JP2018183364A - Radiographic imaging apparatus, radiographic imaging method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic imaging technology capable of suppressing deterioration of resolution of a radiation image with a higher degree of precision.SOLUTION: A radiographic imaging device includes a radiation generation part for generating radiation, a radiation detection part for detecting radiation irradiated from the radiation generation part, and a rotation part for rotating the radiation generation part and the radiation detection part in a state in which they are opposed to each other. The radiographic imaging device includes a position detection part for detecting the positions of the radiation generation part and the radiation detection part, and an arithmetic part for generating a radiation image reconfiguring a three-dimensional information on a subject based on a signal output from the radiation detection part. The arithmetic part generates the radiation image by correcting the signal output from the radiation detection part using the position information on the radiation generation part and the radiation detection part detected by the position detection part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation imaging apparatus, a radiation imaging method, and a program.

  As a radiation imaging apparatus, there is a CT apparatus that images a subject by rotating a radiation generation unit that generates radiation and a radiation detection unit that detects radiation by a rotation unit. In the CT apparatus, the radiation generation unit and the radiation detection are arranged to face each other with a rotation axis passing through an opening through which the subject is inserted, and are configured to rotate around the rotation axis.

  In the CT apparatus, there may be a case where the radiation generating unit and the radiation detector are deviated from the designed rotation trajectory due to deflection or vibration of the radiation generating unit and the member holding the radiation detector while taking a projected image. When a projection image is backprojected to reconstruct a CT image, the resolution of the reconstructed CT image can be reduced unless the deviation from the designed trajectory is corrected in advance.

  As an apparatus configuration for suppressing such a decrease in the resolution of a CT image, for example, in Patent Document 1, a vibration detection unit is used during projection image capturing to detect vibration and position of a radiation detector in real time. An apparatus configuration for converting a projected image using the above is disclosed.

JP 2002-291726 A

  However, in the apparatus configuration disclosed in Patent Document 1, misalignment of the radiation detector is taken into consideration, but misalignment of the radiation generating unit is not taken into consideration. For this reason, when not only the positional deviation of the radiation detector but also the positional deviation of the radiation generating part occurs during the projection image capturing, the configuration of Patent Document 1 uses the resolution of the CT image caused by the positional deviation of the radiation generating part. Can not be suppressed.

  Therefore, an object of the present invention is to provide a radiographic technique capable of suppressing a decrease in resolution of a radiographic image with higher accuracy.

A radiation imaging apparatus according to an aspect of the present invention includes a radiation generation unit that generates radiation, a radiation detection unit that detects radiation emitted from the radiation generation unit, and the radiation generation unit and the radiation detection unit that face each other. A radiation imaging apparatus having a rotating unit that rotates in a state where the radiation is generated, and a position detection unit that detects a position of the radiation generation unit and the radiation detection unit;
A calculation unit that generates a radiographic image obtained by reconstructing three-dimensional information of a subject based on a signal output from the radiation detection unit;
The calculation unit corrects a signal output from the radiation detection unit using the radiation generation unit detected by the position detection unit and position information of the radiation detection unit, and generates the radiation image. Features.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the radiography technique which can suppress the fall of the resolution of a radiographic image with higher precision.

The figure which shows the structural example of the radiography apparatus which concerns on 1st Embodiment of this invention. The figure explaining the imaging process by the radiography apparatus which concerns on 1st Embodiment. The figure which shows the flow of the arithmetic processing by the radiography apparatus which concerns on 1st Embodiment. FIG. 4 is a diagram for explaining a method for correcting image misregistration according to the first embodiment. The figure explaining the prior data acquisition process by the radiography apparatus which concerns on 2nd Embodiment. The figure explaining the production | generation of the correction parameter of the rotation radius which concerns on 2nd Embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the constituent elements described in the embodiments are merely examples, and the technical scope of the present invention is determined by the claims, and is not limited by the following individual embodiments. . In this specification, the radiation is not limited to X-rays, and may be electromagnetic waves, α rays, β rays, γ rays, or the like.

<First Embodiment>
In the first embodiment, a configuration of a CT apparatus that captures a radiographic image of a subject using an X-ray that is a kind of radiation will be described as a radiographic apparatus. FIG. 1 shows an example of the overall configuration of a radiation imaging apparatus 100 in the first embodiment. Hereinafter, the configuration of the radiation imaging apparatus 100 of the first embodiment will be described with reference to FIG.

  In FIG. 1, the radiation irradiation unit 101 irradiates a subject P with radiation based on the control of the control unit 104. The radiation irradiation unit 101 includes a radiation generation unit (tube or radiation tube) that generates radiation and a collimator that defines a beam divergence angle of the radiation generated in the radiation generation unit. The radiation detection unit 102 detects the radiation emitted from the radiation generation unit. The radiation detection unit 102 is, for example, an FPD (flat panel detector), has an image sensor distributed in two dimensions, detects a two-dimensional distribution of radiation that has reached the radiation detection unit 102, and generates radiation image data. . The radiation detection unit 102 transmits the generated radiation image data to the calculation unit 105.

  The imaging condition setting unit 103 includes an imaging condition input unit that allows an operator to input imaging condition information such as a target dose of radiation irradiated to the subject P and a tube voltage. Set conditions. The shooting condition setting unit 103 transmits the shooting condition information input by the operator to the control unit 104. The control unit 104 controls the radiation irradiation unit 101, the radiation detection unit 102, and the rotation unit 108 based on a signal (imaging condition information) from the imaging condition setting unit 103. The rotation unit 108 includes a radiation irradiation unit 101, a radiation detection unit 102, and a position detection unit 107. The rotation unit 108 is based on a signal from the control unit 104, and the radiation irradiation unit 101 (radiation generation unit). And the radiation detection unit 102 are opposed to each other and rotated around the subject P.

  The radiation irradiation unit 101 (radiation generation unit) and the radiation detection unit 102 are arranged facing each other, and the position detection unit 107 includes a radiation irradiation unit 101 (radiation generation unit) and a radiation detection unit that are rotated by a rotation unit 108. The position information 102 is detected, and the detected position information is transmitted to the calculation unit 105.

  The calculation unit 105 reconstructs a CT image (CT image data) based on the radiation image data transmitted from the radiation detection unit 102 and the position information transmitted from the position detection unit 107. Based on the signal output from the radiation detection unit 102, the calculation unit 105 generates a radiation image in which the three-dimensional information of the subject P is reconstructed. When generating the radiation image, the calculation unit 105 corrects the signal output from the radiation detection unit 102 using the position information of the radiation generation unit and the radiation detection unit 102 detected by the position detection unit 107. Then, a radiation image (CT image data) is generated. The calculation unit 105 transmits the reconstructed CT image data to the image storage unit 109. The image storage unit 109 stores the received CT image data in a storage area. Then, the CT image data is transmitted to the image display unit 106. The image display unit 106 outputs the received radiation image data (CT image data) to the display unit 110 such as a monitor. The image display unit 106 performs display control for displaying the generated radiation image data (CT image data) on the display unit 110.

  Next, processing from the start to the end of shooting of a subject according to the first embodiment will be described with reference to FIGS. 2, 3, and 4. In the first embodiment, when the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102 deviate from the designed rotation radius, a deviation from the design value of the rotation radius is measured in real time at the time of photographing an object, and the information is used. A configuration that corrects a signal output from the radiation detection unit 102 and suppresses a decrease in resolution will be described.

  In step S201, the imaging condition setting unit 103 accepts input of imaging conditions (for example, tube voltage kV, tube current mA, number of images taken for one round of shooting imax, etc.) by an operator's operation input via the imaging condition input unit. The shooting condition setting unit 103 transmits the input shooting conditions to the control unit 104.

  In step S <b> 202, the control unit 104 controls the rotation unit 108 based on the imaging condition information received from the imaging condition setting unit 103, and each radiographic image (image Ii) obtained by imaging the subject P is photographed once around the subject. The rotating unit 108 is rotated so that images are taken at angular increments divided by the number imax.

  In step S203, the control unit 104 sets an initial value 0 to the number index i as the number information of the radiation image. In step S204, the control unit 104 controls the radiation detection unit 102 to start acquiring a radiographic image (image Ii) of the subject.

  In step S205, the control unit 104 controls the radiation irradiation unit 101 to irradiate the subject P with radiation based on the imaging conditions (tube voltage kV, tube current mA) input in step S201.

  In step S <b> 206, the position detection unit 107 acquires position information of the radiation irradiation unit 101 and the radiation detection unit 102, and as the acquired position information, radius information Rgi of the focal point of the tube of the radiation irradiation unit 101 and the radiation detection unit 102. The radius information Rfi of the radiation detection position is transmitted to the calculation unit 105.

  In step S207, the control unit 104 controls the radiation irradiation unit 101, and the radiation irradiation unit 101 stops the radiation irradiation. In step S <b> 208, the control unit 104 controls the radiation detection unit 102 and ends the acquisition of the captured radiographic image (image Ii) of the subject.

  In step S <b> 209, the radiation detection unit 102 transmits a radiation image (image Ii) of the subject to the calculation unit 105. In step S210, the control unit 104 adds 1 to the number information (number index i) of the captured radiographic image, and counts up the number information (number index i).

  In step S211, the control unit 104 compares the number index i with the one-shot photographed number imax. If the number index i is less than the one-shot photographed number imax (S211—Yes), the process returns to step S204, and from step S204 to step S210. The above process is repeated in the same manner. On the other hand, if it is determined in step S211 that the number index i is greater than or equal to the one-shot photograph number imax (S211-No), the process proceeds to step S212.

  In step S212, the control unit 104 controls the rotating unit 108 to stop the rotation of the rotating unit 108. In step S213, the calculation unit 105 based on the received radius information Rgi of the focal point of the tube of the radiation irradiation unit 101, the radius information Rfi of the radiation detection position of the radiation detection unit 102, and the radiation image (image Ii) of the subject. , CT image data is generated. Details of the processing in step S213 will be described with reference to FIGS.

  As a specific calculation process in step S213, the calculation unit 105 performs the process of the flowchart shown in FIG. First, in step S301, the calculation unit 105 calculates the second radiation sensitivity for the acquired radiation image (image Ii) of the subject based on the two-dimensional distribution information of the radiation sensitivity of the imaging element of the radiation detection unit 102 acquired in advance. Perform correction (sensitivity correction) to make the dimensional distribution uniform.

  Next, in step S <b> 302, the calculation unit 105 detects the positional deviation of the image caused by the displacement from the design values of the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102 with respect to the radiation image (image Ii) after sensitivity correction. Perform correction (position correction). A specific method of position correction will be described with reference to FIG.

  In FIG. 4, Rg is a design value of the radius of the focal point of the tube of the radiation irradiation unit 101, and Rf is a design value of the radius of the radiation detection position of the radiation detection unit 102. Rgi is the radius of the focal point of the tube of the radiation irradiation unit 101 at the time when the radiation image (image Ii) of the number index i is acquired. Rfi is the radius of the radiation detection position of the radiation detection unit 102 at the time when the radiation image (image Ii) of the number index i is acquired. Xi is an arbitrary distance from the radiation irradiation axis in the radiation image (image Ii).

  The rotation unit 108 rotates the radiation irradiation unit 101 (radiation generation unit) and the radiation detection unit 102 around the rotation center O, and the position detection unit 107 performs the radiation irradiation unit 101 (radiation generation unit) with respect to the rotation center O. And the position of the radiation detector 102 are detected.

  In step S <b> 302, the calculation unit 105 detects the rotation radius Rg of the radiation generation unit and the rotation radius Rf of the radiation detection unit 102, which are set in advance with respect to the rotation center O, and the position detection unit 107 when photographing the subject P. The signal output from the radiation detection unit 102 is corrected based on the positions (the positions of the radiation generation unit and the radiation detection unit 102).

  That is, as a correction of the signal output from the radiation detection unit 102, the calculation unit 105 shows the pixel values of all the imaging elements of the radiation detection unit 102 for the radiation image (image Ii) after the sensitivity correction, as shown in FIG. In this way, position correction (position conversion) is performed by replacing the pixel value of the image sensor at the position of the distance Xi with the position of the distance X shown in the equation (1), and a radiation image of the subject after position correction is generated.

(Rg + Rf) * Rgi * Xi / (Rg * (Rgi + Rfi)) (1)
By this position correction, it is possible to suppress image misalignment caused by displacement from the design values of the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102.

  In step S303, the calculation unit 105 applies a reconstruction filter to the radiation image (image Ii) after position correction (reconstruction filter processing). In step S304, the calculation unit 105 projects the radiographic image (image Ii) after the reconstruction filter processing in a direction opposite to the radiation irradiation direction. The computing unit 105 generates a radiographic image (CT image information) in which the three-dimensional information of the subject is reconstructed by back projecting the radiographic image (image Ii) after the reconstruction filter processing on the total number index i. In step S <b> 305, the calculation unit 105 transmits the generated radiation image (CT image information) to the image storage unit 109. Thus, the calculation process in step S213 is completed.

  Returning to FIG. 2, in step S <b> 214, the image storage unit 109 stores the radiation image (CT image information) received from the calculation unit 105 in the storage area. Then, the image storage unit 109 transmits the received radiation image (CT image information) to the image display unit 106. Next, in step S <b> 215, the image display unit 106 displays the received radiation image (CT image information) on the display unit 110. Thus, the subject photographing process is completed.

  By the processing described above, it is possible to suppress a reduction in the resolution of the radiation image that occurs when the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102 deviate from the designed radius. Thereby, compared with the structure currently disclosed by patent document 1, the radiography technique which can suppress the resolution fall of a radiographic image with higher precision can be provided. In the first embodiment, the CT apparatus in which the radiation irradiation unit 101 and the radiation detection unit 102 rotate around the subject has been described. However, the embodiment of the present invention can also be applied to a tomosynthesis imaging apparatus. In the first embodiment, when generating a radiographic image, the filter-corrected back projection method is used as shown in steps S303 and S304, but a successive approximation reconstruction method may be used.

  According to the present embodiment, it is possible to provide a radiographic technique that can suppress a decrease in resolution of a radiographic image with higher accuracy.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In this embodiment, the deviation from the design values of the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102 is determined by using the trajectory information of the radiation irradiation unit 101 (radiation generation unit) and the radiation detection unit 102 measured in advance. A configuration for suppressing a decrease in resolution by correcting a signal output from the detection unit 102 will be described. In the first embodiment, deviations from the design values of the rotation radii of the radiation irradiating unit 101 and the radiation detecting unit 102 are measured in real time when the subject is photographed, and the information output from the radiation detecting unit is corrected using the information. Reduced resolution. On the other hand, in the second embodiment, the signal output from the radiation detection unit 102 is corrected using the trajectory information of the radiation irradiation unit 101 and the radiation detection unit 102 measured in advance. It differs from the form. The position detection unit 107 is configured to be detachable from the radiation imaging apparatus 100, and is also the first in that it detects the positions of the radiation generation unit and the radiation detection unit while being attached to the radiation imaging apparatus 100. This is different from the embodiment.

  Below, in order to avoid duplication of description, the part which is different from 1st Embodiment is demonstrated. In the second embodiment, for example, a decrease in resolution due to deviation from the design values of the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102 caused by gravity and environmental temperature changes of the radiation imaging apparatus 100 is suppressed. In the second embodiment, the trajectory information of the radiation irradiation unit 101 (radiation generation unit) and the radiation detection unit 102 is acquired before the imaging processing by the radiation imaging apparatus 100 described in FIG. And the approximate expression which shows the deviation | shift amount from the design value of the rotation radius of the radiation irradiation part 101 and the radiation detection part 102 is produced | generated. The prior data acquisition process before the start of imaging according to the second embodiment will be described below with reference to FIG.

  In step S <b> 501, the imaging condition setting unit 103 captures the subject in the imaging environment in which the radiation imaging apparatus 100 is installed based on the information about the number of images taken for one round imax and the radiography apparatus 100 based on the operation input by the operator via the imaging condition input unit. Information on at least one environmental temperature or information on a plurality of environmental temperatures assumed at times is set. The input information is transmitted to the control unit 104.

  In step S502, in an environment where the radiation imaging apparatus 100 is installed, the operator operates an environmental temperature setting unit (not shown) to set the environmental temperature of the radiation imaging apparatus 100 to the environmental temperature input in step S501. When information on a plurality of environmental temperatures is input in step S501, for example, the lowest temperature among the environmental temperatures input by the operator is set.

  In step S503, the control unit 104 controls the rotation unit 108 based on the information received from the imaging condition setting unit 103, and performs radiographic image (image Ii) when imaging the subject P as in step S202. ) Rotates the rotating unit 108 so that the image is photographed in angular increments obtained by dividing the circumference of the subject (360 degrees) by the number of images taken for one revolution imax.

  In step S504, the control unit 104 sets an initial value 0 to the number index i as the number information of radiographic images. In step S505, the position detection unit 107 acquires the position information of the radiation irradiation unit 101 and the radiation detection unit 102. As the acquired position information, the tube of the radiation irradiation unit 101 at the position of the number index i at the time of subject shooting. The radius information Rgi of the focal point of the sphere and the radius information Rfi of the radiation detection position of the radiation detection unit 102 are transmitted to the calculation unit 105.

  In step S506, the control unit 104 adds 1 to the sheet number index i and counts up the sheet number index i. In step S507, the control unit 104 compares the number index i with the one-shot photograph number imax, and if the number index i is less than the one-shot photograph number imax (S507-Yes), the process returns to step S505, and steps S505 to S506 are performed. The above process is repeated in the same manner. On the other hand, if it is determined in step S507 that the number index i is greater than or equal to the one-shot photograph number imax (S507-No), the process proceeds to step S508.

  In step S508, the control unit 104 controls the rotation unit 108 to stop the rotation of the rotation unit 108. Next, in step S509, when the temperature setting is changed by the operation of the environmental temperature setting unit (not shown) by the operator (S509-Yes), the process returns to step S503, and the processes from step S503 to step S508 are performed. Repeat in the same way. For example, when information on a plurality of environmental temperatures is input in step S501, for example, a temperature higher than the current set temperature is set, and the processing from step S503 to step S508 is similarly repeated. If the current set temperature is the highest ambient temperature setting among the plurality of ambient temperature information input in step S501, or if one ambient temperature information is input in step S501, the temperature setting is Assuming no change (S509-No), the process proceeds to step S510.

  In step S <b> 510, the calculation unit 105 calculates the radiation irradiation unit 101 based on the received radius information Rgi of the focal point of the tube of the radiation irradiation unit 101 and the radiation detection position radius information Rfi of the radiation detection unit 102 for each received environmental temperature. And a correction parameter for the radius of rotation of the radiation detection unit 102 is generated. The calculation unit 105 calculates an error (Rg) between the rotation radius Rg of the radiation generation unit predetermined with respect to the rotation center O and the position Rgi of the radiation generation unit detected by the position detection unit 107 before photographing the subject P. The first correction parameter (G) that minimizes -Rgi) is calculated, and the position of the radiation generating unit is corrected (approximate) using the first correction parameter (G). In addition, the calculation unit 105 sets the rotation radius Rf of the radiation detection unit 102 determined in advance with respect to the rotation center O and the position Rfi of the radiation detection unit 102 detected by the position detection unit 107 before photographing the subject P. The second correction parameter (F) that minimizes the error (Rf−Rfi) is calculated, and the position of the radiation detection unit 102 is corrected (approximated) using the second correction parameter (F). A correction parameter generation method will be described with reference to FIG.

  In FIG. 6, Di is an angle based on the highest position of the radiation irradiation unit 101 at the time of the number index i, and Di corresponds to an angular interval obtained by dividing one round (360 degrees) around the subject by the number of shots imax. It is an angle to do. Further, as shown in FIG. 6, the radiation irradiation unit 101 and the radiation detection unit 102 face each other by 180 degrees about the rotation center O of the rotation unit 108. In step S510 of FIG. 5, the calculation unit 105 calculates the correction parameter G (first correction parameter) for correcting the error of the rotation radius of the radiation irradiation unit 101 and the error of the rotation radius of the radiation detection unit 102 for each environmental temperature. A correction parameter F (second correction parameter) to be corrected is generated.

  Based on the radius information Rgi of the focal point of the tube of the radiation irradiation unit 101 received from the position detection unit 107, the calculation unit 105 corrects the rotation radius error of the radiation irradiation unit 101 from the equation (2) by the least square method. The correction parameter G (first correction parameter) to be acquired is acquired. That is, the calculation unit 105 corrects the error between the design value (Rg) of the focal point of the tube and the radius information (Rgi) of the detected focal point of the tube from Equation (2). A parameter G (first correction parameter) is calculated.

Rg−Rgi = G · cosDi (2)
Similarly, the calculation unit 105 uses the least square method based on the radius information Rfi of the radiation detection position of the radiation detection unit 102 received from the position detection unit 107 to calculate the error of the rotation radius of the radiation detection unit 102 from Equation (3). A correction parameter F (second correction parameter) is corrected. That is, the calculation unit 105 minimizes the error between the design value (Rf) of the radiation detection position radius of the radiation detection unit 102 and the radius information (Rfi) of the detected radiation detection position from the equation (3). Such a correction parameter F (second correction parameter) is calculated.

Rf−Rfi = −F · cosDi (3)
If the correction parameter G (first correction parameter) can be acquired, the position of the radiation generating unit can be approximated using the correction parameter G (first correction parameter). That is, the detected radius information (Rgi) of the tube focus is approximated by the design value (Rg) of the focus radius of the tube, the correction parameter G (first correction parameter), and the rotation angle information (Di). can do. Similarly, if the correction parameter F (second correction parameter) can be acquired, the position of the radiation detection unit 102 can be approximated using the correction parameter F (second correction parameter). That is, the radius information (Rfi) of the detected radiation detection position is approximated by the design value (Rf) of the radius of the radiation detection position, the correction parameter F (second correction parameter), and the rotation angle information (Di). Can do. With the above arithmetic processing, the preliminary data acquisition processing before the start of photographing is completed.

  Next, processing from the start to the end of photographing of the subject by the radiation imaging apparatus 100 according to the second embodiment will be described. Among the processes from the start to the end of shooting of the subject, the difference from the process of the first embodiment is the shooting condition determination process in step S201 shown in FIG. 2, the transmission process of radius information Rgi and Rfi in step S206, and This is the position correction processing in step S302 shown in FIG.

  In the second embodiment, in step S201, the operator inputs the environmental temperature as a shooting condition in addition to the tube voltage kV, the tube current mA, and the number of shots imax by the shooting condition input unit of the shooting condition setting unit 103. Then, the operator operates an environmental temperature setting unit (not shown) to set the environmental temperature of the radiation imaging apparatus 100 to the environmental temperature input in step S201.

  In the second embodiment, the transmission processing of the radius information Rgi and Rfi in step S206 is omitted. In the second embodiment, the detection of the radius information Rgi, Rfi is not performed during the imaging process, and the detected radius information Rgi, Rfi is used as the correction parameter G and the pre-data acquisition process before imaging (FIG. 5). A process of correcting (approximate) using F is performed. In the imaging process in the second embodiment, the correction parameters G and F acquired by using the values calculated by the equations (2) and (3) for the radius information Rgi and Rfi in step S302 of FIG. 3, respectively. Based on the radius information corrected (approximated) using the radius information Rgi and Rfi, the position correction process of S302 is performed. At this time, the correction parameters G and F for correcting the radius of rotation are the correction parameters G and F corresponding to the environmental temperature input in step S201 among the correction parameters G and F calculated in the prior data acquisition process described in FIG. And the value of F is used.

  The calculation unit 105 approximates the position of the radiation generation unit using the correction parameter G (first correction parameter) calculated for each set environmental temperature, and the correction parameter F calculated for each set environmental temperature. The position of the radiation detection unit is approximated using (second correction parameter). Then, the calculation unit 105 corrects the signal output from the radiation detection unit 102 using the approximate position of the radiation generation unit and the position of the radiation detection unit, and generates a radiation image.

  In the first embodiment, the position correction processing of S302 is performed using the radius information Rgi (radiation generation unit position) and Rfi (radiation detection unit position) acquired in real time when the subject P is captured. In the embodiment, the radius information Rgi (position of the radiation generation unit) and Rfi (position of the radiation detection unit) are corrected (approximated) using the correction parameter acquired based on the result of the prior data acquisition process, and the correction (approximation) is performed. The position correction process of S302 is performed using the result.

  As correction of the signal output from the radiation detection unit, the calculation unit 105 calculates the position of the radiation generation unit approximated using the correction parameter G (first correction parameter) and the correction parameter F (second correction parameter). The position of the image sensor in the radiation detection unit 102 is corrected using the approximate position of the radiation detection unit used.

  According to the second embodiment, it is possible to provide a radiographic technique that can suppress a decrease in resolution of a radiographic image with higher accuracy. In the second embodiment, the position detection unit 107 may be provided in the radiation imaging apparatus at the time of factory shipment inspection or maintenance, and mounting on each radiation imaging apparatus becomes unnecessary, and the radiation imaging apparatus of the first embodiment. Compared with this configuration, the cost of the radiation imaging apparatus can be further reduced.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the third embodiment, the resolution reduction suppression method due to the deviation from the design values of the rotation radii of the radiation irradiation unit 101 and the radiation detection unit 102 is an imaging method emphasizing resolution based on the operator's selection or time. A configuration for changing whether the photographing method is important will be described.

  Here, as described in the first embodiment, the imaging method emphasizing resolution is an imaging method using information obtained by measuring in real time a subject whose deviation from the design value of the rotation radius is taken. In the imaging method emphasizing resolution, since the real-time measurement result can be reflected in the arithmetic processing (for example, step S213 in FIG. 2 and each step in FIG. 3), the reduction in resolution is suppressed and imaging with higher resolution is performed. It becomes possible.

  Further, the time-oriented imaging method is an imaging method using the trajectory information of the radiation irradiation unit 101 and the radiation detection unit 102 measured in advance as described in the second embodiment. In the time-oriented photographing method, since the calculation based on the result of measuring the deviation from the design value of the rotation radius in real time at the time of photographing is not performed during photographing, photographing can be performed in a shorter time.

  Below, in order to avoid duplication of description, the part which is different from 1st Embodiment and 2nd Embodiment is demonstrated. In the third embodiment, in step S201 shown in FIG. 2, in addition to the information about the shooting conditions, the shooting condition setting unit 103 determines whether the shooting method takes importance of the resolution according to the operation input by the operator via the shooting condition input unit. Accepts selection of important shooting methods. In the present embodiment, the imaging condition setting unit 103 functions as a selection unit that selects a correction mode in the radiation imaging apparatus 100 based on an operation input from the operator via the imaging condition input unit.

  In response to an operation input from the imaging condition input unit, the imaging condition setting unit 103 (selection unit) selects a resolution-oriented imaging method or a time-oriented imaging method. That is, by the operation input, the imaging condition setting unit 103 (selection unit) uses the radiation generation unit and the position of the radiation detection unit 102 detected by the position detection unit 107 during imaging of the subject, and the radiation detection unit 102. The imaging method in the first correction mode for correcting the signal output from the imaging method (imaging method focusing on resolution), or the position of the radiation generating unit approximated using the calculated first correction parameter before imaging the subject And a radiation detection unit approximated using the second correction parameter, and a photographing method (resolution-oriented photographing method) in a second correction mode for correcting a signal output from the radiation detection unit 102, select.

  The imaging condition setting unit 103 transmits the information regarding the input imaging conditions and the information indicating the selection result of the imaging method to the control unit 104, and the control unit 104 based on the transmitted information. ) To control. When the imaging method emphasizing resolution is selected, the control unit 104 controls the radiation imaging apparatus 100 (CT apparatus) so as to perform the processing of the first embodiment. On the other hand, when a time-oriented imaging method is selected in step S201, the control unit 104 controls the radiation imaging apparatus 100 (CT apparatus) to perform the process of the second embodiment.

  When a resolution-oriented shooting method is selected, the real-time measurement result can be reflected in the arithmetic processing, so that it is possible to perform shooting with higher resolution while suppressing a decrease in resolution. In addition, when a time-oriented imaging method is selected, the calculation based on the result of measuring the deviation from the design value of the rotation radius in real time at the time of imaging is not performed during imaging. It is possible to shorten the time until image display.

  Further, in the third embodiment, in step S215 shown in FIG. 2, the image display unit 106 displays the generated radiation image and the selected imaging method in combination on the display unit 110. Thus, the operator can identify which imaging method is used for the radiographic image of the subject.

  According to the configuration of the third embodiment, it is possible to perform radiation imaging based on a desired operation selected by the operator for a resolution-oriented imaging method or a time-oriented imaging method.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100: Radiation imaging apparatus, 101: Radiation irradiation unit, 102: Radiation detection unit,
103: shooting condition setting unit, 104: control unit, 105: calculation unit, 106: image display unit, 107: position detection unit, 108: rotation unit, 109: image storage unit

Claims (16)

Radiation having a radiation generation unit that generates radiation, a radiation detection unit that detects radiation emitted from the radiation generation unit, and a rotation unit that rotates the radiation generation unit and the radiation detection unit facing each other. A photographing device,
A position detection unit that detects a position of the radiation generation unit and the radiation detection unit;
A calculation unit that generates a radiographic image obtained by reconstructing three-dimensional information of a subject based on a signal output from the radiation detection unit;
The calculation unit corrects a signal output from the radiation detection unit using the radiation generation unit detected by the position detection unit and position information of the radiation detection unit, and generates the radiation image. A characteristic radiographic apparatus. The rotating unit rotates the radiation generating unit and the radiation detecting unit around a rotation center,
The radiation imaging apparatus according to claim 1, wherein the position detection unit detects a position of the radiation generation unit and a position of the radiation detection unit with respect to the rotation center.   The calculation unit is based on a rotation radius of the radiation generation unit and a rotation radius of the radiation detection unit that are predetermined with respect to the rotation center and a position detected by the position detection unit when the subject is imaged. The radiation imaging apparatus according to claim 2, wherein a signal output from the radiation detection unit is corrected.   The calculation unit, as correction of the signal output from the radiation detection unit, the predetermined rotation radius of the radiation generation unit and the rotation radius of the radiation detection unit, and the position detected by the position detection unit, The radiation imaging apparatus according to claim 3, wherein position correction of the image sensor in the radiation detection unit is performed based on the above.   The calculation unit performs a reconstruction filter process on the radiation image after position correction, and back-projects the radiation image after the reconstruction filter process, thereby generating a radiation image in which the three-dimensional information of the subject is reconstructed. The radiographic apparatus according to claim 4. The position detection unit is configured to be detachable from the radiation imaging apparatus,
The radiation imaging apparatus according to claim 1, wherein the position detection unit detects positions of the radiation generation unit and the radiation detection unit in a state where the position detection unit is attached to the radiation imaging apparatus. It further has a shooting condition setting unit for setting shooting conditions by an operation input from the input unit,
The imaging condition setting unit sets, based on the operation input, at least one environment temperature information or a plurality of environment temperature information in the imaging environment in which the radiation imaging apparatus is installed as the imaging condition. The radiation imaging apparatus according to claim 2 or 3. The arithmetic unit minimizes an error between a rotation radius of the radiation generation unit predetermined with respect to the rotation center and a position of the radiation generation unit detected by the position detection unit before photographing the subject. Calculating the first correction parameter to be
The radiation imaging apparatus according to claim 7, wherein the position of the radiation generation unit is approximated using the first correction parameter. The calculation unit minimizes an error between a rotation radius of the radiation detection unit predetermined with respect to the rotation center and a position of the radiation detection unit detected by the position detection unit before photographing the subject. Calculate the second correction parameter to
The radiation imaging apparatus according to claim 8, wherein the position of the radiation detection unit is approximated using the second correction parameter.   The calculation unit approximates the position of the radiation generation unit using the first correction parameter calculated for each of the set environmental temperatures, and the second calculation unit is calculated for each of the set environmental temperatures. The radiation imaging apparatus according to claim 9, wherein the position of the radiation detection unit is approximated using a correction parameter. The calculation unit generates the radiation image by correcting a signal output from the radiation detection unit using the approximate position of the radiation generation unit and the position of the radiation detection unit. Item 11. The radiographic apparatus according to Item 10.   The calculation unit corrects the signal output from the radiation detection unit, and approximates the position of the radiation generation unit approximated using the first correction parameter and the radiation detection unit approximated using the second correction parameter. The radiation imaging apparatus according to claim 9, wherein the position of the image sensor in the radiation detection unit is corrected using the position of the radiation detector. A selection unit for selecting an imaging method in the radiation imaging apparatus by an operation input from the input unit;
The selection unit includes:
Imaging in a first correction mode for correcting a signal output from the radiation detection unit using the radiation generation unit and the position of the radiation detection unit detected by the position detection unit at the time of imaging the subject. Method or
Before photographing the subject, using the position of the radiation generation unit approximated using the calculated first correction parameter and the position of the radiation detection unit approximated using the second correction parameter The radiographic apparatus according to claim 9, wherein an imaging method in a second correction mode that corrects a signal output from the radiation detection unit is selected. An image display unit for displaying the generated radiation image on a display unit;
The radiation imaging apparatus according to claim 13, wherein the image display unit displays the radiation image and the selected imaging method in combination on the display unit. Radiation having a radiation generation unit that generates radiation, a radiation detection unit that detects radiation emitted from the radiation generation unit, and a rotation unit that rotates the radiation generation unit and the radiation detection unit facing each other. A radiation imaging method in an imaging apparatus,
A position detecting step for detecting positions of the radiation generating unit and the radiation detecting unit;
A calculation step of generating a radiographic image reconstructed from the three-dimensional information of the subject based on a signal output from the radiation detection unit;
In the calculation step, using the position information of the radiation generation unit and the radiation detection unit detected in the position detection step, the signal output from the radiation detection unit is corrected to generate the radiation image. A characteristic radiography method.   The program for making a computer perform the process of the radiography method of Claim 15.

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