JP5986813B2 - Estimation apparatus, estimation method, and program for estimating enlargement ratio of image of region projected on X-ray image - Google Patents

Description

  The present invention relates to an estimation apparatus, an estimation method, and a program for estimating an enlargement ratio of an image of a portion projected on an X-ray image.

  In medical practice, artificial joint replacement is known in which a joint that has been damaged due to illness or injury is replaced with an artificial joint made of an artificial material. In artificial joint replacement, the size of a target part to be replaced with an artificial joint is measured by referring to an X-ray image acquired by X-ray imaging in order to determine the size of sockets, stems, etc. constituting the artificial joint. To do.

  In recent years, computer X-ray imaging using CR (Computed Radiography) or a flat panel detector (FPD) instead of X-ray film has become the mainstream in X-ray imaging.

  The CR is a system that uses an imaging plate (IP) placed in a cassette as an X-ray sensor. IP accumulates irradiated X-rays as energy. Then, in the CR reader, the X-ray energy that passes through the subject and is irradiated onto the IP is read by the optical laser, converted into a digital signal, and imaged. There are various sizes of cassettes, such as half-cut, large-angle, four-cut and six-cut.

  The FPD is a flat X-ray detector that detects X-ray energy that has passed through a subject and converts it into an electrical signal, and also functions as a film and a reader. In the FPD, there are an indirect conversion type in which X-rays are once converted into optical signals and then converted into electric signals, and a direct conversion type in which X-rays are directly converted into electric signals. The size of the FPD is basically only the maximum film size, and the position and range to be read are appropriately changed to the output image size.

  The digitalized X-ray image is subjected to image density and gradation processing by an image processing apparatus, and then stored in an image server called PACS (Picture Archiving and Communication System) in a hospital. The A terminal connected to a network in a hospital can refer to X-ray images at various places by accessing the PACS via the network.

The joint size is generally measured as follows.
A terminal connected to the hospital network accesses the PACS, acquires an X-ray image, and displays it on the display unit of the terminal. Then, referring to the X-ray image displayed on the display unit, the start point and the end point of the target part are designated, and the image pixel size of the necessary joint (for example, hip joint) is acquired. For example, a mouse or a touch pen is used to specify the start point and the end point. The joint size is estimated using information on the actual film size and image pixel size.

  By the way, in X-ray imaging, due to the mechanism, an image of a subject is recorded with an enlarged size than the actual size. This point will be described with reference to FIG.

  FIG. 1 shows the positional relationship between the focal point (X-ray generation source) 10 of the X-ray tube, the two subjects 11 and 12, and the image receiving surface 13 in X-ray imaging. FIG. 1 is an example in which the subject 11 is located farther from the image receiving surface 13 than the subject 12. In FIG. 1, an image 14 is an image of the subject 11 projected on the image receiving surface 13, and an image 15 is an image of the subject 12 projected on the image receiving surface 13. As shown in FIG. 1, as the subject moves away from the image receiving surface 13, the image of the subject projected on the image receiving surface 13 is enlarged and recorded.

  The joint is located inside the body. That is, even when the body is photographed so as to be in contact with the image receiving surface, the joint exists at a position away from the image receiving surface. Therefore, the image of the joint is recorded on the image receiving surface in a larger size than the actual joint size. Therefore, in measuring the size of the joint, it is necessary to correct the error due to this enlargement.

  As an error correction method, for example, there is a method of correcting the estimated size of the target portion while fixing the enlargement ratio to 10%. However, the distance of the target portion from the image receiving surface varies depending on the patient's body shape, for example, whether the patient is fat or thin. Even in the same patient, the distance from the image receiving surface is different between the hip joint and the spine. For this reason, in the method of performing correction while fixing the magnification rate uniformly at 10%, an error may occur in the magnification rate depending on the patient's body shape and target region, and it may be difficult to estimate the exact size.

  As a method of solving this problem, for example, there is a method of setting an enlargement ratio using a correction metal sphere (for example, Patent Document 1). In the method using the metal sphere for correction according to Patent Document 1, the metal sphere is arranged so that the distance from the image receiving surface to the target part and the distance from the image receiving surface to the metal sphere are the same.

  For example, when the target part is a hip joint, a metal ball for correction is arranged at the height of the patient's hip joint head. FIG. 2 (A) shows a front view when a correction metal ball 21 is arranged at the height of the hip joint head of the patient 20. 2B shows an image of the hip joint head 22, the correction metal ball 21, and the image received when the correction metal ball 21 is arranged at the height of the hip joint head 22, as shown in FIG. The positional relationship with the surface 23 is shown. FIG. 2C shows a correction metal sphere 21 and an image 24 of the metal sphere 21 projected onto the image receiving surface 23.

In the method of setting the enlargement ratio using the correction metal sphere, the enlargement ratio is calculated from the actual size of the metal sphere and the size of the image of the metal sphere. Specifically, as shown in FIG. 2C, when the diameter of the metal sphere 21 is d ₂ and the diameter of the image 24 of the metal sphere 21 is d ₁ , d ₁ / d ₂ is set as the enlargement ratio. To do.

JP-A-10-127614 JP 2009-142497 A

"Method of obtaining body thickness from weight and height", Journal of Japanese Society of Radiological Technology, 65th No. 1, pages 50-56

  However, in the conventional correction method described above, a metal ball for correction must be prepared, and the metal ball must be arranged for each radiographing according to the position of the target site of the patient. End up.

  The present invention has been made in view of the above points, and can estimate the magnification of the image of the portion projected on the X-ray image with higher accuracy while omitting the trouble of X-ray examination imaging. An object is to provide an estimation device, an estimation method, and a program.

  One aspect of the estimation apparatus according to the present invention is an estimation apparatus that estimates an enlargement ratio that is required when correcting the size of an image of a target region of a patient projected on an image receiving surface in X-ray imaging, A distance estimating means for estimating a distance between the target region and the image receiving surface based on a body thickness of the patient; a distance between the target region and the image receiving surface; a focal point of an X-ray tube; And an enlargement ratio estimating means for estimating the enlargement ratio based on the distance to the image receiving surface.

  According to this configuration, since the distance between the target part and the image receiving surface is estimated based on the patient's body thickness without using the metal sphere as a marker, the metal sphere is arranged according to the target part. Compared to the conventional method of estimating the enlargement ratio by simultaneously imaging the target region and the metal sphere, it is possible to save the trouble at the time of imaging. Further, since the enlargement ratio is estimated according to the body thickness corresponding to the patient's body shape, the enlargement ratio can be estimated with higher accuracy. Moreover, the size of the target part can be estimated with higher accuracy by using the enlargement ratio.

  In one aspect of the estimation apparatus according to the present invention, the distance estimation unit includes a position information table in which each part and position information of each part with respect to the body thickness are associated with each other. Position information associated with a part is acquired, and a distance between the target part and the image receiving surface is estimated based on the body thickness and the position information.

  According to this configuration, since the enlargement ratio is estimated according to the position of the target part with respect to the body thickness, the enlargement ratio can be estimated with higher accuracy for each target part.

  In one aspect of the estimation apparatus according to the present invention, the distance estimation unit includes a position information table in which each part is associated with position information indicating the position of each part in a predetermined coordinate system with the center of the body as the origin. And acquiring position information associated with the target part from the position information table, and determining a distance between the target part and the image receiving surface based on the body thickness, the position information, and the imaging direction. presume.

  According to this configuration, the distance between the image receiving surface and the target part can be calculated in various imaging directions.

  One aspect of the estimation apparatus according to the present invention further includes input means for receiving position information of the target part with respect to the body thickness, and the distance estimation means is based on the body thickness and the input position information. The distance between the target region and the image receiving surface is estimated.

  According to this configuration, the enlargement ratio is estimated by specifying the position of the target part with respect to the patient's body thickness using the results of examinations received by the patient in the past. Can be estimated.

  One aspect of the estimation apparatus according to the present invention further includes body thickness acquisition means for acquiring the body thickness of the patient.

  According to this configuration, since the enlargement ratio is estimated using the body thickness for each patient, the enlargement ratio can be estimated with higher accuracy.

ここで、α、βは、定数である。 In one aspect of the estimation apparatus according to the present invention, the body thickness acquisition unit holds a body thickness correction coefficient table in which a part, a body position, a body thickness direction, and a body thickness correction coefficient (f) are associated with each other. From the body thickness correction coefficient table, any one body thickness correction coefficient (f) is acquired according to the target region, the body position at the time of imaging, and the imaging direction, and the height (H) of the patient and the patient The body thickness (BT) is estimated from the body weight (W), the acquired body thickness correction coefficient (f), and the equation (1).

Here, α and β are constants.

  According to this configuration, it is possible to estimate the enlargement ratio of the image of the portion projected on the X-ray image with higher accuracy while saving time and labor during X-ray inspection imaging.

  In one aspect of the estimation apparatus according to the present invention, the body thickness acquisition unit acquires the height and weight information of the patient from the incidental information of the X-ray image.

  According to this configuration, since the body thickness can be estimated using existing information, an increase in cost or the like for estimating the body thickness can be suppressed.

  One aspect of the estimation apparatus according to the present invention further includes input means for receiving information on the height and weight of the patient.

  According to this configuration, the body thickness can be estimated even when information on the patient's height and weight is not added to the information about the patient added to the X-ray image.

  One aspect of the estimation apparatus according to the present invention is a size correction unit that corrects a size of an image of the target part projected on the image receiving surface using the magnification factor, and estimates an actual size of the target part. Furthermore, it comprises.

  According to this configuration, since the size of the actual target portion is estimated using the enlargement rate estimated with higher accuracy, the size of the actual target portion can be estimated with higher accuracy.

  One aspect of the estimation method according to the present invention is an estimation method for estimating an enlargement ratio necessary for correcting the size of an image of a part of a patient projected on an image receiving surface in X-ray imaging, On the basis of the body thickness, the distance between the target region and the image receiving surface is estimated, the distance between the target region and the image receiving surface, the focal point of the X-ray tube and the image receiving surface The enlargement ratio is estimated based on the distance between them.

  In one aspect of the program according to the present invention, an X-ray imaging apparatus includes an estimation apparatus that estimates an enlargement ratio that is necessary when correcting the size of an image of a patient's part projected on an image receiving surface. A distance estimating means for estimating a distance between the target region and the image receiving surface, a distance between the target region and the image receiving surface, a focal point of the X-ray tube, and the image receiving surface. Based on the distance between the two, it functions as an enlargement rate estimation means for estimating the enlargement rate.

  According to these, since the distance between the target part and the image receiving surface is estimated based on the patient's body thickness without using the metal sphere as a marker, the metal sphere is arranged according to the target part, Compared to the method of photographing the target part and the metal sphere at the same time and estimating the enlargement ratio, it is possible to save the trouble at the time of photographing. Further, since the enlargement ratio is estimated according to the body thickness corresponding to the patient's body shape, the enlargement ratio can be estimated with higher accuracy. Moreover, the size of the target part can be estimated with higher accuracy by using the enlargement ratio.

  According to the present invention, it is possible to estimate an enlargement ratio of an image of a portion projected on an X-ray image with higher accuracy while saving time and labor during X-ray examination imaging.

Illustration for explaining problems in X-ray imaging The figure which shows the example of arrangement | positioning of the metal ball in the case of acquiring the X-ray image of a hip joint The figure which shows the example of composition of the radiation department system The figure which shows the internal structural example of the site | part size estimation apparatus which concerns on embodiment of this invention The figure which shows an example of a body thickness correction coefficient table Diagram for explaining location information The figure which shows an example of a positional infomation table Diagram for explaining the enlargement ratio estimation method The flowchart which shows an example of the process in the case of estimating the size of an object part The figure for demonstrating the method of estimating the site | part size at the time of an oblique direction imaging | photography The figure which shows an example of a positional infomation table The figure for explaining the correction method of the enlargement ratio The figure which shows the implementation example of the site | part size estimation apparatus which concerns on embodiment of this invention

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The site size estimation apparatus according to the present invention is suitable for measuring the size of a patient site.

(Configuration example of hospital system)
First, a hospital system to which a part size estimation apparatus according to an embodiment of the present invention is applied will be described. The hospital system described below is an example, and the present invention can be applied to systems other than those shown here.

  FIG. 3 is a diagram illustrating an example of a configuration of a hospital system. As shown in FIG. 3, the hospital system includes a hospital information system (HIS) 100, a radiation department system 200, a terminal 300, a part size estimation device 400, an arbitrary data server (not shown), and an arbitrary Other department systems (not shown) are connected via a network 500. The network may be a local network such as a LAN (Local Area Network) or a global network such as the Internet. The other department system is a system of a department other than the radiation department, that is, a system of another inspection department, a system of an accounting department, or the like.

  A hospital information system (HIS) 100 is a system that manages information in a hospital in an integrated manner, including an order entry system, an electronic medical record system, a medical accounting system, and the like. The hospital information system (HIS) 100 receives the input of the patient's doctor in charge, generates order information including request contents for image diagnosis and imaging, information about the patient (hereinafter referred to as patient information), and the like. The information is notified to a radiation information system (RIS) 210 (to be described later) via the internal network 500.

  The radiation department system 200 includes a radiation information system (RIS) 210, a modality 220, and an image data server (PACS) 230. As shown in FIG. 3, these are connected via a network 500. The network may be a local network such as a LAN (Local Area Network) or a global network such as the Internet.

  The radiation information system (RIS) 210 is a system that performs overall management of information in the radiology department by performing examination reservations in the radiology department, management of examination result information relating to imaging examinations, management of material inventory information, and the like. . The radiation information system (RIS) 210 receives and records the order information transmitted from the hospital information system (HIS) 100. Further, the radiation information system (RIS) 210 transmits the order information to the modality 220 based on the order information, and further notifies the hospital information system (HIS) 100 of the examination execution information of the corresponding examination.

  The modality 220 is a generic name for an apparatus for performing X-ray inspection, CT (Computed Tomography) inspection, MRI (Magnetic Resonance Imaging) inspection, and the like, and a system group for performing image processing of captured images. For example, the modality 220 for performing X-ray inspection is obtained as an X-ray tube that is an X-ray generation source, IP or FPD that is an X-ray sensor, and a reading device (not shown) that reads data stored in the IP or FPD. And an image processing device (not shown) that performs density adjustment and gradation processing of the image. These components can take various forms depending on the type of examination and the configuration of the imaging room or modality in the hospital.

  For example, in an examination for performing an X-ray examination, an affected area of a patient is imaged using an IP or FPD that receives an X-ray outputted from an X-ray tube. Thereafter, an image of the affected area photographed using IP or FPD is converted into image data using a reader. The image recorded on the IP is converted into an image by irradiating with an optical laser. When an FPD is used, the FPD generates an image from a signal obtained by converting light generated by absorption by a phosphor into electric charge by a photodiode.

  The generated image is attached with supplementary information related to the image data based on the order information received from the radiation information system (RIS) 210. At this time, as a format of the inspection image generated by the modality 220, a format defined by DICOM (Digital Imaging and Communication in Medicine) which is a standard for medical images can be used. This DICOM is a standard for medical image format and other communication of medical information, and various devices support DICOM, thereby enabling medical departments to handle medical images.

  Further, the generated inspection image is subjected to image processing such as image density and gradation processing in an image processing apparatus, and the inspection image after image processing is transmitted to an image data server (PACS) 230.

  The image data server (PACS) 230 is a system that receives an inspection image after image processing and stores and manages the inspection image. As described above, the image data server (PACS) 230 is connected to the network 500 in the hospital. For this reason, terminals in various departments of the hospital can connect to the image data server (PACS) 230 via the network 500 and obtain necessary examination images at various locations.

  The terminal 300 is a terminal installed in various departments in a hospital, and a doctor in charge, a nurse, or the like inputs a medical history of a patient or receives an examination image acquired from an image data server (PACS) 230. It is a terminal that displays and is used for interpretation.

  The site size estimation apparatus 400 estimates the size of the target site of the patient using the X-ray image. The part size estimation apparatus 400 will be described later.

  Heretofore, an example of a hospital system to which the part size estimation apparatus according to the embodiment of the present invention is applied has been described.

(Part size estimation device)
Next, the part size estimation apparatus according to the embodiment of the present invention will be described.

  A part size estimation apparatus according to an embodiment of the present invention is an apparatus that estimates the size of a target part of a patient using an X-ray image among examination images generated by the above-described modality 220. 3 is applied to the part size estimation apparatus 400 shown in FIG. 3 may be configured to have the function of the part size estimation device 400.

  FIG. 4 is a diagram showing an internal configuration example of the part size estimation apparatus 400 according to the embodiment of the present invention. As shown in FIG. 4, the part size estimation apparatus 400 includes an image confirmation unit 410 that confirms an X-ray image, a part size calculation unit 420 that calculates the size of an image of a target part on the image receiving surface, and the patient's body thickness. A body thickness acquisition unit 430 that acquires information on the image, a distance estimation unit 440 that estimates the distance between the target region and the image receiving surface at the time of imaging, and the size of the image of the target region projected on the image receiving surface An enlargement factor estimation unit 450 that estimates an enlargement factor that is necessary at the time, a part size correction unit 460 that estimates the size of the target part by correcting the size of the image of the target part projected on the image receiving surface, and an input Part 470.

  The image confirmation unit 410 includes an image acquisition unit 411 and an image reference unit 412. The image acquisition unit 411 acquires an X-ray image of the patient from the image data server (PACS) 230 via the network 500, and the image reference unit 412 displays the acquired X-ray image. Hereinafter, the X-ray image displayed on the image reference unit 412 is referred to as a reference image.

The part size calculation unit 420 measures an image pixel size (hereinafter referred to as a reference size) of the image of the target part displayed on the image reference unit 412. For example, site size calculation unit 420, converts the distance from the starting point d _s of the target site to the end point d _e to the image pixel size in the reference image, a reference size d _0. Particular starting point _{d s} and the end point _{d e} is carried out, for example, using the input unit 470 to be described later (keyboard, mouse, touch pen, a touch panel, buttons, etc.). A method for obtaining information of the start point d _s and the end point d _e of sites in the reference image is not particularly limited.

Then, the part size calculation unit 420 calculates the size d of the image of the target part projected on the image receiving surface such as IP or FPD from the reference size, the entire size of the reference image, and the entire size of the image receiving surface (IP or FPD or the like). ₁ is calculated. Specifically, the part size calculation unit 420 calculates the size d ₁ of the image of the target part on the image receiving surface using the following relational expression.
d ₁ = d ₀ × R

Here, as shown below, the ratio R is the ratio of the overall size of the image receiving surface (such as IP or FPD) to the overall size of the reference image. That is,
R = total size of the image receiving surface / total size of the reference image.

Then, the part size calculation unit 420 outputs information on the calculated image size d ₁ of the target part to the part size correction unit 460.

  The body thickness acquisition unit 430 acquires information on the patient's body thickness. Hereinafter, a method for acquiring body thickness information in the body thickness acquisition unit 430 will be described.

  In X-ray imaging, the dose is adjusted in order to minimize the exposure dose of the patient. At this time, a method of adjusting the irradiation dose using the information on the body thickness is known.

式（２）において、ＢＴ（ｃｍ）は、体厚（Body Thickness）を示し、Ｗ（ｋｇ）は、体重（Weight）を示し、Ｈ（ｃｍ）は、身長（Hight）を示す。また、fは、体厚補正係数であって、部位、体位及び撮影方向に対応付けられた係数である。なお、非特許文献１では、体厚補正係数ｆの変動が最小となる（α、β）の組み合わせとして、（０．６、−０．８）が提案されている。 For example, Non-Patent Document 1 proposes a method of calculating body thickness using Equation (2) based on the height, weight, and body thickness correction coefficient of a patient.

In the formula (2), BT (cm) represents body thickness (Body Thickness), W (kg) represents body weight (Weight), and H (cm) represents height (Hight). Further, f is a body thickness correction coefficient and is a coefficient associated with the part, body posture, and imaging direction. Non-Patent Document 1 proposes (0.6, −0.8) as a combination of (α, β) that minimizes the variation in the body thickness correction coefficient f.

  When calculating and acquiring the body thickness using the above equation (2), the body thickness acquisition unit 430 associates the part, the body position, the imaging direction, and the body thickness correction coefficient f in advance. (Hereinafter referred to as a body thickness correction coefficient table).

  FIG. 5 is a diagram illustrating an example of the body thickness correction coefficient table. In FIG. 5, the imaging direction represents information indicating the orientation of the patient's body with respect to the image receiving surface at the time of imaging, that is, whether the body thickness indicates the thickness in the front-rear direction or the side direction of the body. , AP indicates that the body thickness is the thickness in the front-rear direction (Anterior Posterior), and LAT indicates that the body thickness is the thickness in the lateral direction. Each numerical value indicates a body thickness correction coefficient f. In addition, for the imaging of the chest and abdomen, the body thickness in the standing position and the body thickness in the prone position may differ greatly, and therefore a body thickness correction coefficient f is associated with each patient position. Yes.

  The body thickness acquisition unit 430 can acquire information on the patient's height, weight, target region, body position at the time of imaging, and imaging direction from the incidental information of the X-ray image. For example, photographing item information such as device type, patient information, and examination information is added to the DICOM information as supplementary information of the examination image. Here, the patient information includes information about the patient, such as the patient's name, date of birth, sex, blood type, height and weight. The examination information includes information on the examination performed by the modality 220, that is, examination number, which is a number for identifying the examination, information on the photographing date, photographing time, photographing part, posture at photographing, photographing direction, and the like. include.

  Then, the body thickness acquisition unit 430 acquires the body thickness correction coefficient f from the body thickness correction coefficient table based on the information on the target part, the body position at the time of imaging, and the imaging direction. For example, when the target part is a hip joint, the body thickness obtaining unit 430 obtains 100.22 associated with the part: hip joint, body thickness direction: front and rear (AP) as the body thickness correction coefficient f. Further, when the target site is the chest, the body position at the time of imaging is standing, and the imaging direction is AP, the body thickness acquisition unit 430 performs the following operation: site: chest, body position: standing position, body thickness direction: front and back ( 103.32 associated with (AP) is acquired as the body thickness correction coefficient f.

  And body thickness acquisition part 430 calculates body thickness using a formula (2) based on a patient's height, weight, and a body thickness correction coefficient.

  In this way, the body thickness acquisition unit 430 can estimate the body thickness using information included in the incidental information of the X-ray image.

  When the patient information does not include height and weight information, the patient height and weight information may be input to the input unit 470 described later.

  In addition, when the patient information is confirmed in advance during X-ray imaging and it is confirmed that the patient information does not include height and weight information, the patient height and weight information may be added to the patient information. Good. For example, when it is confirmed that the height and weight information necessary for calculating the body thickness is not included in the patient information at the time of imaging, the height and weight of the patient are measured before or after X-ray imaging. However, height and weight information may be added to the patient information. Alternatively, height and weight information may be acquired from a system connected to the network 500 such as the hospital information system 100 and the radiation information system 210 and added to the patient information. At this time, the acquisition source system may be provided with transmission means for transmitting the height and weight information, and the body thickness acquisition unit 430 may receive the information.

  In addition, if the height and weight information can be determined to be old from the measurement date of height and weight included in the patient information, the latest information on the height and weight of the patient can be input, or before X-ray imaging. Alternatively, the height and weight of the patient may be measured later, and the height and weight information may be added to the patient information. In this case, the body thickness acquisition unit 430 can estimate the body thickness using information on the latest height and weight of the patient, so that the estimation accuracy of the body thickness can be improved.

  In addition, before or after X-ray imaging, the patient's body thickness may be measured and information on the measured body thickness may be added to the patient information. In addition, before measuring the length of the target region, information on the patient's body thickness may be input to the input unit 470 described later.

  The body thickness acquisition method is not limited to the above method, and the body thickness acquisition unit 430 calculates the body thickness using a histogram of an X-ray image, for example, as proposed in Patent Document 2. May be. In X-ray imaging, the dose is adjusted using information on body thickness in order to minimize the exposure dose of the patient. For this reason, various methods other than the methods proposed in Patent Document 1 and Patent Document 2 have been studied as body thickness estimation methods. Therefore, the body thickness acquisition unit 430 may acquire body thickness information using a method other than that proposed in Patent Document 1 and Patent Document 2.

  In this manner, the body thickness acquisition unit 430 acquires information on the body thickness of the patient, and outputs the acquired information on the body thickness to the distance estimation unit 440.

  The distance estimation unit 440 estimates the distance between the target part at the time of imaging and the image receiving surface. Specifically, the distance estimation unit 440 has a correspondence table (hereinafter referred to as a position information table) in which a part and information on the position of the part with respect to body thickness (hereinafter referred to as position information) are associated with each other. Position information associated with the target part is acquired from the information table, and a distance between the target part and the image receiving surface is estimated based on the body thickness and the position information.

First, the position information (position information) with respect to the body thickness will be described with reference to FIG. FIG. 6 shows a horizontal view of a patient including a target portion when X-ray imaging is performed with the patient facing the focal point (X-ray generation source) 600 of the X-ray tube and the back side 640 facing the image receiving surface 610. It is an example of sectional drawing. Here, BT is the body thickness, and H ₁ is the distance from the back side 640 to the target region 620. In this case, the position information r is
r = H ₁ / BT
Is defined.

Alternatively, using the body thickness BT and H ₂ that is the distance from the front side 650 to the target site 620, the position information r is
r = H ₂ / BT
You may define as follows.

That is, in the position information r, the distance (H ₁ or H ₂ ) from either one end (side) to the target part of the two ends of the distance indicated by the body thickness BT occupies the body thickness BT. It is a ratio.

  The position information r is set in advance, for example, by extracting position information of each part from a large number of CT examination images and calculating an average value of the position information for each part. And the position information r obtained in this way is stored in the position information table.

  FIG. 7 is a diagram illustrating an example of the position information table. FIG. 7 is an example in which the position information r is associated with the part, the body position, and the position reference information. Here, the position reference information indicates whether the position information r is defined using the distance from the end (side) to the target part among the front side, back side, right side or left side of the patient. Show.

For example, when the position reference information is A (Anterior), the position information r indicates the ratio (H ₂ / BT) between the distance from the front side to the target part and the body thickness BT. When the position reference information is P (Posterior), the position information r indicates a ratio (H ₁ / BT) between the distance from the back side to the target part and the body thickness BT. When the position reference information is R (Right), the position information r indicates the ratio between the distance from the right side to the target part and the body thickness BT. When the position reference information is L (Left), the position information r indicates the ratio between the distance from the left side to the target part and the body thickness BT.

In the same part, the position information ra with position reference information A and the position information rp with position reference information P have a relationship of ra + rp = 1. For example, in the position information table of FIG. 7, the position information r ₀₁ and r ₀₂ of the chest has a relationship of r ₀₁ + r ₀₂ = 1. The hip joint position information r ₀₇ and r ₀₈ has a relationship of r ₀₇ + r ₀₈ = 1. Therefore, the position information table may store only one of the position information ra and rp of the same part.

  The position information of each part also depends on the patient's body shape. For example, the position of the hip joint relative to the body thickness differs between a person who is fat around the stomach and a person who is thin around the stomach. Therefore, the body shape may be divided into a plurality of groups, and a position information table may be created for each group.

  When the distance estimation unit 440 has a position information table for each body type, the patient may be classified into any body group at the time of X-ray imaging, and the body group information may be added to the incidental information. Alternatively, when measuring the length of the target region via the input unit 470 described later, a patient body group may be designated.

  Then, the distance estimation unit 440 selects a position information table optimal for the patient according to the information on the body group added to the incidental information or the information on the body group notified from the input unit 470. Thus, by using the position information table corresponding to the patient's body shape, the distance estimation unit 440 can acquire position information suitable for the patient.

The distance estimation unit 440 can acquire information on the target region, the patient's body position at the time of imaging, and the imaging direction from the incidental information of the X-ray image. And the distance estimation part 440 acquires the positional information on the acquired object part from a positional information table. For example, when the target part is a hip joint and the imaging direction is AP, the back surface of the patient is in contact with the image receiving surface, and therefore the distance estimation unit 440 obtains r ₀₈ whose position reference information is P as the position information r. To do. In addition, when the target site is the chest, the patient's body position at the time of imaging is standing, and the imaging direction is AP, the back surface of the patient is in contact with the image receiving surface. , R ₀₂ whose position reference information is P is acquired.

  If only one of the position information ra where the position reference information is A or the position information rp where the position reference information is P is stored in the position information table, the distance estimation unit 440 determines that ra + rp = From position 1, the position information ra and rp may be acquired.

Then, the distance estimation unit 440 estimates the distance H ₁ between the target part and the image receiving surface based on the body thickness BT of the patient and the position information r corresponding to the target part. For example, when the target part is a hip joint and the imaging direction is AP, the distance estimation unit 440 acquires _r08 as position information, and the hip joint exists at a position (BT × _r08 ) from the back of the patient. Determination is made, and the distance H ₁ between the hip joint and the image receiving surface is estimated as (BT × r ₀₈ ).

  The distance estimation unit 440 may use position information of the target part with respect to the body thickness of the target patient for which the size of the part needs to be measured. For example, the target patient may have performed a CT examination or the like in the past. In such a case, the position information of the target part may be acquired from the CT examination image of the target patient and input from the input unit 470 described later. Then, using the information received by the input unit 470, the distance estimation unit 440 may estimate the distance between the target region and the image receiving surface.

  Alternatively, position information of the target part may be acquired from the CT examination image at the time of CT examination, and the position information may be added to the incidental information of the X-ray image.

  In addition, when the artificial joint replacement is actually performed, the size of the target site of the patient is measured, and the size of the target site is calculated from the actual size of the target site and the size of the image of the target site projected on the image receiving surface. The position information may be calculated and the position information table may be updated. By updating the position information table based on the actual measurement data, the distance estimation unit 440 can acquire more reliable position information, and the estimation accuracy of the distance between the target region and the image receiving surface can be increased. Can be improved.

  In this way, when the distance estimation unit 440 can use position information unique to the target patient, the distance between the target portion and the image receiving surface can be estimated with higher accuracy.

  When the distance estimation unit 440 estimates the distance between the target part and the image receiving surface based on the body thickness and the position information of the target part with respect to the body thickness, the distance estimation unit 440 obtains information on the distance between the target part and the image receiving surface. The result is output to the enlargement rate estimation unit 450.

  The enlargement factor estimation unit 450 estimates an enlargement factor necessary for correcting the size of the image of the target portion projected on the image receiving surface. With reference to FIG. 8, an enlargement rate estimation method in the enlargement rate estimation unit 450 will be described. 8 that are the same as those in FIG. 6 are denoted by the same reference numerals. FIG. 8 is a diagram showing the positional relationship among the focal point (X-ray generation source) 600 of the X-ray tube, the target portion 620, and the image receiving surface 610. Note that the image 660 is an image of the target portion 620 projected onto the image receiving surface 610.

In FIG. 8, H ₃ is the distance between the focal point 600 and the target region 620. H ₁ is a distance between the target region 620 and the image receiving surface 610, and is estimated by the distance estimation unit 440 based on the body thickness. The enlargement ratio estimation unit 450 acquires information about the distance between focal films (FFD: Focus-Film Distance) from the incidental information of the X-ray image. As shown in FIG. 8, FFD is the sum of distance H ₁ and distance H ₃ .

The enlargement ratio estimating unit 450 from the focal film distance (FFD) and the distance _{H 1} Tokyo, using equation (3), to estimate the magnification M.

As can be seen from the equation (3) and FIG. 8, the enlargement ratio M is the ratio of the size d ₁ of the target part image 660 projected on the image receiving surface to the size d ₂ of the actual target part 620 of the patient. Then, the enlargement rate estimation unit 450 outputs information on the estimated enlargement rate M to the part size correction unit 460.

  In the radiographer method, it is obliged to record FFD information in an irradiation record as an imaging (irradiation) condition. Therefore, the FFD information may be input by the modality 220 before and after the image capture or when the FFD information is recorded in the irradiation record so as to be attached to the image information. Alternatively, the enlargement factor estimation unit 450 may acquire FFD information from imaging conditions stored in a system connected to the network 500 such as the radiation information system (RIS) 210. Alternatively, when measuring the length of the target region, FFD information may be input via the input unit 470 described later.

The site size correction unit 460 corrects the size d ₁ of the image 660 of the target site obtained by the site size calculation unit 420 using the enlargement rate M obtained by the enlargement rate estimation unit 450, and the equation (4). from, to estimate the size _{d 2} of the actual target site 620.

Note that the part size correction unit 460 may output information on the estimated size d ₂ of the actual target part 620 to the image confirmation unit 410. Then, the image checking unit 410, by using the information of the size d ₂ of the magnification M or actual target site 620, appropriately enlarged or reduced size of the template, be displayed superimposed on the X-ray image Good.

  Alternatively, the image confirmation unit 410 may superimpose and display a grid composed of meshes of a predetermined unit (for example, 1 cm / 1 square) on the X-ray image. In this case, the image confirmation unit 410 determines the size of the image of the grid projected on the image receiving surface when the grid is arranged away from the image receiving surface by the same distance as the distance from the image receiving surface to the target part. Using M, the image is enlarged or reduced, and the enlarged or reduced grid is superimposed on the X-ray image. As a result, since the grid arranged at the same position as the target part is superimposed on the X-ray image, the size of the target part can be visually grasped by counting the grids of the grid. it can.

  The input unit 470 includes a keyboard, a mouse, a touch pen, a touch panel, buttons, and the like that receive input of information, and receives information necessary for estimating the size of the target part as necessary. For example, the input unit 470 receives position information of the target part with respect to the body thickness for each patient, and outputs the information to the distance estimation unit 440. The input unit 470 receives information on the height and weight of the patient and outputs the information on the height and weight to the body thickness acquisition unit 430.

  The configuration of the part size estimation device 400 has been described above. Next, the size estimation process of the target part in the part size estimation apparatus 400 will be described with reference to the flowchart of FIG.

The image acquisition unit 411 of the part size estimation apparatus 400 connected to the hospital network accesses the image data server (PACS) 230 and acquires an X-ray image in which the target part of the patient is imaged (step). S710). And the image acquisition part 411 displays the acquired X-ray image on the image reference part 412 of the site | part size estimation apparatus 400 (step S720). Then, the input unit 470, specifies the start point _{d s} and the end point _{d e} of sites (step S730).

Site size calculation unit 420 calculates the reference size d ₀ from the distance from the starting point d _s of the subject region displayed on the screen to the end point d _e, Reference size d _0, the overall size and the image receiving surface of the reference image (IP or The size d ₁ of the image of the target portion on the image receiving surface is calculated from the overall size of the FPD (step S740).

  The body thickness acquisition unit 430 acquires information on the body thickness BT of the patient (step S750).

The distance estimating unit 440, based on the patient's body thickness BT, estimates the distance _{H 1} between the target site receiving surface (step S760).

Then, the enlargement ratio estimation unit 450 estimates the distance H ₁ from the target region to the image receiving surface, which is estimated based on the body thickness BT, and the distance between the focal films that is the distance from the focal point of the X-ray tube to the image receiving surface ( FFD), the enlargement ratio M is estimated (step S770). Note that the enlargement ratio estimation unit 450 acquires information about the distance between the focal films (FFD) from the incidental information of the X-ray image, for example.

The part size correction unit 460 corrects the size d ₁ of the image of the target part obtained by the part size calculation part 420 using the enlargement ratio M obtained by the enlargement ratio estimation part 450, and calculates the actual target part. estimating the size _{d 2} (step S780).

(Oblique shooting)
In the above description, a case has been described in which the patient images the front surface, the back surface, or the side surface of the film (image receiving surface) (front surface image capturing, back surface image capturing, side surface image capturing). By the way, in addition to these directions, there are cases where the patient takes an image with his / her body tilted with respect to the film (an oblique direction image). Oblique direction imaging is often used in imaging the spinal system.

  Therefore, in the following, a case where the present invention is applied to oblique direction shooting will be described. In the following description, it is assumed that the shape of the horizontal cross section of the body is an ellipse.

  FIG. 10A is an example of a horizontal section of the body at the time of front direction photographing, and FIG. 10B is a photograph taken by rotating the front direction by an angle θ (rad) with respect to the film (image receiving surface). It is an example of the horizontal cross section of the body at the time of oblique direction photography. In FIG. 10, the same symbols are attached to the same components as those in FIGS. 6 and 8.

  Here, an ellipse 680-2 in FIG. 10B is in a relationship obtained by rotating the ellipse 680-1 in FIG. 10A by an angle θ (rad) around the origin. 10A and 10B, a is the length (major axis) of the major axis, and b is the length (minor axis) of the minor axis (a> b> 0). .

Therefore, when the ellipse 680-1 in FIG. 10A is expressed by Expression (5), the ellipse 680-2 in FIG. 10B is expressed by Expression (6).

Here, the major axis a is the half of the lateral direction of body thickness BT _L of the body, minor b is the half of the longitudinal direction of body thickness BT _S of the body.

  10A and 10B, a target part 620 indicates a target part at the time of photographing in the front direction, and a target part 620 'indicates a target part at the time of photographing in the oblique direction. The reference line 670 is a line parallel to the film (image receiving surface) 610 and passing through the center of the ellipse. 10A and 10B are displayed so that the centers of the ellipses have the same height.

In FIG. 10B, the target point moving distance h ₀ indicates the difference in distance from the reference line 670 to the target parts 620 and 620 ′ between the front direction photographing and the oblique direction photographing. In FIG. 10B, the body surface moving distance h ₁ indicates the difference in distance from the reference line 670 to the image receiving surface (body surface) 610 when photographing in the front direction and when photographing in the oblique direction.

As can be seen from FIGS. 10A and 10B, the distance H ′ ₁ from the image receiving surface 610 to the target region 620 ′ at the time of photographing in the oblique direction is equal to the target region 620 from the image receiving surface 610 at the time of front direction photographing. than the distance _{H 1} to _become longer by _{h 0 + h 1 (H '} 1 = H 1 + h 0 + h 1).

As described above, the distance estimation unit 440 can calculate the distance H ₁ from the image receiving surface 610 to the target part 620 when photographing in the front direction. Therefore, if the target point movement distance h ₀ and the body surface movement distance h ₁ are known, the distance estimation unit 440 calculates the distance H ′ ₁ from the image receiving surface 610 to the target part 620 ′ at the time of oblique direction imaging. Can do.

Hereinafter, a method of calculating the distance H ′ ₁ from the image receiving surface 610 to the target portion 620 ′ at the time of photographing in the oblique direction will be described.

(Target point travel distance)
When the coordinates of the target part 620 before rotation are (X, Y) and the coordinates of the target part 620 ′ after θ rotation are (X ′, Y ′), the target point moving distance h ₀ is calculated as follows. The

Here, the following relationship exists between the coordinates (X, Y) of the target part 620 before rotation and the coordinates (X ′, Y ′) of the target part 620 ′ after θ rotation.

Therefore, if the coordinates (X, Y) and the angle θ of the target part 620 before rotation are known, the target point moving distance h ₀ can be calculated.

  For the coordinates (X, Y) of the target part 620 before rotation, the distance estimation unit 440 includes a horizontal section of the body and position information indicating the position of each part in a predetermined coordinate system with the center of the body as the origin. It is made to have a position information table matched and it acquires from the position information table concerned. FIG. 11 is a diagram illustrating an example of the position information table.

  As shown in FIG. 11, each part, body position, direction, angle θ, and position information (Rx, Ry) are associated with each other in the position information table. Here, the angle θ represents how much the horizontal direction of the body at the time of photographing is rotated from the X axis of a predetermined coordinate system. The position information (Rx, Ry) represents the position of each part in a predetermined coordinate system as a ratio to the major axis and the minor axis. The predetermined coordinate system has, for example, the center of the body as the origin, the left-right direction of the body as the X axis, the vertical direction of the body as the Y axis, the right direction of the body as the positive direction of the X axis, and the front direction of the body as Y. The coordinate system is the positive direction of the axis. In this case, the angle θ represents how much the body has rotated from the front direction, and the position information (Rx, Ry) has the origin at the center of the body, the left-right direction of the body is the X axis, and the vertical direction of the body is The position of each part in the coordinate system in which the Y axis is the right direction of the body is the positive direction of the X axis and the front direction of the body is the positive direction of the Y axis is expressed as a ratio to the major axis and the minor axis.

  In addition, since the position information (Rx, Ry) of each part differs between the standing position and the recumbent position, the position information (Rx, Ry) for each combination of the part and the body position is shown in the position information table shown in FIG. ) Are associated.

  Further, the position information table shown in FIG. 11 includes information on the shooting direction and the angle θ. This is because, for example, when the photographing direction is RAO (Right Anterior Oblique Position) or LAO (Left Anterior Oblique Position), the optimum angle θ for photographing may differ depending on the photographing part. For example, even if the imaging direction is RAO, the angle θ is 40 degrees when the imaging site is the lumbar spine, whereas the angle θ is 45 degrees when the imaging site is the cervical spine.

  In addition to the position information table, the distance estimation unit 440 includes the information on the angle θ in addition to the information on the imaging region, the body position at the time of imaging, and the imaging direction in the incidental information of the X-ray image. Information on the angle θ may be acquired from the incidental information of the X-ray image. In this case, the position information table stores at least one association between each part, body position, and position information indicating the position of each part in a predetermined coordinate system with the center of the body as the origin. Therefore, the capacity of the position information table can be reduced.

Using the position information (Rx, Ry), the coordinates (X, Y) of the target part 620 before rotation, that is, when photographing in the front direction, are calculated as follows.

By substituting the information of Expression (9) and the angle θ into Expression (7) and Expression (8), the target point movement distance h ₀ can be calculated.

In this way, the distance estimation unit 440 has a position information table in which position information indicating the position of each part in a predetermined coordinate system having the origin at the center of the body is associated with the position information. The position information associated with the target part is acquired from the table, and the target point moving distance h ₀ is calculated based on the body thickness, the position information, and the imaging direction.

(Body surface travel distance)
From FIG. 10 (A) and FIG. 10 (B), the body surface moving distance h ₁ is assumed that the shape of the horizontal cross section of the body is an ellipse (a>b> 0) having a major axis a and a minor axis b. If, from the absolute value of the extremum Y _L of formula (6), seen as the distance obtained by subtracting the short diameter b.

The absolute value | Y _L | of the extreme value Y _L is calculated as follows by differentiating the equation (6) of the ellipse 680-2 in FIG.

Here, c is expressed as follows.

In this way, the distance estimation unit 440 calculates the distance H ′ ₁ from the image receiving surface 610 to the target part 620 ′ at the time of photographing in the oblique direction, from the target point moving distance h ₀ and the body surface moving distance h _1. can do. Then, the enlargement factor estimation unit 450 estimates the enlargement factor M at the time of photographing in the oblique direction using the distance H ′ ₁ instead of the distance H ₁ in the equation (3).

The left-right direction of the body at the time of photographing in the front direction is the X axis, the vertical direction of the body is the Y axis, the right direction of the body is the positive direction of the X axis, and the front direction of the body is the positive direction of the Y axis With respect to the system, the rear direction shooting and the side direction shooting have a relationship of θ = 180 (°) and θ = 90 (°), respectively. Therefore, even if the rear direction shooting and lateral imaging, as in the case of oblique direction shooting, the body thickness and BT _L and BT _S, the target point moves distance h ₀ and body movement distance h ₁ Tokyo, image receiving surface The distance between the target part and the target part can be calculated.

  Therefore, in the position information table in this case, the above-described position reference information becomes unnecessary, and if at least one position information (Rx, Ry) is stored for each combination of body part and body position, it is possible to display in all imaging directions. On the other hand, the distance between the image receiving surface and the target part can be calculated, and the capacity of the position information table can be suppressed. Further, when the body thickness is calculated using the formula (2), the body thickness correction coefficient table only needs to store the body thickness correction coefficient in the front-rear direction of the body in the predetermined coordinate system. The capacity of the correction coefficient table can be suppressed.

(Correction of magnification)
In the above description, the case where the target part is on the center line of the X-ray has been described. However, the target part is not necessarily on the center line of the X-rays in all imaging. In addition, for convenience of imaging, there is a case where the target region is intentionally removed from the X-ray center line. When the target part is off the center line of the X-ray, the distance between the focal point of the X-ray and the target part becomes longer than when the target part is on the center line of the X-ray.

  Therefore, in the following, a method for estimating the actual size of the target portion with higher accuracy when the target portion is off the center line of the X-ray will be described. The center line of the X-ray is perpendicular to the film (image receiving surface), and the point where the X-ray center line and the film (image receiving surface) intersect is called the film center.

  FIG. 12A is a view of the positional relationship between the focal point of the X-ray tube and the target part as viewed from directly above the focal point of the X-ray tube. FIG. 12B shows a cross section passing through II of FIG. 12A and perpendicular to the image receiving surface. Note that in FIGS. 12A and 12B, the same reference numerals are given to the same components as those in FIGS. 12A and 12B, a target site 620 indicates a target site located on the center line of the X-ray, and a target site 620 ′ indicates a target site positioned off the center line of the X-ray. Show.

In FIG. 12 (A), _{d 3} is the distance between the center line of the X-ray and the target site 620 '. In FIG. 12B, H ′ ₃ is the distance between the focal point 600 of the X-ray tube and the target portion 620 ′, and H ′ ₁ is between the target portion 620 ′ and the image receiving surface 610. Is the distance.

As can be seen from FIG. 12B, H ′ ₃ and H ′ ₁ can be calculated as follows.

Further, the focal film distance FFD ′ when the target part is deviated from the center line of the X-ray is as follows.

Therefore, when the target part is off the center line of the X-ray, the enlargement ratio estimation unit 450 estimates the enlargement ratio M from the focal film distance FFD ′ and the distance H ′ ₃ using the equation (16). To do.

Specifically, when the target part is off the center line of the X-ray, the part size calculation unit 420 calculates the distance d ″ ₃ between the center of the image of the target part displayed on the image reference unit 412 and the film center. For example, the part size calculation unit 420 specifies the center of the image of the target part and the center of the film using, for example, the input unit 470 (keyboard, mouse, touch pen, touch panel, button, etc.). The method for acquiring information about the center of the image of the target region and the center of the film is not particularly limited.

Then, the site size calculation unit 420 calculates the distance d ′ ₃ between the center of the image of the target site on the image receiving surface and the center of the film using the following relational expression.
d ′ ₃ = d ″ ₃ × R

  Here, as described above, the ratio R is the ratio of the overall size of the image receiving surface (such as IP or FPD) to the overall size of the reference image, that is, R = the overall size of the image receiving surface / the overall size of the reference image. .

  In step S770, the enlargement rate estimation unit 450 estimates the enlargement rate using equation (16) instead of equation (3).

  Thereby, even when the target part is photographed with a deviation from the center of the film, the actual size of the target part can be estimated with higher accuracy.

  As described above, in the part size estimation apparatus 400 according to the embodiment of the present invention, the distance estimation unit 440 estimates the distance between the target part and the image receiving surface based on the body thickness of the patient. Then, the enlargement ratio estimation unit 450 calculates the target portion projected on the image receiving surface based on the distance between the target portion and the image receiving surface and the distance between the focal point of the X-ray tube and the image receiving surface. Estimate the enlargement factor required to correct the image size. Then, the site size correction unit 460 corrects the size of the image of the target site projected on the image receiving surface using this enlargement factor, and estimates the actual size of the target site.

  In this manner, the distance estimation unit 440 determines whether the distance between the target part and the image receiving surface is based on the body thickness used for adjusting the X-ray dose and the position information of the target part with respect to the body thickness. The distance is estimated, and the magnification rate estimation unit 450 estimates the magnification rate based on the distance between the target region and the image receiving surface and the distance between the focal point of the X-ray tube and the image receiving surface. Thereby, in the part size estimation apparatus 400, since the enlargement ratio is estimated based on the body thickness of the patient without using the metal sphere as a marker, the metal sphere is arranged according to the target part, Compared with the method of photographing a metal ball at the same time and estimating the enlargement ratio, it is possible to save time and effort at the time of photographing. Moreover, in the site | part size estimation apparatus 400, since the expansion rate according to a patient's body shape is set based on a patient's body thickness, the size of an object site | part can be estimated with a higher precision.

  Further, the distance estimation unit 440 has a position information table in which each part is associated with position information indicating the position of each part in a predetermined coordinate system with the center of the body as the origin. Position information associated with the part is acquired, and a distance between the target part and the image receiving surface is estimated based on the body thickness, the position information, and the imaging direction.

  In addition, the body thickness acquisition unit 430 estimates the body thickness based on the patient's height, weight, target region, photographing body position, and photographing direction. In this case, the body thickness acquisition unit 430 holds a body thickness correction coefficient table in which the part, body position, body thickness direction, and body thickness correction coefficient f are associated with each other, and information on the height and weight of the patient is stored. If it can be obtained, the body thickness can be estimated without placing a metal sphere and measuring the body thickness, so the size of the target site should be estimated using an appropriate magnification for each patient. Can do.

  When the body thickness acquisition unit 430 estimates the body thickness based on the patient's height, weight, and body thickness correction coefficient according to the target site, body position, and imaging direction, the body thickness acquisition unit 430 The body thickness can be estimated using information included in the incidental information of the X-ray image. In this case, the body thickness acquisition unit 430 can estimate the body thickness by using the incidental information of the X-ray image, and thus can suppress an increase in cost for calculating the body thickness.

  Further, the distance estimation unit 440 estimates the distance between the target part and the image receiving surface according to the position information of the target part with respect to the body thickness. Thereby, since an expansion rate can be estimated according to a patient's body thickness, ie, a patient's body shape, the size of an object part can be estimated with higher accuracy.

  Further, the input unit 470 receives position information of the target part with respect to the body thickness, and information on the height and weight of the patient. As a result, the enlargement rate estimation unit 450 can estimate the enlargement rate by designating the position of the target part with respect to the body thickness of the patient using the results of the examination that the patient has received in the past. The size of the part can be estimated with higher accuracy. Even when the height and weight information of the patient is not added to the incidental information of the X-ray image, the body thickness acquisition unit 430 can estimate the body thickness.

  In any case of the body thickness acquisition method in the body thickness acquisition unit 430, the metal sphere is arranged in such a way that the enlargement ratio is set by arranging the metal sphere so that the distance from the image receiving surface is the same as the target site. In the method of estimating the enlargement ratio based on the enlargement ratio, the enlargement ratio can be estimated with higher accuracy without troublesome work. Furthermore, in the present invention, since the body thickness used for adjusting the dose in X-ray imaging is used for estimating the enlargement ratio, an appropriate enlargement ratio is estimated while suppressing an increase in cost and the like. Can do.

  In addition, in the method of setting the enlargement ratio using a metal sphere, if an image is taken without arranging the metal sphere, the image must be taken again with the metal sphere arranged, and the exposure dose of the patient is reduced. In contrast, the present invention does not require a metal sphere, so that an increase in patient exposure can be suppressed.

  In the above description, the case where the focus size of the X-ray light source is small has been described as an example. However, the present invention can be applied even when the focus size is large.

  In the above description, the case where the part size estimation apparatus 400 acquires a digitized X-ray image via the network 500 in the hospital has been described as an example. However, the network environment is not maintained in the hospital. Even in this case, the present invention can be applied. In this case, the film output using the developing machine may be considered as the X-ray image (reference image) displayed on the image reference unit 412 described above. Then, the ratio R may be calculated from the overall size of the film (reference image) and the size of the image receiving surface during X-ray imaging. In this case, the reference size is the size of the image of the target portion displayed on the film (reference image).

  Then, the size of the actual target portion may be calculated using the ratio R and the enlargement ratio M, as in the case of the digitized X-ray image. Alternatively, using the ratio R and the enlargement ratio M, the template of the artificial joint may be enlarged or reduced, and the template after enlargement or reduction may be superimposed on the film to select the optimum template. .

  As described above, the present invention is not limited to a digitized X-ray image, and can be applied to a case where the target portion can be confirmed only with a film.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

  FIG. 13 shows an implementation example of a computing device suitable for realizing the part size estimation apparatus 400 according to the embodiment of the present invention.

  A computing device 800 in FIG. 13 includes a central processing unit (CPU) 810, a memory 820, and a recording medium 830, which are coupled via a bus.

  The CPU 810 operates together with an operating system (not shown) to execute program code read into a memory 820 such as a RAM (Random Access Memory). The program code and data can be recorded in advance in a recording medium 830 such as a ROM (Read Only Memory) or a hard disk. Alternatively, the program code and data are removable recording such as a magnetic disk such as a floppy (registered trademark) disk, an optical disk such as a CD (Compact Disc) and a DVD (Digital Versatile Disc), and a magneto-optical disk such as an MO (Magneto Optical) disk. It is possible to store (record) the medium 840 temporarily or permanently. Such a removable recording medium 840 can be provided as so-called package software.

  In addition to installing the program code and data from the removable recording medium 840 as described above to the computing device 800, the program code and data are installed from the download site via wired or wireless transfer via the network I / F 850, and the computing device 800 Alternatively, the transferred program or data may be received and installed in the built-in recording medium 830.

  Further, a mass storage device 860 such as a hard disk, CD-ROM, magneto-optical (floppy) drive, or tape drive may be coupled to the CPU 810. The mass storage device 860 stores additional program codes and data. Further, the address space of the mass storage device 860 may be accessible by the CPU 810 for virtual memory, for example. Further, instead of the recording medium 830, the mass storage device 860 may store the corresponding program and data.

  Each of the computing devices 800 described above further includes an input device 870 such as a keyboard and a pointer device (for example, a mouse or a touch pen). The computing device 800 includes a display device 880 for viewing images and the like.

  When operating under the control of appropriate software or firmware, the CPU 810 is responsible for implementing certain functions associated with the functions of the desired computing device 800. For example, when the region size estimation apparatus 400 is realized by the computing device 800, the functions of the region size calculation unit 420, the body thickness acquisition unit 430, the distance estimation unit 440, the enlargement rate estimation unit 450, and the region size correction unit 460 are performed by the CPU 810. It is realized by. The body thickness correction coefficient table and the position information table are stored in the recording medium 830, the removable recording medium 840, the mass storage device 860, and the like. The functions of the image confirmation unit 410 and the input unit 470 are realized by the display device 880, the input device 870, and the like.

  In addition to being executed in time series in accordance with the processing operations described in the above embodiment, the processing capability of the apparatus that executes the processing, or to be executed in parallel or individually as necessary Is also possible.

  Moreover, the part size assumption apparatus demonstrated by the said embodiment can also be constructed | assembled so that it may become a logical set structure of a some apparatus, or the function of each apparatus may be mixed.

100 Hospital Information System (HIS)
200 Radiation Division System 210 Radiation Information System (RIS)
220 Modality 230 Image Data Server (PACS)
DESCRIPTION OF SYMBOLS 300 Terminal 400 Part size estimation apparatus 410 Image confirmation part 411 Image acquisition part 412 Image reference part 420 Part size calculation part 430 Body thickness acquisition part 440 Distance estimation part 450 Magnification rate estimation part 460 Part size correction | amendment part 470 Input part 500 Network 800 Computer Device 810 CPU
820 Memory 830 Recording medium 840 Removable recording medium 850 Network I / F
860 Mass storage device 870 Input device 880 Display device

Claims (13)

In X-ray imaging, an estimation device for estimating an enlargement ratio necessary for correcting the size of an image of a bone or joint of a patient projected on an image receiving surface,
Distance estimating means for estimating a distance between the bone or joint and the image receiving surface based on the body thickness of the patient and the position information of the bone or joint relative to the body thickness;
An enlargement factor estimating means for estimating the enlargement factor based on a distance between the bone or joint and the image receiving surface and a distance between a focal point of an X-ray tube and the image receiving surface; ,
Estimating device. The distance estimating means includes
And the bone or joint, has a position information table in which the position information of the bone or joint associated to said body thickness, obtains the position information associated with the bone or joint from the position information table, Based on the body thickness and the position information, estimate a distance between the bone or joint and the image receiving surface,
The estimation apparatus according to claim 1. The distance estimating means includes
And the bone or joint, has a position information table in which the position information indicating the position of the bone or joint associated in a predetermined coordinate system with its origin at the center of the body, to the bone or joint from the position information table Obtaining the associated position information, and estimating the distance between the bone or joint and the image receiving surface based on the body thickness, the position information, and the imaging direction;
The estimation apparatus according to claim 1. An input means for receiving position information of the bone or joint with respect to the body thickness;
The distance estimating means estimates a distance between the bone or joint and the image receiving surface based on the body thickness and the input position information.
The estimation apparatus according to claim 1. Further comprising body thickness obtaining means for obtaining information on the body thickness of the patient,
The estimation apparatus according to any one of claims 1 to 4. The body thickness acquisition means includes
Bone or joint, the posture, the direction of body thickness to hold the body thickness correction coefficient table body thickness correction coefficient and (f) are associated, from the body thickness correction coefficient table, the bone or joint, shooting The body thickness correction coefficient (f) is acquired according to the body position and the photographing direction at the time, the patient's height (H), the patient's weight (W), and the acquired body thickness correction coefficient From (f) and equation (1), the body thickness (BT) is estimated.
The estimation apparatus according to claim 5.

Here, α and β are constants. The body thickness acquisition means includes
From the incidental information of the X-ray image, obtain information on the height and weight of the patient,
The estimation apparatus according to claim 6. An input means for receiving information on the height and weight of the patient;
The estimation apparatus according to claim 6. Size correction means for correcting the size of the image of the bone or joint projected on the image-receiving surface using the enlargement ratio and estimating the actual size of the bone or joint is further provided.
The estimation apparatus according to claim 7 or 8. In X-ray imaging, an estimation method for estimating an enlargement ratio necessary for correcting a size of an image of a bone or joint of a patient projected on an image receiving surface,
Based on the body thickness of the patient and the position information of the bone or joint relative to the body thickness, the distance between the bone or joint and the image receiving surface is estimated,
Estimating the magnification based on the distance between the bone or joint and the image receiving surface and the distance between the focal point of the X-ray tube and the image receiving surface;
Estimation method. In X-ray imaging, an estimation device that estimates an enlargement ratio that is necessary when correcting the size of an image of a bone or joint of a patient projected on an image receiving surface,
Distance estimating means for estimating a distance between the bone or joint and the image receiving surface based on the body thickness of the patient and the position information of the bone or joint relative to the body thickness;
Based on the distance between the bone or joint and the image receiving surface, and the distance between the focal point of the X-ray tube and the image receiving surface, function as an enlargement rate estimating means for estimating the enlargement rate,
program. Estimating the distance between the bone or joint and the image receiving surface is
And the bone or joint, the body and the position information of the bone or joint obtains the position information associated with the bone or joint from the position information table associated to the thickness, the body thickness and the position information Based on estimating a distance between the bone or joint and the image receiving surface;
The estimation method according to claim 10. The distance estimating means includes
And the bone or joint, has a position information table in which the position information of the bone or joint associated to said body thickness, obtains the position information associated with the bone or joint from the position information table, Based on the body thickness and the position information, estimate a distance between the bone or joint and the image receiving surface,
The program according to claim 11.

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