is set, and all teeth and all teeth from the jaws are set. When any of the wide region extending to the joint and the face is set as the second imaging region, the second output condition is set. In the case of this example, since the first imaging region and the second imaging region are wide and narrow in the area, there is also a relationship between the imaging area of the first spread and the imaging area of the second spread. Then, for example, the first output condition and the second output condition are set such that the dose in the first output condition is larger than the dose in the second output condition. When the target is any of the lower incisors, lower molars, upper incisors, and upper molars, X-ray CT imaging is usually performed for the purpose of observing the relatively narrow imaging site in detail. A relatively clear image can be obtained by performing X-ray CT imaging under the first output condition in which the dose is relatively large. In addition, in the case of using all teeth, a wide area extending from all teeth to the temporomandibular joint, or the face as the imaging region, the X-ray CT imaging is performed for the purpose of overall observation, so the dose is relatively small. Low radiation exposure can be achieved by performing X-ray CT imaging under the second output condition.

  Further, it is also conceivable to change the output condition when imaging different regions in the CT imaging region of the same size. For example, an area including the temporomandibular joint in which the X-ray cone beam path exists (the first imaging site) and an area including the lower front teeth (second imaging area) in which the X-ray cone beam path deviates from the X-ray cone beam path In contrast, suppose that CT imaging regions of the same size are set. In this case, the shooting purpose may or may not be set. When the shooting purpose is set, the same purpose may be used. Then, the irradiation conditions for the former, ie, the temporomandibular joint area, and the irradiation conditions for the latter, ie, the mandibular anterior teeth area, are set, the first output condition for the temporomandibular joint area, and the second output condition for the mandibular anterior teeth area Thus, the dose to the lower anterior region can be reduced. In addition, with regard to the temporomandibular joint in which the base of the skull is in the path of the X-ray cone beam, clear images can be obtained regardless of the presence of the base of the skull.

  In the case of imaging different regions in the same size CT imaging region, another classification may be performed. For example, assuming that a cylindrical area having a diameter of 40 mm and a height of 40 mm is to be an X-ray CT imaging target, the molar area is classified into a molar area and an anterior area based on the amount of hard tissue. Apply the second power condition with the anterior region as the region with less hard tissue, and apply the first power condition and the second power condition so that the dose at the first power condition is larger than the dose at the second power condition. The output conditions may be set.

  Also, even in the same anterior region, there is a difference that the anterior region in the upper jaw has more hard tissue around the upper anterior region and the lower anterior region in the lower jaw has less hard tissue around the upper teeth in the upper jaw and the lower teeth in the lower jaw. Even in the same molar region, in the upper molar region of the upper jaw and the lower molar region of the lower jaw, there is a difference that the surrounding hard tissue is more in the upper molar region of the upper jaw and the surrounding hard tissue is lower in the lower molar region of the lower jaw.

  Focusing on this, for example, the upper molar region of the upper jaw is classified into a first set, the lower molar region of the lower jaw and the anterior tooth region of the upper jaw are classified into a second set, and the anterior tooth region of the lower jaw is a third set Classified into

  In the relationship between the first set and the second set, the first set is a first imaging region, the second set is a second imaging region, and a dose based on a first output condition according to the first imaging region is The first output condition and the second output condition are defined to be larger than the dose based on the second output condition according to the second imaging region.

  In the relationship between the second set and the third set, the second set is the first imaging region, the third set is the second imaging region, and the dose based on the first output condition according to the first imaging region is The first output condition and the second output condition are defined to be larger than the dose based on the second output condition according to the second imaging region.

  The setting example of FIG. 20 described later is such a setting example.

  In addition to setting by the amount of hard tissue, setting may be performed by the level of hard tissue density.

  In the above example, the output condition is set based on one of the size of the imaging area, the imaging purpose, and the information on the imaging site. However, the size of the imaging area, the imaging purpose and the imaging site The output conditions may be set based on the two combinations, or based on the combination of the size of the imaging region, the imaging purpose, and the imaging region.

  When the output condition of the X-ray generator according to at least one of the size of the imaging region, the imaging purpose, and the information on the imaging region is automatically set, the setting process on the X-ray output condition is completed.

  The X-ray CT imaging apparatus 10 irradiates the X-ray cone beam from the X-ray generator 22 according to the set output condition of the X-ray generator, and X-ray detector 24 transmits the X-ray cone beam transmitted through the object P. The X-ray generator 22 and the X-ray detector 24 are turned around the subject P by the turning drive unit 30 while performing detection, and X-ray CT imaging is performed.

  Then, based on the data detected by the X-ray detector 24, an X-ray CT image is generated.

  According to the X-ray CT imaging apparatus 10 configured as described above, the medical X-ray CT imaging condition setting method, and the X-ray CT imaging condition setting program 60P, according to at least one of the received information on the imaging purpose and the imaging region By setting the output conditions of the X-ray generator 22 automatically, exposure can be reduced as much as possible. Also, usually, the sizes of the imaging areas E1 and E2 and the imaging site are set according to the imaging purpose, X is selected according to at least one of the size of the imaging area, the imaging purpose and the imaging site. By automatically setting the output conditions of the line generator 22, it is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose.

  For example, in the case of a relatively small imaging region E1, a relatively clear X-ray CT image can be obtained by performing X-ray CT imaging under the first output condition in which the dose becomes relatively large. In the case of X-ray CT imaging for a relatively narrow imaging range E1 targeting a part of teeth of a dental arch, an X-ray CT for the purpose of treating a part of teeth of the dental arch, etc. A picture is taken. Therefore, by obtaining a relatively clear X-ray CT image, a clear image suitable for treatment can be obtained. Also, for example, in the case of a relatively large imaging region E2, performing X-ray CT imaging under a second output condition such that the dose is relatively small enables performing X-ray CT imaging under low exposure conditions it can. In the case of X-ray CT imaging for a relatively large imaging area E2 which normally covers the entire dental arch, the entire jaw area, etc., X-ray CT imaging for the purpose of observing the entire shape of teeth and skeleton is necessary. To be done. Therefore, an X-ray CT image suitable for such an overall observation can be obtained under low exposure X-ray CT imaging conditions.

  In addition, for example, when root fracture, endodontic treatment, apical lesion, bone regeneration process of an implant, etc. are set as imaging purposes, X-ray CT imaging is performed under the first output condition in which the dose becomes relatively large. By doing this, a relatively clear image can be obtained. Also, usually, when any of periodontal teeth, superior teeth, excess teeth, impacted teeth, or saliva stones are set, low radiation exposure is performed by performing X-ray CT imaging under the second output condition with a relatively small dose. Can be

  Also, for example, when any of the lower anterior teeth, lower molars, upper anterior teeth, and upper molars which are a part of the dental arch is set as the imaging region, X is generated under the first output condition in which the dose becomes relatively large. By performing line CT imaging, a relatively clear image can be obtained. In addition, when any one of the full teeth, the temporomandibular joint, and the face wider than the size including the entire dental arch is set as the imaging region, X-ray CT imaging is performed under the second output condition where the dose is relatively small. Low exposure can be achieved.

Second Embodiment
An X-ray CT imaging apparatus according to a second embodiment will be described.

<About the whole composition>
FIG. 3 is an overall view showing the configuration of the X-ray CT imaging apparatus 110 according to the second embodiment, and FIG. 4 is a perspective view when the X-ray CT imaging apparatus 110 according to the second embodiment is viewed obliquely from above. It is. In each of the drawings, for convenience of explanation, an XYZ coordinate system may be set in the entire space in which the X-ray CT imaging apparatus 110 exists. In the present XYZ coordinate system, with reference to the head P supported by the X-ray CT imaging apparatus 110, the right direction is X (+) direction, the left direction is X (-) direction, and the front is Y (+) direction, The rear is taken as a Y (-) direction, the upper as a Z (+) direction, and the lower as a Z (-) direction.

  The X-ray CT imaging apparatus 110 includes an imaging unit 120 and an image processing apparatus 180. The imaging unit 120 is a device that collects X-ray projection data by performing X-ray imaging on the subject P. The imaging unit 120 is housed in, for example, the X-ray prevention chamber 146 and used. The image processing apparatus 180 processes the X-ray projection data acquired by the imaging unit 120 to generate various X-ray images (specifically, a panoramic image, a CT image, a cephalo image, etc.).

  However, the imaging unit 120 may perform X-ray CT imaging of the subject P, and the image processing apparatus 180 processes the X-ray projection data acquired by the imaging unit 120 to generate an X-ray CT image. As long as it is In the following, the configuration in which the X-ray CT imaging apparatus 110 performs CT imaging will be mainly described.

  The imaging unit 120 includes an X-ray generator 126, an X-ray detector 128, a swing support unit 124, and a main body control unit 150 (see FIGS. 5 and 6 described later, not shown in FIG. 3).

  The X-ray generator 126 includes an X-ray tube which is an X-ray source that generates X-rays. An X-ray cone beam is emitted from the X-ray generator 126. The intensity (output intensity) of the x-ray cone beam is controlled by changing at least one of the tube voltage and the tube current supplied to the x-ray generator 126. Control of the X-ray generator 126 (specifically, control of at least one of the tube voltage and the tube current) is performed by the X-ray generator drive controller 152 h of the main body controller 150.

  An X-ray cone beam shape adjusting unit 127 is provided on the side of the X-ray generator 126 where the X-ray cone beam is irradiated. The X-ray generator 126 and the X-ray cone beam shape adjustment unit 127 are supported at one end of the pivot support 124.

  The X-ray cone beam shape adjustment unit 127 regulates the spread of the X-ray cone beam emitted from the X-ray generator 126, and adjusts the X-ray cone beam to a shape according to the imaging purpose. The X-ray cone beam shape adjusting unit 127 is, for example, a member in which an X-ray regulation hole is formed, and one of X-rays generated from the X-ray generator 126 according to the shape and size of the X-ray regulation hole. Allow passage of parts and shield outside of the passage range. This limits the range of the x-ray beam going to the x-ray detector 128. For example, the X-ray cone beam shape adjusting unit 127 is provided with a plurality of types of X-ray regulation holes and switches X-ray regulation holes for regulating X-rays, or moves members forming the X-ray regulation holes. By adjusting the opening width of the X-ray regulating hole or the like, the amount of X-rays generated from the X-ray generator 126 to be shielded, that is, the regulating amount is adjusted. The X-ray cone beam shape adjustment unit 127 is controlled by the X-ray generator drive control unit 152 h.

  The X-ray detector 128 detects an X-ray cone beam emitted from the X-ray generator 126. The X-ray detector 128 may be configured by a flat panel detector (FPD) or an X-ray fluorescence intensifier (I.I .: Image Intensifier) or the like having a flat detection surface.

  The plurality of detection elements disposed on the detection surface of the X-ray detector 128 convert the intensity of the incident X-ray into an electrical signal. Then, the electrical signal is input as an output signal to the main control unit 150 or the image processing apparatus 180, and an X-ray projection image is generated based on the signal.

  The X-ray detector 128 is supported at the other end of the pivot support 124 so as to face the X-ray generator 126 at a distance. The X-ray cone beam emitted from the X-ray generator 126 is irradiated to the detection surface of the X-ray detector 128.

  The swing support portion 124 is supported by the horizontal arm 123 in a suspended manner via the rotation shaft portion 125. The pivoting support portion 124 extends in the horizontal direction while being supported in a suspended manner. A housing 124 a is attached to one end of the turning support 124, and a housing 124 b is attached to the other end of the turning support 124. The X-ray generator 126 and the X-ray cone beam shape adjustment unit 127 are supported in the housing 124 a in a state of being accommodated. The X-ray generator 126 irradiates an X-ray cone beam from one end to the other end of the pivot support 124. In the housing 124b, the X-ray detector 128 is accommodated in a posture in which the X-ray detection surface faces the X-ray generator 126 side. Thus, the pivot support 124 supports the X-ray generator 126 at one end and the X-ray detector 128 at the other end.

  The pivot support portion 124 is supported via a support 121 and a horizontal arm 123.

  The columns 121 are vertically supported on a base 121B placed on a floor surface or the like. A lift unit 122 is provided on the support column 121 so as to be capable of moving up and down. The elevation unit 122 is driven to move up and down by an elevation drive mechanism. A moving mechanism including a ball screw mechanism, a motor and the like, and a linear actuator such as a linear motor are used as the raising and lowering drive mechanism, and are incorporated in the support column 121 to raise and lower the raising and lowering unit 122. A horizontal arm 123 is supported by the elevation unit 122 so as to extend in the horizontal direction. The pivot drive mechanism 130 is incorporated into the tip of the horizontal arm 123.

  The pivot drive mechanism 130 is a mechanism for pivoting the pivot support portion 124. In the present embodiment, the turning drive mechanism includes a turning shaft moving mechanism 134 and a turning mechanism 132 movably supported by the turning shaft moving mechanism 134.

  The pivot shaft moving mechanism 134 is a mechanism for moving the rotary shaft portion 125 together with the pivot mechanism 132 in a direction (here, the horizontal direction) intersecting the pivot axis X1 of the rotary shaft portion 125. As the pivot axis moving mechanism 134, for example, an XY table mechanism in which two linear actuators are combined in directions orthogonal to each other can be employed. Then, the rotary shaft moving mechanism 134 moves the rotary shaft 125 along with the rotary mechanism 132 in the horizontal direction, so that the rotary shaft 125 can be disposed at a desired position, and the X-ray generator 126 and X The pivot axis of the line detector 128 can be set to any position.

  The pivoting mechanism 132 is provided with a pivot drive actuator, specifically a motor 132a, as a pivot drive unit, and is supported movably in the horizontal direction by the pivot shaft moving mechanism 134. An upper end portion of the rotation shaft portion 125 protruding upward from the extension direction middle portion of the turning support portion 124 is rotatably supported by the turning mechanism 132. The rotational support of the motor provided in the pivoting mechanism 132 is transmitted to the rotating shaft 125, whereby the pivot support 124 and the X-ray generator 126 and the X-ray detector 128 supported by the pivot support 124 are pivoted. Do. The rotational movement of the motor provided in the turning mechanism 132 is transmitted to the rotating shaft 125 via a transmission mechanism such as a gear or a pulley, as required.

  In the present embodiment, the X-ray generator 126 and the X-ray detector 128 are attached to both ends of the U-shaped pivot support 124, but the X-ray generator and the X-ray detector are It may be supported by the annular member in the opposite state. Such an annular member can be pivotably supported by providing a shaft portion on a support member that traverses a portion of the circumferential direction or the inside of the annular member. Further, in the present embodiment, the X-ray generator 126 and the X-ray detector 128 are rotatably supported around the vertical axis, but are rotatably supported around an axis or the like in the oblique direction with respect to the vertical direction. It may be done.

  The pivot support portion 124 can be raised and lowered by the lift portion 122 in accordance with the height of the head P. Also, the pivot drive mechanism 130 can pivot the pivot support 124 such that the X-ray generator 126 and the X-ray detector 128 pivot around the head P.

  In addition, a lifting and lowering unit 141A for head fixing device is provided on the support column 121 so as to be capable of lifting and lowering. The head fixing device lifting unit 141A is provided below the lifting unit 122. The head fixing device arm 141 is provided so as to extend in the same direction as the horizontal arm 123 from the head fixing device lifting section 141A. The head fixing arm 141 extends through the lower side of the horizontal arm 123 to a lower position between the X-ray generator 126 and the X-ray detector 128. A head fixing device 142 is provided at the tip of the head fixing device arm 141. The head fixation device 142 is located between the x-ray generator 126 and the x-ray detector 128. The head fixing device 142 includes a chin rest 142a capable of mounting and supporting a jaw of a head P as a subject, and a holding portion 142b holding the head P as a subject from both outer sides thereof. The jaws of the head P are supported on the chin rest 142a, and the head P is sandwiched by the holding portion 142b, whereby the head P is located between the X-ray generator 126 and the X-ray detector 128. It is held in place. The head fixing device 142 may be configured by at least one of the chin rest 142a and the holding portion 142b.

  In addition, a head for cephalography head fixing device drooping arm 143 is provided so as to extend in the horizontal direction on the opposite side to the side where the horizontal arm 123 extends from the support column 121, and this cephalography head fixing device drooping arm 143 And a head fixing device 144 for cephalography is supported in a suspended state. The head fixing device 144 for cephalography incorporates an X-ray detector 128 b for cephalography. Cephalography head fixing device drooping arm 143, Cepharography head fixing device 144, Cepharographic X-ray detector 128b, and a mechanism including other peripheral components as needed are cephalography X-rays Configure the detection mechanism. A mechanism including the horizontal arm 123, the pivot support 124, the casing 124a, the X-ray generator 126, and other peripheral components as required during cephalography, constitutes a cephalography X-ray generation mechanism. The cephalography X-ray detection mechanism and the cephalography X-ray generation mechanism constitute an imaging mechanism for cephalography.

  In the present embodiment, each part for cephalography, for example, the cephalography head fixing device drooping arm 143, the cephalography head fixing device 144, the cephalography X-ray detector 128b, etc. may be omitted. Good.

  A main body control unit 150 including an operation panel device 158 is provided at an intermediate portion in the extension direction of the head fixing device arm 141.

  When performing X-ray imaging, while the head P as the subject is fixed by the head fixing device 142, the X-ray is performed in a state in which the turning support unit 124 is stopped or rotated according to the desired imaging mode. Take a picture. In particular, the X-ray generator 126 and the X-ray detector 128 are pivoted around the subject P by rotating the pivot support 124 to obtain X-ray image data necessary for generating an X-ray CT image or the like. be able to. In addition, by performing X-ray imaging in a state in which the swing support portion 124 is rotated within a predetermined range, a panoramic captured image can be obtained. The X-ray CT imaging apparatus 110 can also perform X-ray imaging for obtaining a cephalometrically-captured image and a pseudo intraoral radiography-captured image. For example, the head P is fixed to the head fixing device 144 for cephalography supported by the head 143 for cephalography head fixing device drooping arm extending horizontally from the support column 121 in a state where the turning support 124 is stopped. By performing X-ray irradiation from the X-ray detector 128 and performing X-ray imaging, a cephalometrically-captured image can be obtained.

  The main body control unit 150 is configured by a computer or the like, configured to be able to receive each instruction to the imaging unit 120, and configured to be able to control each operation of the imaging unit 120. The main body control unit 150 is fixed to a head fixing device arm 141 extending in the horizontal direction from the support column 121. The main body control unit 150 is provided with an operation panel device 158 for displaying various information from the main body control unit 150 and receiving various instructions for the main body control unit 150. Here, the operation panel device 158 is a touch panel including a display device such as a liquid crystal display panel and a touch detection unit disposed on the display screen of the display device. An operation on the X-ray CT imaging apparatus 110 can be received by detecting the touch operation of the user on the display screen by the touch detection unit. A push button or the like may be provided near the operation panel device 158 or the like. In addition, the display device and the input device for receiving the user's operation may be provided separately.

  A push button switch called a dead man switch connected to the main body control unit 150 is provided on the outside of the wall of the X-ray chamber 146 that accommodates the imaging unit 120. X-ray irradiation is performed only while the operator presses the dead man switch.

  The image processing apparatus 180 includes an information processing main unit 182 configured of, for example, a computer, a work station, etc., and is connected so as to be able to transmit and receive various data to and from the imaging unit 120 by a communication cable. However, transmission and reception of data may be performed between the imaging unit 120 and the image processing apparatus 180 by wireless communication. The information processing main body unit 182 can execute various image processing and the like based on the data transmitted from the imaging unit 120.

  The image processing apparatus 180 is connected to a display unit 184a configured by a display device such as a liquid crystal monitor, and an operation unit 184b configured by a keyboard, a mouse, and the like. The operator can give various instructions to the information processing main unit 182 by pointer operation or the like via a mouse or the like on characters and images displayed on the display unit 184a. The display unit 184a may be configured by a touch panel.

  Part or all of the processing of the image processing apparatus 180 may be executed by the main control unit 150. Alternatively, part or all of the processing of the body control unit 150 may be performed by the image processing apparatus 180. That is, each process of main body control unit 150 and image processing apparatus 180 may be executed by a single computer provided at any place, or distributed by a plurality of processors provided at any place. It may be processed.

<About the block diagram of the X-ray CT imaging apparatus>
FIG. 5 is a functional block diagram of the X-ray CT imaging apparatus 110, and FIG. 6 is a block diagram showing an electrical configuration of the main body control unit 150. As shown in FIG.

  The main body control unit 150 controls an X-ray imaging operation of the imaging unit 120, and a central processing unit (CPU) 150a, a random access memory (RAM) 150b, a storage unit 150c, and an input / output unit 150d as an example of a processor. The operation input unit 150e, the image output unit 150f, and the like are configured by computers interconnected via a bus line 150g (see FIG. 6). The storage unit 150c is configured by a flash memory or a non-volatile storage device such as a hard disk drive, receives various instructions regarding X-ray imaging through the operation panel device 158 or the like, and the imaging unit 120 An imaging program 151 or the like for controlling the operation at the time of performing the line CT imaging is stored. The X-ray CT imaging condition setting program 151a automatically sets the output conditions of the X-ray generator 126 according to the settings related to X-ray imaging when the imaging program 151 receives settings related to X-ray imaging through the operation panel device 158 and the like. It is included.

  Further, the storage unit 150 c stores a reference table 152 in which the output condition of the X-ray generator 126 is associated with the setting regarding the X-ray imaging. An example of the reference table 152 will be described later.

  The RAM 150 b is provided as a work area when the CPU 150 a performs a predetermined process. The input / output unit 150 d is connected to the X-ray generator 126, the X-ray detector 128, etc., such as a motor included in the turning drive mechanism 130 of the imaging unit 120. The operation input unit 150 e is connected to the touch detection unit of the operation panel device 158, and the image output unit 150 f is connected to the display unit of the operation panel device 158.

  In the main control unit 150, the CPU 150a performs arithmetic processing according to the procedure described in the photographing program 151 and the instruction received through the operation panel device 158 etc., thereby controlling the display on the operation panel device 158, and relates to photographing. Accept the settings. Further, the CPU 150a performs arithmetic processing in accordance with the procedure described in the imaging program 151 and the received instructions for imaging, thereby driving and controlling the swing drive mechanism 130, the X-ray generator 126, the X-ray detector 128, and the like. . Thereby, the X-ray generator 126 and the X-ray detector 128 turn around the subject P, and the X-ray cone beam irradiated from the X-ray generator 126 passes through the subject P and enters the X-ray detector 128 Do. Then, based on the data detected by the X-ray detector 128, an X-ray CT image can be generated.

  As shown in FIG. 5, the main body control unit 150 includes a support drive control unit 152a, a mode setting reception unit 152b, an imaging information reception unit 152c, an X-ray output condition setting unit 152d, an output condition setting reception unit 152e, and X-ray imaging. A data processing unit 152f, an X-ray detection unit drive control unit 152g, an X-ray generator drive control unit 152h, and an image quality setting unit 152i are provided. Each of these control units is a function realized by the CPU (general-purpose circuit) operating according to the photographing program 151. Note that part or all of these functions may be realized as hardware by configuring them with a dedicated circuit or the like. Also, each of the above functions may be distributed and processed by a plurality of computers. The mechanical entities of the functions implemented by the CPU operating according to the program are the electrical signals as the program and the circuit that functions by the program.

  The support drive control unit 152 a controls the swing drive mechanism 130 to control the swing of the swing support unit 124. Specifically, the support drive control unit 152 a rotates the X-ray generator 126 and the X-ray detector 128 supported by the pivot support 124 around the rotation axis X when performing X-ray CT imaging. Thus, the X-ray generator 126 and the X-ray detector 128 are pivoted around the subject P. The support drive control unit 152a can control the speed at which the X-ray generator 126 and the X-ray detector 128 turn and the turning range (turning angle) in accordance with the output conditions set by the X-ray output condition setting unit 152d described later. It may be

  The mode setting receiving unit 152 b receives the setting of the low dose mode and the high resolution mode through the operation panel device 158. The low dose mode is a mode for performing X-ray CT imaging with low dose depending on the size of the imaging region, the imaging purpose, and the imaging region, as described later. That is, as described later, the present X-ray CT imaging apparatus 110 can execute low-dose X-ray CT imaging and high-resolution X-ray CT imaging. The low dose X-ray CT imaging is an imaging in which the X-ray CT imaging is performed in a state in which the X-ray dose emitted from the X-ray generator 126 is suppressed. Become. The high resolution mode is a mode for performing high resolution X-ray CT imaging. High-resolution X-ray CT imaging is imaging that performs X-ray CT imaging at a higher dose than in the case of low-dose X-ray CT imaging, and while the dose to the object P increases, the X-ray CT with less noise and clear You can get an image. The output condition of the X-ray detector 128 is set according to each of the low dose mode and the high resolution mode. This setting is defined, for example, in the reference table 152. This point will be described later.

  The low resolution mode is a specific example of the normal observation CT imaging mode, and the high resolution mode is a specific example of the detailed observation CT imaging mode.

  In the X-ray CT imaging apparatus 110, it is not essential to switch between the low dose mode and the high resolution mode. For example, the configuration may be such that only the low dose mode can be performed.

  The imaging information reception unit 152 c receives imaging information regarding at least one of the size of the imaging area, the imaging purpose, and the imaging region through the operation panel device 158. The imaging information has settings regarding at least one of the size of the imaging area, the imaging purpose, and the imaging region. Acceptance is performed by the input, for example. In the present embodiment, an example will be described in which the imaging information reception unit 152c receives the size of the imaging region and the imaging region through the operation panel device 158. An example in which the shooting information receiving unit 152c receives a shooting purpose will be described in a modification below.

  Here, the photographing information accepting unit 152c also accepts setting of the physical constitution through the operation panel device 158. More specifically, as the setting of the physical constitution, the imaging information reception unit 152c receives the setting of whether the subject is a physical constitution of a child or a physical constitution exceeding a child.

  The X-ray output condition setting unit 152d sets an X-ray output condition according to at least one of the size of the imaging region, the imaging purpose, and the imaging region received by the imaging information receiving unit 152c. In the present embodiment, an example will be described in which the imaging information reception unit 152c sets an X-ray output condition according to the size of the imaging region. An example in which the X-ray output condition setting unit 152d sets the X-ray output condition in accordance with the imaging purpose, the imaging region, and the like will be described in a later modification.

  Here, the X-ray output condition setting unit 152 d sets the size of the imaging area received by the imaging information reception unit, the imaging purpose regarding the imaging purpose and the imaging area regarding at least one of the imaging regions, and Depending on the setting, more specifically, the output condition of the X-ray generator 126 is automatically set according to the setting of whether the subject is a physical size of a child or a physical size exceeding that of a child. When the output condition setting acceptance unit 152 e described below sets the output condition manually, the output condition setting acceptance unit 152 e changes the automatically set output condition according to the content of the manual setting.

  The output condition setting acceptance unit 152 e accepts manual setting by the operator for the output condition of the X-ray generator 126 through the operation panel device 158. That is, when the operator wants to change and adjust the output condition arbitrarily with respect to the output condition automatically set by the X-ray output condition setting unit 152 d, the operator changes the output condition automatically set through the operation panel device 158. You can enter the adjustment.

  The manual setting function for automatically set output conditions may be omitted.

  The X-ray imaging data processing unit 152 f performs image processing such as noise reduction processing on the data detected by the X-ray detector 128. As the noise reduction processing, it is possible to adopt a median filter in which the value of each pixel is a median of peripheral pixels, a moving average filter in which the value of each pixel is an average of peripheral pixels, or the like.

  The X-ray detection unit drive control unit 152 g controls the drive of the X-ray detector 128. The X-ray detection unit drive control unit 152g may be capable of controlling on / off of a binning function of processing a plurality of pixels of the X-ray detector 128 together as one pixel, a unit of pixels to be collected by the binning function, and the like.

  The X-ray generator drive control unit 152h controls at least one of the tube voltage and the tube voltage of the X-ray generator 126 in accordance with the X-ray output condition automatically set by the X-ray output condition setting unit 152d. It performs on / off control of the line generator 126 and the like.

  The image quality setting unit 152i performs X-ray CT according to at least one of the setting of the imaging area received by the imaging information reception unit 152c and the output condition of the X-ray generator 126 automatically set by the X-ray output condition setting unit 152d. Automatically set the image quality of the image. Here, the image quality setting unit 152i automatically sets the image quality of the X-ray CT image by adjusting the voxel size when reconstructing the X-ray CT image based on the image obtained by the X-ray detector 128. For example, in an output condition, there is a relationship in which there is a first dose and a second dose, and the first dose is larger than the second dose, and setting the first dose is the first output condition If it is the second output condition that sets the second dose, noise is likely to get on when the second output condition is automatically set, so that the effect of the noise is eliminated as much as possible. Set the size relatively large. Also, for example, when the first output condition is automatically set, it is difficult for noise to get on, so the voxel size is made smaller than in the above case, and a clear image with high resolution is obtained. Further, for example, when a relatively wide imaging region E2 is photographed under the second output condition as compared with a relatively narrow photographing region E1, the voxel size may be set relatively large.

  The image quality setting unit 152i may automatically set the image quality of the X-ray CT image according to the received setting information of the imaging area regardless of the set output condition of the X-ray generator 126. For example, it is possible to reduce the voxel size when receiving the detailed observation purpose described above, and to increase the voxel size when receiving the normal observation purpose described above. The voxel size may be reduced when receiving a relatively narrow first spread imaging area, and the voxel size may be increased when receiving a relatively wide second spread imaging area. .

  The setting value (for example, voxel value) in the image quality setting unit 152i is given to the image processing device 180. The image processing device 180 reconstructs an X-ray CT image based on the set voxel value. That is, three-dimensional data is generated based on the data detected by the X-ray detector 128, and an X-ray CT image is generated by cutting out a tomographic image from the three-dimensional data. The voxel value is a three-dimensional unit when generating the three-dimensional data.

  The setting example of the image quality by the image quality setting unit 152i is not limited to the above example. The role of the image quality setting unit 152i is to eliminate the influence of the noise as much as possible because the noise easily gets on when the output condition with a relatively small dose is automatically set. Conversely, when an output condition with a relatively large dose is automatically set, it is possible to obtain data with relatively clear boundaries by itself and less noise, so noise can be reduced. Although the image quality adjustment is unnecessary, it is preferable that the degree of the image quality adjustment be smaller.

  Such image quality setting processing by the image quality setting unit 152i may be employed other than adjusting the voxel size as described above.

  For example, the image quality setting unit 152i may adjust the unit of pixels to be combined by turning on or off the binning function of the X-ray detector 128 or by using the binning function. For example, when an output condition with a relatively small dose is automatically set, the binning function may be turned on, and when an output condition with a relatively large dose is automatically set, the binning function may be turned off. Also, for example, when an output condition having a relatively small dose is automatically set, a pixel unit to be summarized by the binning function is more than a pixel unit to be summarized by the binning function when an output condition having a relatively large dose is automatically set. You may enlarge it. Turning on the binning function while turning it off or increasing the pixel unit to be combined by the binning function is referred to as high-binning.

  The image quality setting unit 152i may adjust the detection sensitivity of the X-ray detector 128 to set the image quality. For example, when an output condition with a relatively small dose is automatically set, the sensitivity may be increased, and when an output condition with a relatively large dose is automatically set, the detection sensitivity may be reduced. As a specific example, capacitor elements (capacitors) for receiving pixel signals on the detection surface are prepared in a plurality of types or variably in capacity, configured to be switchable or changeable, and an output condition having a relatively small dose When the automatic setting is performed, the capacity is reduced, and when the output condition with a relatively large dose is automatically set, the capacity is increased. Each of the signal strength evaluations in the capacitors is configured to be performed in multiple stages (the same number of stages common to each capacitor, for example, 16 bits are acceptable).

  Also, the image quality setting unit 152i may adjust the slice thickness when reconstructing an X-ray CT image. That is, three-dimensional data is generated based on the data detected by the X-ray detector 128, and a slice is cut out from this three-dimensional data, and one slice or a plurality of slices are superimposed to form an X-ray CT. Generate an image. Increasing the thickness of the slice contributes to noise reduction, which leads to the averaging of the values in the thickness direction. Therefore, if an output condition with a relatively small dose is automatically set, the slice thickness is set large. If an output condition with a relatively large dose is automatically set, the slice thickness is set small. It is also good. The automatic setting value of the slice thickness is given to the image processing device 180. The image processing apparatus 180 reconstructs an X-ray CT image based on the set slice thickness.

  Also, noise reduction processing such as median filter, smoothing filter such as moving average filter, etc. on at least one of the data obtained by the X-ray detector 128, the three-dimensional image based on the data, and the X-ray CT image Or not may be adjusted. For example, noise reduction processing is performed when an output condition with a relatively small dose is automatically set, and noise reduction processing is not performed when an output condition with a relatively large dose is automatically set. Good. Between the two, the strength of the noise processing may be changed. Whether to execute noise processing or a selection command is given from the main control unit 150 to the image processing apparatus 180.

  Further, when the main control unit 150 executes each of the above processes, particularly when executing the processing as the mode setting reception unit 152 b, the X-ray output condition setting unit 152 d, and the output condition setting reception unit 152 e, While controlling the display content in 158, the touch operation with respect to the operating panel apparatus 158 is received. In this respect, the operation panel device 158 outputs a mode setting operation unit 158a for performing setting operation on the mode setting reception unit 152b, a photographing information setting operation unit 158b for performing setting operation on the X-ray output condition setting unit 152d, It can function as an output condition setting operation unit 158 c for performing a setting operation on the condition setting reception unit 152 e.

  Here, the above-mentioned processing to increase the voxel size, noise reduction processing by a filter or the like, binning processing, processing to increase the slice thickness, and the like are processing in the direction to combine the signal of a certain pixel and the signal of nearby pixels. It is called pixel signal coupled processing.

  Among them, signal processing on the X-ray detector side is referred to as pixel signal combination type detection signal processing such as binning switching of the X-ray detector 128, and an image on the image processing device side such as processing to increase slice thickness. The processing is referred to as pixel signal combination type image processing.

  The following control can be considered as an example of control. The first imaging area and the second imaging area can be considered as imaging target areas. When the areas are compared, the first imaging area is narrow and the second imaging area is wide. The first imaging area is X-ray CT imaging under the first output condition and the second imaging area is under the second output condition. The first output condition and the second output condition are set by the X-ray output condition setting unit 152d, the dose in the first output condition is a first dose, and the dose in the second output condition is a second dose. When the sizes are compared, the first dose is large and the second dose is small.

  The first projection image data is obtained by the X-ray CT imaging of the first imaging region, and the second projection image data is obtained by the X-ray CT imaging of the second imaging region.

  The image quality setting unit 152i sets the image quality of the generated X-ray CT image. For example, in the X-ray CT imaging of the second imaging region, high-binning is performed, or the pixel signal combining type processing is performed on the second projection image data.

  The main body control unit 150 is communicably connected to the image processing apparatus 180 via a communication I / F (interface) 154.

  The image processing apparatus 180 is configured by a computer, a work station or the like. That is, the image processing apparatus 180 includes a CPU as an example of a processor that performs various types of arithmetic processing, a ROM that is a read only memory that stores a basic program, and a RAM that is a readable and writable memory that stores various information. The CPU functions as the control unit 181 by operating according to the control program. The control unit 181 is connected to the image processing unit 181 a and the storage unit 183. The image processing unit 181a processes an X-ray transmission image generated based on a signal output from the X-ray detector 128 when the imaging unit 120 performs X-ray CT imaging, and generates an X-ray CT image. . The storage unit 183 stores an application or data.

  The image processing unit 181a is a function realized by the image processing processor. The image processing unit 181a may be a function realized by the CPU of the control unit 181 operating according to an application program.

  For example, when X-ray CT imaging is performed by the imaging unit 120, the image processing unit 181a performs predetermined preprocessing, filter processing, back projection processing, and the like on a plurality of acquired projection images. A two-dimensional image is generated, and a CT image of each tomographic obtained by slicing the imaging region is generated based on the three-dimensional image. For example, a plurality of projection images obtained by X-ray CT imaging are processed as frame data, three-dimensional mesh data composed of three-dimensional voxel data (three-dimensional pixels in image processing) is constructed, and three-dimensional mesh data The slice data cut out is visualized into a tomographic image, or visualized into a volume rendering image obtained by processing 3D mesh data. Thus, an X-ray CT image is generated.

  The control unit 181 is connected to a display unit 184 a for displaying an image indicating various information, and an operation unit 184 b for the operator to perform an operation input. The image processing apparatus 180 is connected to the main control unit 150 so as to be able to communicate information via the communication I / F 185.

<Various setting examples>
An example in which the main control unit 150 receives various settings via the operation panel device 158 will be described.

  FIG. 7 is a view showing a display example of the operation panel device 158. As shown in FIG.

  As shown in the figure, on the operation panel device 158, imaging mode selection images 201, 202, and 203 corresponding to a plurality of X-ray imaging modes are displayed. Here, the photographing mode selection images 201, 202, 203 and 204 are displayed in the upper part of the display area of the operation panel device 158.

  More specifically, the imaging mode selection images 201, 202, and 203 correspond to the panoramic imaging mode selection image 201 corresponding to the panoramic imaging mode, the cephalo imaging mode selection image 202 corresponding to the cephalo imaging mode, and the CT imaging mode. And a CT imaging mode selection image 203 to be selected.

  Here, the panoramic imaging mode is an imaging mode that is executed to acquire a single image along the dentition of the entire mouth (or a part of the mouth), and, for example, the swing support portion 124 is set in a predetermined range In this mode, X-ray imaging is performed in a rotated state. As a panoramic imaging mode selection image 201, an image representing the character "Pan" is displayed. An X-ray generator 126 and an X-ray detector 128 are used for panoramic imaging.

  The cephalo imaging mode is an imaging mode executed to perform head radiography, that is, cephalo imaging. For example, X-rays from a certain direction with respect to the head in a state in which the rotation support unit 124 is stopped rotating It is a mode to take a picture. As the cephalo shooting mode selection image 202, an image representing the characters "Ceph" is displayed. The above-described imaging mechanism for cephalography is used for head radiograph photography.

  The CT imaging mode is an imaging mode that is executed to obtain a tomographic image of the entire dentition (or a part of the dentition), for example, a mode in which X-ray imaging is performed in a state in which the turning support 124 is rotated. is there. As the CT imaging mode selection image 203, an image representing the characters "CT" is displayed. An X-ray generator 126 and an X-ray detector 128 are used for CT imaging.

  The images displayed as the shooting mode selection images 201, 202, and 203 are not limited to the above-described example, and may be, for example, illustrations or the like imaging each shooting mode.

  The display screen of the operation panel device 158 is provided with a touch detection unit as a two-dimensional position detection unit that detects a touch position on the display outer surface. Then, when the user touches one of the shooting mode selection images 201, 202, and 203, the touch detection unit accepts a selection operation on any one of the shooting mode selection images 201, 203, and 203. When this selection operation is accepted, one imaging mode selection image corresponding to the selection operation may be visually displayed distinguishably with respect to the other imaging region selection image. Thus, the main control unit 150 accepts the selection of the photographing mode. When one of the shooting mode selection images 201, 203, and 203 receives a selection operation for one of the shooting mode selection images 201, 203, and 203, the selected one of the shooting mode selection images 201, 203, and 203 has a different color ( It may be displayed in different color shades) to make it distinguishable from others.

  Further, on the operation panel device 158, an image 210 for specifying a shooting position is displayed. Here, an image showing a dental arch is displayed as the imaging position designation image 210. The photographing position designation image 210 is displayed large at the center of the display screen of the operation panel device 158. The imaging position designation image may be an X-ray image, for example, a cephalo image, obtained by separately imaging the subject who is actually X-rayed. An image 211 (here, a circle) indicating the imaging position is superimposed on the imaging position specification image 210 and displayed. An image 211 indicates a shooting position in the shooting position designation image 210. It may be considered that the imaging position designation image 210 and the image 211 indicating the imaging position constitute a scout image for imaging position setting.

  In FIG. 7, images 211, 211a and 211b of three sizes are shown. The image 211, which is the smallest circle, is an area for photographing a part of the dental arch (about 5-6 for the teeth on the front teeth side, about 2-3 for the teeth on the molars side) It shows. An image 211a, which is a circle of intermediate size, shows an area for photographing the entire dental arch. The image 211b, which is the circle of the largest size, shows an area for imaging the entire maxillofacial area (which may be an area including all the left and right teeth ranging from the anterior teeth to the molars and the temporomandibular joint). As the images 211, 211a, and 211b, one image having a size according to the setting by the imaging region setting image 234 described later is displayed.

  When the user touches a position where imaging is desired for the imaging position specification image 210, the setting of the imaging position in the imaging position specification image 210 is accepted. The setting of the photographing position may also be performed using a direction key or the like.

  Further, on the operation panel device 158, an irradiation mode setting image 220 for setting the irradiation mode is displayed. Here, the irradiation mode setting image 220 is an image that simulates a gear, and is displayed below the imaging mode selection image 201. When the user touches the main irradiation mode setting image 220, characters “low dose noise reduction mode” and “ON” and “OFF” are displayed as shown in FIG. When the user touches the word "ON", the "low dose noise reduction mode" is turned on, and the setting of the low dose mode is accepted. When the user touches the character "OFF", the setting of the high resolution mode is accepted. After the setting, after a predetermined time has passed, or by touching another area (for example, “low dose noise reduction mode” or the like), it is possible to set to return to the original display screen. By turning on the low dose noise reduction mode, the low dose mode can be selected, and the above noise reduction processing is performed so that strong noise does not get on even when low dose X-ray CT imaging is performed. It becomes a mode.

  In addition, on the operation panel device 158, as the imaging condition setting image corresponding to the CT imaging mode, an image 231 for setting a region of interest, an image 232 for selecting a patient size, an image for selecting a CT imaging position with mode 233, an image for imaging region setting 234, a scan mode selection image 235 is displayed. In the present embodiment, the images 231, 232, 233, 234, and 235 are displayed in the area on the right side of the display screen of the operation panel device 158. Depending on the setting contents of the region of interest setting image 231, the presence or absence of the display of the other images 232, 233, 234, and 235 may be changed or changed to another image.

  The region-of-interest setting image 231 is an image in which an illustration image of the region of interest is added to the side of the characters “ROI”. The user can set a region of interest (ROI) through the region of interest setting image. When the user touches the region of interest setting image 231, as shown in FIG. 9, a plurality of regions of interest setting image 231A, 231B, and 231C are displayed. The plurality of regions of interest setting images 231A, 231B, and 231C are a row of teeth setting image 231A having a dental arch as a region of interest, a temporomandibular joint setting image 231B having a jaw joint as a region of interest, and a maxillofacial region of interest And a craniofacial setting image 231C. In the state where the images 231A, 231B, and 231C are displayed side by side, the setting of the region of interest is accepted by the user touching any of the images for region of interest setting 231A, 231B, and 231C. It is possible to configure so that the content of the later-described image capturing area setting image 234 to be displayed changes depending on which one of the dentition setting images 231A, 231B, and 231C is selected.

  The patient size setting image 232 is an image for setting the physical constitution, and here, an image in which an illustration image showing the upper body and a character (here, “M”) showing the size are added to the side of the “Size” character. It is. The user can set the patient size (body size) through the patient size setting image 232. When the user touches the patient size setting image 232, a plurality of patient size selection images 232A, 232B, 232C, and 232D are displayed as shown in FIG. The plurality of patient size selection images 232A, 232B, 232C, and 232D include a plurality of patient size display illustration images representing upper body contours of different sizes. More specifically, the patient size selection image 232A is an image obtained by adding "c" (the initial letter of child) to the smallest patient size display illustration image, and the patient size selection image 232B is the next smaller patient "S" (small initials) is added to the size selection image, and the patient size selection image 232C is "M" (middle initials) in the next smaller patient size selection image. , And the patient size selection image 232D is an image in which "L" (the initial of large) is added to the largest patient size selection image. In the state where these images 232A, 232B, 232C, 232D are displayed side by side, when the user touches one of them, the setting of the patient size (physical size) is accepted. In particular, when the patient size selection image 232A is selected, the setting indicating that the physical size is a child is accepted, and when the patient size selection images 232B, 232C, and 232D are selected, the physical size exceeds that of children. The setting of the effect is accepted.

  The CT imaging position-added mode selection image 233 is an image for changing the mode for performing position setting. By operating the CT position-added mode selection image 233, it becomes possible to set the imaging region based on the panoramic image or the scout image in two directions in addition to the setting of the imaging position by the dental arch.

  The imaging area setting image 234 is an image for setting the size of the imaging area. Here, the imaging area setting image 234 is an illustration (for example, a cylindrical shape) that three-dimensionally represents the shape of the imaging area. And an image of numerical values (diameter, height, etc.) representing the size. When the user touches the photographing area setting image 234, as shown in FIG. 11, a plurality of photographing area setting images 234A to 234H are displayed. The imaging region setting images 234A to 234H are a plurality of CT imaging region candidate images representing different CT imaging region sizes. That is, the imaging area setting images 234A to 234H are for setting CT imaging areas having different diameters, heights, and imaging area shapes. Note that the display examples of the imaging region setting images 234A to 234H in FIG. 11 are display examples when the dentition setting image 231A is selected from the above-described region of interest setting image 231. For example, when the maxillofacial setting image 231C is selected from the region of interest setting image 231, the number of imaging region setting images 234 can be reduced, and the maxillofacial region can be imaged for the size of the region of interest 1 It is also possible to set only one setting and put valuations only on the height of the region of interest. Assuming a typical dental jaw size, the relatively narrow imaging area setting images 234A and 234B cover a range of 40 mm in diameter, and select and designate a local CT imaging mode in which approximately three teeth can be imaged. It is an image for The relatively wide imaging region setting images 234C, 234D, and 234E cover a range of about 80 mm in diameter, and are images for selecting and designating a CT imaging mode for almost all jaws. In addition, imaging area setting images 234F, 234G, and 234H for selecting and designating a wide area setting screen CT imaging mode are completely all teeth including the molar tooth portion by making the imaging area into a triangular shape with rounded corners. It is an image for performing selection specification of the imaging | photography area | region which makes a jaw a target. Then, when the user touches one of the displayed images 234A to 234H, the setting acceptance of the CT imaging area size is made. When the size setting acceptance is not changed, the process proceeds to the next process with the current region of interest. Incidentally, the numbers described above and below on the right of each illustration indicate that the upper side indicates the diameter (mm) of the region of interest and the lower side indicates the height (mm) of the region of interest. When the height of the region of interest is 80, the upper and lower jaws can be photographed, and when it is 40 or 50, it can be used for imaging only the upper jaw or the lower jaw, so that the radiation dose can be reduced. .

  Note that the imaging region setting image 234 can be changed depending on the setting of the region of interest setting image 231. For example, when it is set that the maxillofacial region is set as the region of interest, the imaging region setting image 234 sets the size covering the entire maxillofacial region, for example, a range of 150 mm in diameter as the imaging region. It can be considered to be an image of

  The scan mode selection image 235 is an image for setting the turning angle of the turning support 124 required for X-ray CT imaging. For example, X-ray CT imaging is performed by 180 ° turning or X-ray by 360 ° turning. It is an image for setting a mode as to whether to perform line CT imaging.

  On the operation panel device 158, an irradiation setting image 241, a tube voltage setting image 242, a tube current setting image 243, and a sensitivity setting image 244 are displayed as imaging condition setting images. Here, these images are displayed on the lower part of the operation panel device 158.

  The irradiation setting image 241 is an image in which the letter “M” representing manual setting is added below the letter “Exp”. Manually setting the tube voltage, tube current, resolution, etc. using the setting by the irradiation setting image 241, turning off the X-ray (set when performing rotation of the arm without irradiation, etc. Can be set. What is currently selected may be displayed by the content displayed under the word "Exp". If the letter "M" is displayed as shown, the current selection is a manual setting. When the character "M" is touched, another option may be displayed. For example, a manual setting, an automatic setting, and an X-ray off can be selected, and the character “M”, the character “A”, and the character “Off” may be displayed by this selection. As the automatic setting, it is conceivable to set a pattern for adding an intensity to the X-ray dose during X-ray imaging, and another character may be displayed when the pattern having this intensity is selected.

  When the manual setting is selected, the above-described low dose mode may be left, and the same irradiation condition may be applied regardless of imaging information such as an imaging region. For example, when manual setting is selected for a certain imaging region and the tube current is operated to be 8 mA, the same tube current 8 mA is applied even if the imaging region of another size is set. You may do so. Here, the mode to which the same irradiation condition is applied may be referred to as a multi-condition mode, and the low dose mode and the multi-condition mode may be configured to be selectable. Alternatively, at least one of the low dose mode, the high resolution mode, and the multi-condition mode may be selected. The selection may be performed by the operation on the irradiation mode setting image 220.

  The tube voltage setting image 242 is an image in which a number representing a tube voltage setting value is added under the character “kV” representing a tube voltage unit. When the user touches the tube voltage setting image 242, as shown in FIG. 12, a tube voltage adjustment image 242A is displayed. The adjustment image 242A of the tube voltage includes a symbol "+" for increasing the tube voltage, a symbol "-" for decreasing the tube voltage, and a numerical value display point indicating the tube voltage. When the user touches the symbol "+", the set value of the tube voltage increases, and when the symbol "-" is touched, the set value of the tube voltage decreases, and each set value becomes a numerical value. Is displayed. When the tube voltage adjustment image 242A is displayed, the character “OK” is displayed, and when the tube voltage setting is completed, touching the “OK” character part causes the tube voltage adjustment image 242A to be displayed. It disappears and the image 242 for tube voltage setting is displayed in the state where the said setting value was reflected.

  The tube current setting image 243 is an image in which a number representing a tube current setting value is added under “mA” representing a tube current unit. As shown in FIG. 13, when the user touches the tube current setting image 243, a tube current adjustment image 243A is displayed. The adjustment image 243A of the tube voltage includes a symbol "+" for increasing the tube current, a symbol "-" for decreasing the tube current, and a numerical value display point indicating the tube current. When the user touches the symbol "+", the set value of the tube current increases, and when the user touches the symbol "-", the set value of the tube current decreases, and each set value becomes a numerical value. Is displayed. When the tube current adjustment image 243A is displayed, the character “OK” is displayed, and when the tube current setting is completed, touching the “OK” character part causes the tube current adjustment image 243A to be displayed. It disappears and the tube current setting image 243 is displayed in the state where the above set value is reflected.

  The sensitivity setting image 244 is an image for manually setting the sensitivity per unit area of the detection surface of the X-ray detector 128. For example, the standard sensitivity and the high sensitivity may be selected so that the character "SD" is displayed in the standard case and the character "HR" is displayed in the high resolution.

  In addition, the display position of each said image is not restricted to the example shown in FIG. 7, It can set to arbitrary positions.

<Example of reference table>
An example of the reference table will be described with reference to FIG.

  In this reference table, the low dose mode and the high resolution mode are separately set. Moreover, in each mode, a child and an adult (body size over children) are set separately.

  Regarding the body size of an adult in the low dose mode, the output condition of the X-ray generator 126 is set to a tube voltage of 100 kV and a tube current of 8 mA when the diameter of the imaging region is 40 mm. In addition, the voxel size is set as 80 μm as a setting related to the image quality. The size of the imaging area may be set as the size of the imaging area in a plane (that is, a plane parallel to the floor) orthogonal to the pivot axis by the pivot drive unit 30. In the case where the imaging area on the surface is circular, it may be defined as the diameter of the circle, and in the case where the imaging area on the surface is non-circular, it may be defined as the diameter of the circumscribed circle to the imaging area.

  On the other hand, when the diameter of the imaging region is 80 mm or 100 mm, it differs in that the tube current is set to 7 mA as compared with the above output condition. Moreover, it differs also in the point set as voxel size as 125 micrometers as a setting regarding image quality.

  For this reason, when the diameter of the imaging region is 80 mm or 100 mm, the output condition is set such that the dose is smaller than in the case where the diameter of the imaging region is 40 mm. In addition, when the diameter of the imaging area is 80 mm or 100 mm, the voxel size is set larger as compared with the case where the diameter of the imaging area is 40 mm. As a result, the resolution is coarse but noise is reduced. Image quality is set.

  Furthermore, when the diameter of the imaging area is 150 mm, the tube current is set to 6 mA as compared with the case where the diameter of the imaging area is 40 mm, 80 mm or 100 mm. Moreover, it differs also in the point set as voxel size as 320 micrometers as a setting regarding image quality.

  For this reason, when the diameter of the imaging region is 150 mm, the output condition is set such that the diameter of the imaging region is smaller than that in each of the above examples. In addition, when the diameter of the imaging area is 150 mm, the voxel size is set larger compared to the above examples, and as a result, the resolution becomes coarser, but the image quality is further reduced with noise reduced. It is done.

  Here, assuming that the imaging area having a diameter of 40 mm is a first imaging area and the imaging area having a diameter of 80 mm or 100 mm is a second imaging area, the first output condition according to the size of the first imaging area The dose based on (tube voltage 100 kV, tube current 8 mA) is larger than the dose based on the second output condition (tube voltage 100 kV, tube current 7 mA) according to the size of the second imaging region (relatively Considering that the dose based on the second output condition is smaller than the dose based on the first output condition, each of the first output condition and the second output condition is defined. The X-ray output condition setting unit 152d automatically sets the first output condition and the second output condition based on the reference table 152 so that the above condition is satisfied.

  Also, assuming that a shooting area having a diameter of 80 mm or 100 mm is a first shooting area and a shooting area having a diameter of 150 mm is a second shooting area, the first output condition ((1) Consider (relatively considered) that the dose based on the tube voltage 100kV, tube current 7mA) is larger than the dose based on the second output condition (tube voltage 100kV, tube current 6mA) according to the size of the second imaging region And the first output condition and the second output condition are defined such that the dose based on the second output condition becomes smaller than the dose based on the first output condition. The X-ray output condition setting unit 152d automatically sets the first output condition and the second output condition based on the reference table 152 so that the above condition is satisfied.

  The imaging area having a diameter of 150 mm is set to use the maxillofacial area of the subject P as the imaging area, and the imaging area having a diameter of 40 mm is a first imaging area where some teeth of the dental arch fit. The imaging area having a diameter of 80 mm or 100 mm can be regarded as an example of the entire area of the dental arch or an area in which all the teeth of the dental arch fit.

  However, the size of each imaging area does not have to be the above example.

  For example, the case where a part of the dental arch is used as the imaging area and the case where the entire dental arch is used as the imaging area are distinguished according to the size of the imaging area will be considered. In this case, the imaging information reception unit 152c receives the setting of the imaging area in which the diameter of the boundary circle or circumscribed circle is R1 (mm) as the first imaging area, and the diameter of the boundary circle or circumscribed circle is in the second imaging area. Assuming that it is possible to accept the setting of the imaging region which is R2 (mm), R1 (mm) <k1 (mm) <R2 (R2 (mm) <R2 (R)) for a value k1 satisfying 40 (mm) It is good to satisfy the condition to satisfy mm).

  Further, for example, a case in which the case where the entire dental arch is taken as the imaging region and the case where the entire jaw is taken as the imaging region as possible is distinguished depending on the size of the imaging region. In this case, the imaging information reception unit 152c receives the setting of the imaging area in which the diameter of the boundary circle or circumscribed circle is R1 (mm) as the first imaging area, and the diameter of the boundary circle or circumscribed circle is in the second imaging area. Assuming that it is possible to accept the setting of the imaging region which is R2 (mm), R1 (mm) <k2 (mm) <R2 (R2 (mm) <R2 (m)) for a value k2 satisfying 80 (mm) <k2 (mm) <120 (mm). It is good to satisfy the condition to satisfy mm).

  In addition, regarding the physique of a child in the low dose mode, the tube voltage is set to be as small as 90 kV as compared with each of the above examples. Therefore, in the reference table 152, the output condition according to the physical size exceeding the child such that the dose based on the output condition according to the physical size exceeding the child is larger than the dose based on the output condition according to the physical size of the child And at least one setting value defining each output condition according to the physical constitution of the child. Therefore, based on the reference table 152, the X-ray output condition setting unit 152d causes the dose based on the output condition according to the physical size exceeding that of the child to be larger than the dose based on the output condition according to the physical size of the child At least one set value can be set automatically, which defines the output condition according to the physical size exceeding children and the output condition according to the physical size of children.

  The dose during X-ray CT imaging can be adjusted by the tube voltage, tube current, irradiation time of the X-ray generator 126, and the like. For example, if the irradiation time of the X-ray detector 128 is shortened, the dose will be smaller, and if the irradiation time is longer, the dose will be larger. The setting of the irradiation time can be adjusted, for example, by adjusting the speed at which the X-ray generator 126 is rotated. Also, the dose can be switched by adjusting the angle at which the X-ray generator 126 is turned (for example, switching the 180 ° rotation or the 360 ° rotation).

  The dose during X-ray CT imaging can be set theoretically, experimentally, and empirically by adjusting the tube voltage, tube current, irradiation time, and the like of the X-ray generator 126 in combination.

  Further, in the high resolution mode, the tube current is uniformly set to 8 mA as compared with the dose mode. In addition, the voxel size is uniformly set as 80 μm as a setting relating to the image quality. Therefore, in the high resolution mode, clear X-ray CT images can be obtained uniformly at relatively high dose. The tube current may be uniformly 9 mA, and a difference may be made between the low dose mode and the high resolution mode even in the imaging region having a diameter of 40 mm. The numerical values in the reference table may be accessible by the operator and may be arbitrarily modified.

  Also, for example, for the imaging region of 40 mm in diameter for adult physique in low resolution mode, the output condition in the case of the maxillary molar region is 100 kV tube voltage and 7.5 mA tube current, 40 mm diameter imaging for pediatric physique For the region, the output condition for the maxillary molar region may be weaker than that in the high resolution mode, such as a tube voltage of 90 kV and a tube current of 7.5 mA. As the tube current is weakened, the voxel size of the image quality setting may be expanded to 90 μm, for example.

  Furthermore, an output condition setting for each imaging region may be added. For example, for the imaging region with a diameter of 40 mm in the low resolution mode, the output condition for the maxillary molar region is 100 kV tube voltage and 8 mA tube current, and the output condition for the mandibular anterior region is 100 kV tube voltage and 5 mA tube current etc. , May change with each part.

<Operation>
The operation of the X-ray CT imaging apparatus 110 will be described focusing on the X-ray CT imaging operation with reference to FIG.

  First, in step S1, when the user touches one of the imaging mode selection images 201, 202 and 203, one of the panoramic imaging mode, the cephalo imaging mode and the CT imaging mode is selectively received (FIG. 7). reference). If the setting of the panoramic imaging mode is accepted, the process proceeds to step S11, where the panoramic imaging process is performed. If the setting of the cephalometric mode is accepted, the process proceeds to step S12, and the cephalometric process is performed. If the setting of the CT imaging mode is accepted, the process proceeds to step S2 and subsequent steps.

  In step S2, it is determined that the CT imaging mode is to be performed.

  In the next step S3, the setting of the irradiation mode is accepted using the irradiation mode setting image 220 or the like (see FIGS. 7 and 8).

  In the next step S4, the setting of the region of interest is accepted through the region-of-interest setting image 231 or the like (see FIG. 9).

  In the next step S5, the setting of the patient size (body size) is accepted through the patient size setting image 232 (see FIG. 10). As already mentioned, setting of the patient size (body size) includes setting of whether the body size is a child or a body size larger than a child.

  In the next step S6, setting with position is accepted through the photographing area setting image 234, the photographing position designation image 210 and the like (see FIG. 7). Thereby, the setting of the imaging position is accepted.

  In the next step S7, the size of the imaging area is set through the imaging area setting image 234 (see FIG. 11).

  In the next step S8, the output condition of the X-ray generator 126 is automatically set. Here, referring to the reference table 152 shown in FIG. 14, the output condition of the X-ray generator 126 is determined based on the size of the imaging region and whether the physical size is a child or a size larger than a child (that is, an adult). Set automatically.

  After the automatic setting, the process proceeds to step S9, and it is determined whether or not the output condition is set manually. If it is determined that the user has manually set the tube voltage and tube current through the tube voltage setting image 242, the tube current setting image 243, etc., the process proceeds to step S13, and the output condition is set based on the manual setting. And return to step S9. The determination of step 9 after step 8 is the determination of the presence or absence of the manual setting operation, and the determination of step 9 after step 13 is the determination of the presence or absence of the newly added manual setting operation.

  If it is determined in step S9 that the manual setting of the output condition is not present, the process proceeds to step S10.

  In step S10, X-ray CT imaging is performed according to the set output condition. An X-ray CT image is generated based on the data obtained by this. When generating an X-ray CT image, an X-ray CT image is generated according to the setting relating to the image quality (here, setting of the voxel size). The above steps can be changed as appropriate. For example, the order of step 6 and step 7 may be switched.

<Effects>
According to the medical X-ray CT imaging apparatus 110 configured as described above, the medical X-ray CT imaging condition setting method, and the X-ray CT imaging condition setting program 151a, the X-ray generator 126, the X-ray detector 128, The X-ray CT imaging apparatus 110 receives the setting of the imaging area regarding at least one of the size of the imaging area, the imaging purpose, and the imaging region in the X-ray CT imaging apparatus 110. By automatically setting the output condition of the X-ray generator 126 in accordance with at least one of the size of the imaging region, the imaging purpose, and the imaging region received, the exposure can be reduced as much as possible. Also, in general, the size of the imaging area or the imaging site is set according to the imaging purpose, the output of the X-ray generator 126 according to at least one of the imaging area size, the imaging purpose and the imaging site By automatically setting the conditions, it is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose.

  In addition, in the X-ray output condition aiming at low dose, noise tends to get on the X-ray CT image. By automatically setting the image quality of the X-ray CT image in accordance with at least one of the setting of the imaging region and the automatically set output condition of the X-ray generator 126, X-ray output conditions aimed specifically at low dose X When performing line CT imaging, noise can be reduced.

  In particular, by setting the size of the accepted imaging area to the size in the plane orthogonal to the turning axis, the output condition of the X-ray generator can be automatically set according to the spread of the imaging area on the plane. .

  Also, in general, if it is desired to observe details in detail, a relatively small imaging area is set, and if it is desired to perform an entire observation, a relatively large imaging area is set. Therefore, as a setting related to the size of the imaging area, the setting of the first imaging area and the second imaging area wider than the first imaging area is received, and the second output according to the size of the second imaging area At least one set value defining each of the first output condition and the second output condition such that the dose based on the condition is smaller than the dose based on the first output condition according to the size of the first imaging region If automatically set, X-ray CT imaging can be performed under appropriate output conditions according to the purpose.

  Also, considering the first imaging area and the second imaging area, if an area in which a part of teeth of the dental arch fits is set as the first imaging area, the first output with a relatively large dose Under the conditions, X-ray CT imaging can be performed, and it becomes possible to observe a part of teeth of the dental arch with a relatively clear image. On the other hand, when the whole area of the dental arch or an area in which all the teeth of the dental arch can be set is set as the second imaging area, the X-ray CT is performed under the second output condition in which the dose is relatively small. You can take pictures.

  In addition to the accepted imaging region, the exposure condition can be reduced as much as possible by automatically setting the output condition of the X-ray detector 128 according to the setting of the physique.

  Specifically, when the physical size is set to be a child, the dose can be reduced and the exposure dose can be reduced. On the other hand, if it is set that the physical size exceeds children, the dose can be increased to obtain a clear image.

  In addition, as the output condition of the X-ray detector 128, the dose is adjusted by automatically setting at least one of the tube voltage of the X-ray generator 126, the tube current, and the time during which the X-ray generator 126 emits X-rays. can do.

  In addition, it is possible to switch between the low dose mode and the high resolution mode, and when the low dose mode is received, the output condition of the X-ray generator is automatically set according to the received information on the imaging region, It is possible to obtain an X-ray CT image of an image quality as appropriate as possible according to the imaging purpose while achieving low exposure. In addition, when the high resolution mode is accepted, a clear X-ray CT image can be obtained regardless of the information on the accepted imaging region. Further, after the output conditions of the X-ray generator 126 are automatically set in accordance with the received information on the imaging region, the output conditions can be changed by manual setting in accordance with the preference of the operator.

  Here, a control example of the output condition of the X-ray generator 126 will be described from the side of the irradiation X-ray dose.

  As mentioned above, the detection surface of the X-ray detector 128 is composed of pixels. When each pixel is square, the shape of the X-ray beam irradiated to each pixel from the focal point of the X-ray tube is substantially square pyramidal. For example, when the tube current is increased, the irradiation X-ray dose contained in the space formed by the substantially square pyramidal X-ray beam for each pixel is increased, and when the tube current is decreased, the irradiation X-ray dose is decreased. Similarly, for example, when the tube voltage is increased, the irradiation X-ray dose contained in the space formed by the substantially square pyramidal X-ray beam for each pixel is increased, and when the tube voltage is decreased, the irradiation X-ray dose is decreased. Similarly, for example, when the irradiation time of X-rays is increased, the irradiation X-ray dose contained in the space formed by the substantially quadrangular pyramidal X-ray beam for each pixel when evaluated over the entire irradiation time increases. As the irradiation time is shortened, the irradiation X-ray dose as evaluated over the entire irradiation time decreases.

  Considering this on the X-ray detector 128 side, if there is no attenuating element such as an object between the X-ray generator 126 and the X-ray detector 128, the amount of light received by each pixel is assumed to be a tube current. It increases, and decreases as the tube current decreases. Similarly, the amount of light received by each pixel increases as the tube voltage increases, and decreases as the tube voltage decreases. Similarly, the amount of light received by each pixel increases as the irradiation time of the X-ray increases, and decreases as the irradiation time of the X-ray decreases. Further, if the irradiation conditions are not changed including the tube current, the tube voltage, and the irradiation time in a plurality of X-ray irradiations, the light reception amount of each pixel is the same.

  As described above, it is conceivable to change the output condition so as to increase or decrease the irradiation X-ray dose with respect to the unit area of the detection surface of the X-ray detector 128 (this is similar to the above-mentioned substantially square pyramidal spaces) It is also the increase and decrease of the X-ray dose passing through the unit space. Assuming that there is no attenuating element such as an object between the X-ray generator 126 and the X-ray detector 128, increasing or decreasing the irradiation X-ray dose per unit area of the detection surface of the X-ray detector 128 is X It is synonymous with increasing or decreasing the light reception amount per unit area of the detection surface of the line detector 128.

  As the unit area, an area of each pixel unit, an area of each binning unit when a plurality of pixels can be binned, and the like can be considered.

  Therefore, as an example of automatically setting the output condition of the X-ray generator according to at least one of the size of the imaging area received by the imaging information reception unit, the imaging purpose and the imaging region, an imaging area AR1 An example can be adopted in which the output of X-ray irradiation to the other imaging area AR2 is reduced with respect to the output of X-ray irradiation to the lens. For example, the tube current can be made lower for the imaging area AR2 than for the imaging area AR1, and the irradiation X dose per unit area can be made smaller for the imaging area AR2 than for the imaging area AR1 (provisionally, Assuming that the attenuating element such as the subject is retracted from between the X-ray generator 126 and the X-ray detector 128, the amount of light received per unit area is more for the imaging area AR2 than for the imaging area AR1. Will be smaller). Similarly, for example, the tube voltage can be lower for the imaging area AR2 than for the imaging area AR1, and the irradiation X dose per unit area can be smaller for the imaging area AR2 than for the imaging area AR1. Similarly, for example, the irradiation time can be shorter for the imaging area AR2 than for the imaging area AR1, and the irradiation X dose per unit area can be smaller for the imaging area AR2 than for the imaging area AR1. Of course, the combination of the tube current, the tube voltage and the irradiation time can be adjusted to make the irradiation X dose per unit area smaller than the imaging area AR2 with respect to the imaging area AR2.

  In addition, making the output of X-ray irradiation to the imaging area AR1 equal to the output of X-ray irradiation to the imaging area AR2 means making the irradiation X-ray dose per unit area the same (provisionally, X-ray generator Assuming that the attenuating element such as a subject is retracted from between 126 and the X-ray detector 128, the received light amount per unit area is the same unless the irradiation condition is changed including the tube current.

{Modification}
The modified example shown in FIG. 16 shows an example of a reference table in the case where the irradiation time is changed among the set values defining the output condition of the X-ray generator 126.

  As shown in the figure, the tube voltage is 100 kV and the tube current is 8 mA, which is the same between the size of the imaging range with a diameter of 40 mm and the size of the imaging range with a diameter of 80 mm or 100 mm. By setting the time to 17.9 s and the latter irradiation time to 9.4 s, the former is set to have a larger dose for X-ray CT imaging than the latter. Assuming that the turning angle of the X-ray detector 128 (or the turning support 124) is in the same range AG1, the time taken to turn this angle AG1 is switched to either the irradiation time 17.9 s or the irradiation time 9.4 s. The irradiation time may be changed by switching the turning angle of the X-ray detector 128 (or the turning support 124). For example, the turning angle is switched to either 360 ° or 180 °. In this case, setting the irradiation time to 17.9 s means that the turning angle of the X-ray detector 128 is 360 °, and setting the irradiation time to 9.4 s means that the turning angle of the X-ray detector 128 is 180 °. You may think that there is. For the size of the imaging range which is 150 mm in diameter, the irradiation time is set to 9.4 s, the tube current is 6 mA, and the tube current is lowered to reduce the diameter of the imaging range which is 80 mm or 100 mm. Also, the dose for X-ray CT imaging is set to be small.

  In the above embodiment, mainly the example in which the output condition of the X-ray detector 128 is set according to the size of the imaging range has been described, but the imaging information reception unit includes the size of the imaging area, the imaging purpose and the imaging region Setting the imaging area related to at least one of the X-ray generator according to at least one of the size of the imaging area, the imaging purpose and the imaging region received by the imaging information reception unit The output conditions of may be set automatically.

  For example, as shown in FIG. 17, in the operation panel device 158, a setting screen for photographing purpose is provided, and “・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Display a purpose selection image 300 that makes it possible to select the purpose, and a purpose selection image 302 that makes it possible to make it possible to observe “・ ・ ・ ・ ・ ・ ・ ・ ・When the user touches one of the purpose selection images 300 and 302, the main control unit 150 may receive the setting of the photographing purpose.

  Then, as shown in FIG. 18 as a reference table, clear X-ray CT imaging is performed when the imaging purpose of “a root fracture, endodontic therapy, apical lesion, bone regeneration process of an implant” is set. Since it is preferable to obtain an image, it is preferable to set an output condition where the dose is relatively large. Here, the tube voltage is set to 100 kV, and the tube current is set to 8 mA.

  In addition, when the purpose of imaging “・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・It is good to set to the output condition which becomes extremely small. Here, the tube voltage is set to 100 kV and the tube current is set to 6 mA.

  Thereby, the output condition of the X-ray generator 126 can be automatically set according to the set imaging purpose.

  Further, for example, as in the reference table shown in FIG. 19, the output condition of the X-ray detector 128 may be automatically set in accordance with the imaging region in the imaging range specified in the imaging position specification image 210. The designation of the region to be imaged may be performed by designation to an X-ray image captured in cephalography, as well as designation to the dental arch. The determination of the imaging region can be performed by determining the range of teeth included in the designated imaging range or the like.

  In this case, when the imaging site of “mandibular anterior teeth, mandibular molars, maxillary anterior teeth, maxillary molars” is set, the skull base with a large X-ray absorption coefficient does not enter in the X-ray cone beam path. In order to minimize the exposure dose, the dose is set to a relatively small output condition. Here, the tube voltage is set to 100 kV and the tube current is set to 6 mA.

  In addition, when an imaging site of “• temporomandibular joint” is set, the skull base enters in the path of the X-ray cone beam, and therefore, the output condition is set such that the dose becomes relatively large. The tube voltage is set to 100 kV, and the tube current is set to 8 mA.

  Thereby, the output condition of the X-ray generator 126 can be automatically set according to the set imaging region.

  Further, the output condition of the X-ray generator 126 may be automatically set in accordance with the size of the imaging region, the imaging purpose, and a plurality of combinations among the imaging regions. In this case, for example, as shown in FIG. 20, as the reference table, the imaging purpose and the imaging region are specified as needed for the size of the imaging region, and for each combination, the X-ray generator 126 It is sufficient to prepare an output condition and an image quality set. FIG. 21 shows an example in which the output condition of the X-ray generator 126 and the image quality are set for the combination of the imaging purpose and the imaging region with respect to the imaging region having a diameter of 40 mm. Also for the region, the output condition of the X-ray generator 126 and the image quality may be set for the combination of the imaging purpose and the imaging region.

  In addition, each structure demonstrated by said each embodiment and each modification can be combined suitably, as long as there is no contradiction mutually. For example, each part described in the second embodiment can be combined with the configuration described in the first embodiment.

  As mentioned above, although this invention was explained in detail, the above-mentioned explanation is illustration in all the aspects, and this invention is not limited to it. It is understood that countless variations not illustrated are conceivable without departing from the scope of the present invention.

10, 110 X-ray CT imaging apparatus 13 swing drive mechanism 20 support 22 X-ray generator 24 X-ray detector 30 swing drive unit 40 imaging information reception unit 60 X-ray output condition setting unit 60P X-ray CT imaging condition setting program 120 Imaging unit 121 Support column 123 Horizontal arm 124 Swing support unit 126 X-ray generator 128 X-ray detector 130 Swing drive mechanism 132 Swing mechanism 150 Main unit control unit 150a CPU
150c storage unit 150e operation input unit 150f image output unit 151 imaging program 151a X-ray CT imaging condition setting program 152 reference table 152a support unit drive control unit 152c imaging information reception unit 152d line output condition setting unit 152e output condition setting reception unit 152f X X-ray imaging data processing unit 152g X-ray detection unit drive control unit 152h X-ray generator drive control unit 152i image quality setting unit 158a code setting operation unit 158b imaging information setting operation unit 158c output condition setting operation unit 180 image processing device 181 control unit 181a image processing unit 182 information processing main unit 183 storage unit 220 irradiation mode setting image 231, 231A interest region setting image 231A dentition setting image 231B temporomandibular joint setting image 231C maxillofacial setting image 232, 232A, 23 B, 232C Patient size selection image 234, 234A, 234B, 234C, 234D, 234E, 234F, 234G, 234H Imaging region setting image 235 Scan mode selection image 241 Irradiation setting image 242 Tube voltage setting image 242A Adjustment image 243 tube current setting image 243A adjustment image 300, 302 purpose selection image E1, E2 shooting area P head (subject)

Further, the output condition of the X-ray generator 126 may be automatically set in accordance with the size of the imaging region, the imaging purpose, and a plurality of combinations among the imaging regions. In this case, for example, as shown in FIG. 20, as the reference table, the imaging purpose and the imaging region are specified as needed for the size of the imaging region, and for each combination, the X-ray generator 126 It is sufficient to prepare an output condition and an image quality set. FIG. 20 shows an example in which the output condition of the X-ray generator 126 and the image quality are set for the combination of the imaging purpose and the imaging region with respect to the imaging region having a diameter of 40 mm . Also for the region, the output condition of the X-ray generator 126 and the image quality may be set for the combination of the imaging purpose and the imaging region.

Claims (21)

An X-ray generator that generates a cone beam,
X-ray detector,
A support portion supporting the X-ray generator and the X-ray detector in an opposing state;
A pivot drive section for pivoting the X-ray generator supported by the support section and the X-ray detector;
An imaging information reception unit that receives setting of an imaging area regarding at least one of the size of the imaging area, the imaging purpose, and the imaging region;
An X-ray output condition setting unit that automatically sets an output condition of the X-ray generator according to at least one of the size of the imaging region, the imaging purpose, and the imaging region received by the imaging information reception unit;
Medical X-ray CT imaging apparatus equipped with The medical X-ray CT imaging apparatus according to claim 1, wherein
The image quality of the X-ray CT image is automatically set in accordance with at least one of the setting of the imaging region accepted by the imaging information accepting unit and the output condition of the X-ray generator set by the X-ray output condition setting unit. The medical X-ray CT imaging apparatus further comprising an image quality setting unit. The medical X-ray CT imaging apparatus according to claim 1 or 2, wherein
The medical X-ray CT imaging apparatus, wherein the imaging information reception unit receives setting of the size of the imaging region in a plane orthogonal to the turning axis by the turning drive unit as the setting regarding the size of the imaging region. The medical X-ray CT imaging apparatus according to any one of claims 1 to 3, wherein
The imaging information receiving unit can accept a setting of a first imaging area and a second imaging area wider than the first imaging area as the setting related to the size of the imaging area.
The X-ray output condition setting unit sets the dose based on the second output condition according to the size of the second imaging region smaller than the dose based on the first output condition according to the size of the first imaging region A medical X-ray CT imaging apparatus, which automatically sets at least one set value defining each of the first output condition and the second output condition. The medical X-ray CT imaging apparatus according to claim 4, wherein
The imaging information reception unit sets a maxillofacial area of the subject as an imaging area, a setting where a part of teeth of the dental arch is contained as the first imaging area, and the setting of the dental arch as the setting regarding the size of the imaging area. The medical X-ray CT imaging apparatus which can receive the setting which makes all the area | regions or the area | region where all the teeth of a dental arch fit can be set as the said 2nd imaging area. The medical X-ray CT imaging apparatus according to claim 4, wherein
The imaging information reception unit receives the setting of the imaging area in which the diameter of the boundary circle or circumscribed circle is R1 (mm) as the first imaging area, and the diameter of the boundary circle or circumscribed circle is in the second imaging area. It is possible to accept the setting of the imaging area which is R2 (mm),
Here, for a value k1 that satisfies 40 (mm) <k1 (mm) <70 (mm),
R1 (mm) <k1 (mm) <R2 (mm)
Meet the medical X-ray CT imaging device. The medical X-ray CT imaging apparatus according to claim 4, wherein
The imaging information reception unit receives the setting of the imaging area in which the diameter of the boundary circle or circumscribed circle is R1 (mm) as the first imaging area, and the diameter of the boundary circle or circumscribed circle is in the second imaging area. It is possible to accept the setting of the imaging area which is R2 (mm),
Here, for a value k2 that satisfies 80 (mm) <k2 (mm) <120 (mm),
R1 (mm) <k2 (mm) <R2 (mm)
Meet the medical X-ray CT imaging device. The medical X-ray CT imaging apparatus according to any one of claims 1 to 7, wherein
The photographing information receiving unit can receive the setting of the physical constitution,
The X-ray output condition setting unit may set the size of the imaging area received by the imaging information reception unit, the imaging purpose regarding the imaging purpose and the imaging area regarding at least one of the imaging regions, and A medical X-ray CT imaging apparatus, which automatically sets output conditions of the X-ray generator according to settings. The medical X-ray CT imaging apparatus according to claim 8, wherein
The imaging information reception unit receives, as the setting of the physical constitution, setting of whether the subject is a physical constitution of a child or a physical constitution exceeding a child,
The X-ray output condition setting unit sets the output condition according to the physical size exceeding the child so that the dose based on the output condition according to the physical size exceeding the child becomes larger than the dose based on the output condition according to the physical size of the child And a medical X-ray CT imaging apparatus that automatically sets at least one setting value that defines each of the output conditions according to the physical constitution of the child. The medical X-ray CT imaging apparatus according to any one of claims 1 to 9, wherein
The photographing information receiving unit receives the setting of the photographing purpose.
The medical X-ray CT imaging apparatus, wherein the X-ray output condition setting unit automatically sets an output condition of the X-ray generator according to the imaging purpose received by the imaging information receiving unit. The medical X-ray CT imaging apparatus according to any one of claims 1 to 10, wherein
The imaging information receiving unit receives the setting of the imaging site.
The medical X-ray CT imaging apparatus, wherein the X-ray output condition setting unit automatically sets an output condition of the X-ray generator according to the imaging region received by the imaging information reception unit. The medical X-ray CT imaging apparatus according to any one of claims 1 to 11, wherein
The X-ray output condition setting unit automatically sets, as an output condition of the X-ray generator, at least one of a tube voltage of the X-ray generator, a tube current, and a time during which the X-ray generator irradiates X-rays. Medical X-ray CT imaging system. The medical X-ray CT imaging apparatus according to any one of claims 1 to 12, wherein
It further has a mode setting acceptance unit that accepts settings for low dose mode and high resolution mode.
When the low dose mode is received by the mode setting receiving unit, the X-ray output condition setting unit outputs the output condition of the X-ray generator according to the imaging region received by the imaging information receiving unit. Medical X-ray CT imaging system to set automatically. The medical X-ray CT imaging apparatus according to any one of claims 1 to 13, wherein
The apparatus further comprises an output condition setting accepting unit that accepts manual setting of the output condition of the X-ray generator,
The X-ray output condition setting unit automatically sets the output condition of the X-ray generator according to the imaging region received by the imaging information reception unit, and then, according to the manual setting through the output condition setting reception unit A medical X-ray CT imaging apparatus, which changes the output condition of the X-ray generator. An X-ray generator that generates a cone beam,
X-ray detector,
A support portion supporting the X-ray generator and the X-ray detector in an opposing state;
A pivot drive section for pivoting the X-ray generator supported by the support section and the X-ray detector;
A medical X-ray CT imaging condition setting method for setting conditions for performing X-ray CT imaging in a medical X-ray CT imaging apparatus comprising:
Receiving the setting of the imaging area regarding at least one of the size of the imaging area, the imaging purpose, and the imaging site, the size of the accepted imaging area, the X according to at least one of the imaging purpose and the imaging site Medical X-ray CT imaging condition setting method that automatically sets the output conditions of the line generator. An X-ray generator that generates a cone beam,
X-ray detector,
A support portion supporting the X-ray generator and the X-ray detector in an opposing state;
A pivot drive section for pivoting the X-ray generator supported by the support section and the X-ray detector;
An X-ray CT imaging condition setting program for a medical X-ray CT imaging apparatus comprising
A computer for setting X-ray CT imaging conditions of the medical X-ray CT imaging apparatus;
(A) accepting the setting of the imaging area regarding at least one of the size of the imaging area, the imaging purpose, and the imaging region;
(B) automatically setting the output condition of the X-ray generator according to at least one of the size of the imaging area, the imaging purpose, and the imaging region received;
X-ray CT imaging condition setting program for executing. Medical X-ray CT imaging apparatus
An X-ray generator that generates a cone beam,
X-ray detector,
A support portion supporting the X-ray generator and the X-ray detector in an opposing state;
An actuator for pivoting the X-ray generator supported by the support and the X-ray detector;
Equipped with a processor and
The processor inputs the setting of the imaging area regarding at least one of the size of the imaging area, the imaging purpose and the imaging region as imaging information, and the size of the imaging area input when setting the X-ray CT imaging condition A medical X-ray CT imaging apparatus which automatically sets an output condition of the X-ray generator according to at least one of an imaging purpose and an imaging site. The medical X-ray CT imaging apparatus according to claim 17, wherein
The processor is capable of receiving information on settings of a first imaging area and a second imaging area wider than the first imaging area as the setting related to the size of the imaging area, and the size of the second imaging area Of the first output condition and the second output condition such that the dose based on the second output condition according to the magnitude is smaller than the dose based on the first output condition according to the size of the first imaging region Medical X-ray CT imaging apparatus that automatically sets at least one setting value that defines each. The medical X-ray CT imaging apparatus according to claim 17 or 18, wherein
The processor can receive information on settings for a first imaging purpose and a second imaging purpose as settings relating to the imaging purpose, and the first imaging purpose is for more detailed observation than the second imaging purpose. The first output such that the dose based on the second output condition according to the second purpose is smaller than the dose based on the first output condition according to the first purpose. A medical X-ray CT imaging apparatus, which automatically sets at least one set value defining each of the condition and the second output condition. The medical X-ray CT imaging apparatus according to any one of claims 17 to 19, wherein
The processor can receive information on settings of a first imaging site and a second imaging site as settings relating to the imaging site, and the first imaging site has a larger amount of hard tissue than the second imaging site. The density of the hard tissue is high, or the dose based on the second output condition according to the second imaging site is smaller than the dose based on the first output condition according to the first imaging site A medical X-ray CT imaging apparatus, which automatically sets at least one set value defining each of a first output condition and the second output condition. The medical X-ray CT imaging apparatus according to any one of claims 17 to 20, wherein
The medical X-ray CT imaging apparatus according to claim 1, wherein the processor automatically sets the image quality of the X-ray CT image in accordance with at least one of the input of the imaging region and the set output condition of the X-ray generator.

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