JP2012047671A - Radiation tomographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation tomographic apparatus that is suitable to diagnosis by comparing two images differing in photographic condition with each other.SOLUTION: The radiation tomographic apparatus includes a position specification part 21 which maps a generation position of radiation in three dimensions; a map deformation part 23 which virtually deforms the three-dimensional map (m) generated by the position specification part 21; and a deformed MIP image generation part 24 which generates a deformed MIP image P1 having the generation position of the radiation mapped in two dimensions using the deformed three-dimensional map (n) having been virtually deformed. Consequently, the deformed MIP image P1 is obtained without deforming a breast B of an analyte M, but is an image in which the breast B of the analyte M having been deformed to the same extent as an image photographed with the breast B of the analyte M deformed is photographed, which is suitable to diagnosis.

Description

  The present invention relates to a radiation tomography apparatus that detects an annihilation radiation pair emitted from a subject and images a radiopharmaceutical distribution in the subject, and more particularly to a radiation tomography apparatus for breast examination.

  In medical institutions, radiation tomography apparatuses that image the distribution of radiopharmaceuticals are deployed. A specific configuration of such a radiation tomography apparatus will be described. A conventional radiation tomography apparatus includes a detector ring in which radiation detectors that detect radiation are arranged in an annular shape. The detector ring detects a pair of radiations (an annihilation radiation pair) emitted in opposite directions from the radiopharmaceutical in the subject. Such a radiation tomography apparatus is called a PET (positron emission tomography) apparatus (see Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4).

  A case where breast examination is performed using such a radiation tomography apparatus will be described. In breast examination to detect breast cancer, first, an X-ray projection image of the breast is acquired by mammography to know the internal structure of the breast. In order to conduct further detailed examination, a tomographic image is obtained by a PET apparatus and a breast biopsy is performed. As described above, in breast examination, a method of first obtaining an X-ray fluoroscopic image prior to various examinations is common. This is because an X-ray fluoroscopic image can know structural abnormality inside the breast.

  An X-ray fluoroscopic image of a breast is obtained by mammography while the breast is sandwiched between two opposing plates and the breast is pressed until flexibility is lost. In this way, imaging is performed with a breast whose shape is not fixed temporarily set to be inflexible. As described above, an advantage of performing imaging while sandwiching the breast between plates is that the X-ray dose at the time of obtaining an X-ray fluoroscopic image can be suppressed. That is, the breast sandwiched between the two plates is deformed into a flat shape in the direction in which the plates face each other. If an X-ray fluoroscopic image is taken so that X-rays pass in the thickness direction of the breast having a flat shape, the distance that the X-rays pass through the breast can be shortened. As a result, the X-ray dose incident on the breast can be suppressed because imaging can be performed with a small X-ray dose as much as the distance is shortened.

  Acquisition of a tomographic image of a breast by a PET apparatus is performed by detecting an annihilation radiation pair generated from the inside of the breast in a state where the breast is inserted into a ring-shaped detector ring. The data obtained by this examination is the generation source of annihilation radiation pairs arranged three-dimensionally. Based on this, the PET device generates annihilation radiation pairs in the cross section when the breast is cut at an arbitrary slice plane. A tomographic image in which the source is mapped can be obtained.

  Thus, the mammographic x-ray image of the breast can be obtained in a state where the breast is pressed with two plates, and the tomographic image in the PET apparatus is a tomographic image acquired without pressing the breast. It is. Therefore, the X-ray fluoroscopic image and the tomographic image obtained by the PET apparatus are different in the state of the reflected breast even though the same breast is photographed. That is, in the case of an X-ray fluoroscopic image, it is an image obtained by projecting a flatly deformed breast onto a plane, not a tomographic image.

JP 2009-77780 A JP 2008-161283 A International Publication No. 2007-119459 JP 2007-271252 A

  However, the conventional radiation tomography apparatus has the following problems. In other words, after obtaining an X-ray fluoroscopic image by mammography, it is not possible to compare and examine the X-ray fluoroscopic image and the tomographic image even if a tomographic image obtained by a PET apparatus is acquired in more detail. is there.

  As described above, the X-ray fluoroscopic image and the tomographic image of the PET apparatus differ in the state of the captured breast. The X-ray fluoroscopic image shows a flat breast pressed between two plates, while the PET tomographic image shows a tomographic image of the breast as it is without being pressed. Thus, the shapes of the breasts reflected in both images are different from each other. The X-ray fluoroscopic image is a projection image obtained by fluoroscopying the breast from a certain direction, while the PET tomographic image is a tomographic image obtained by cutting the breast along an arbitrary slice plane. That is, the X-ray fluoroscopic image is a projection image in which position information in the direction in which X-rays are transmitted is lost, and the captured image is different from the tomographic image obtained by PET.

  When performing a breast examination, it is desirable that a fluoroscopic image and an image obtained by a PET apparatus can be compared. This is because it is convenient for diagnosis if it is possible to know how the mass is reflected in the image of the PET apparatus assuming that the mass is reflected in the breast in the X-ray fluoroscopic image. However, the fluoroscopic image and the image of the PET apparatus are taken under different conditions and are not images that can be compared with each other. In the conventional configuration, such a situation hinders diagnosis.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a radiation tomography apparatus suitable for diagnosis by enabling comparison of two images having different imaging conditions. It is in.

The present invention has the following configuration in order to solve the above-described problems.
That is, the radiation tomography apparatus according to the present invention three-dimensionally maps a radiation generation position based on a detector ring for detecting radiation generated in a subject and detection data acquired from the detector ring. Recognize the shape of the subject reflected in the three-dimensional map generated by the position specifying means and the position specifying means, and how the shape of the subject is deformed by virtually deforming it as position information Destination information acquisition means for acquiring destination information to be shown, map deformation means for virtually deforming a three-dimensional map generated by the position specifying means based on the destination information, and a deformed three-dimensional map virtually deformed And a deformed image generating means for generating a deformed image in which the generation position of radiation is mapped two-dimensionally.

  [Operation and Effect] According to the present invention, the position specifying means for mapping the generation position of the annihilation radiation pair three-dimensionally, the map deforming means for virtually deforming the three-dimensional map generated by the position specifying means, and the virtual And a deformed image generating means for generating a deformed image in which the generation positions of annihilation radiation pairs are two-dimensionally mapped using a deformed deformed three-dimensional map. Thereby, the generation position of the annihilation radiation pair mapped three-dimensionally is changed to a state in which the subject is deformed, and then a deformed image is generated. Therefore, although the deformed image is obtained without deforming the subject, the subject is deformed to the same extent as the image photographed with the subject deformed. It is an image. Thereby, the radiation tomography apparatus which can compare both images and can provide the information which assists a diagnosis can be provided.

  Further, in the above-mentioned radiation tomography apparatus, a radiation source that irradiates radiation from the outside of the subject, a radiation detection means that detects radiation that has been irradiated from the radiation source and then transmitted through the subject, and a subject that is deformed by pressing. A pair of plates for sandwiching the specimen, a moving means for moving the plates, a movement control means for controlling the moving means, and the pressed subject is irradiated with radiation, and the detection signal output from the radiation detecting means at that time is output. A radiographic image generation unit that generates a radiographic image that is an image captured in a state where the subject is deformed based on the image, and the map deformation unit includes a movement destination that indicates the deformation of the subject that is reflected in the radiographic image It is more desirable to operate based on information.

  [Operation / Effect] The above-described configuration is obtained by adding a configuration for acquiring an image photographed with a subject deformed to the configuration of the present invention. That is, the above-described configuration includes a pair of plates that sandwich a subject that is deformed by pressing, and the subject is imaged with radiation in a deformed state. The deformation three-dimensional map is generated based on the movement destination information indicating the deformation of the subject by the plate. As a result, the shape of the subject deformed in the pressed state matches the shape of the subject in the deformed three-dimensional map obtained by image conversion, and the comparison of both images is further facilitated.

  In the above-described radiation tomography apparatus, the deformed image generating means selects a maximum value indicating that radiation is most generated among the values of the deformed three-dimensional map located on a straight line crossing the deformed three-dimensional map. It is more desirable to generate a deformed image by projecting the selected maximum value onto a certain projection surface and repeating this operation for different straight lines to place pixels indicating the maximum value for each straight line on the projection surface. .

  [Operation / Effect] The above-described configuration shows a specific configuration of the deformed image generating means. That is, the deformed image generating means is an image obtained by projecting the deformed three-dimensional map onto a certain projection plane. As a result, it is possible to generate a deformed image in which an image equivalent to the subject image reflected in the fluoroscopic image with the subject deformed is reflected.

  In the above-described radiation tomography apparatus, it is more desirable to further include a superimposing unit that superimposes an image captured in a state where the subject is deformed and a deformed image.

  [Operation / Effect] The above-described configuration shows a more specific configuration of the present invention. That is, the above-described configuration includes a superimposing unit that superimposes both images. This makes diagnosis using both images easier.

  In the above-described radiation tomography apparatus, the overlaying unit moves and rotates at least one of the image and the deformed image taken with the subject deformed with respect to the other image. It is more desirable to have alignment means for matching the positions of the images.

  [Operation / Effect] The above-described configuration shows a more specific configuration of the present invention. That is, when the images are superimposed, the position where the images are superimposed can be changed. This ensures that both images are superimposed and diagnosis is easier.

  In the above-described radiation tomography apparatus, it is more preferable that the deformed image generating means operates by acquiring movement destination information that is referred to based on distance data indicating the distance between the pair of plates output from the movement control means.

  [Operation / Effect] The above-described configuration shows a more specific configuration of the present invention. That is, if the three-dimensional map is deformed based on the distance data indicating the separation distance between the pair of plates output from the movement control means, and the deformed image is generated based on the deformed three-dimensional map, the two images are reflected. The shape of the deformed subject more accurately matches, and useful information can be provided by diagnosis.

  In the above-mentioned radiation tomography apparatus, the subject to be deformed is the breast, and it is more desirable if it is for breast examination.

  [Operation / Effect] The above-described configuration shows a more specific configuration of the present invention. That is, if the present invention is applied to breast examination, it is possible to provide a radiation tomography apparatus that is easy to diagnose even when radiography of a deformed breast is performed.

  According to the present invention, the position specifying means for mapping the generation position of the annihilation radiation pair three-dimensionally, the map deforming means for virtually deforming the three-dimensional map generated by the position specifying means, and the virtual deformed And a deformed image generating means for generating a deformed image in which the generation positions of annihilation radiation pairs are two-dimensionally mapped using a deformed three-dimensional map. Thereby, although the deformed image is obtained without deforming the subject, the subject deformed to the same extent as the image photographed with the subject deformed is reflected. It is an image.

1 is a functional block diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 1 is a perspective view illustrating a configuration of a radiation detector according to Embodiment 1. FIG. It is a schematic diagram explaining the press of the breast which concerns on Example 1. FIG. 3 is a flowchart for explaining the operation of the radiation tomography apparatus according to Embodiment 1. FIG. 6 is a schematic diagram illustrating generation of a modified MIP image according to the first embodiment. 6 is a functional block diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 2. FIG.

<Configuration of radiation tomography system>
Embodiments of a radiation tomography apparatus according to the present invention will be described below with reference to the drawings. The gamma rays in Example 1 are an example of the radiation of the present invention. The configuration of the first embodiment is a mammography apparatus for breast examination. FIG. 1 is a functional block diagram illustrating a specific configuration of the radiation tomography apparatus according to the first embodiment. The radiation tomography apparatus 9 according to the first embodiment includes a gantry 11 that introduces the breast B of the subject M from the z direction, and a ring shape that introduces the breast B of the subject M provided inside the gantry 11 from the z direction. Detector ring 12. The inner hole provided in the detector ring 12 has a cylindrical shape (more precisely, an n prism) extending in the z direction. Therefore, the detector ring 12 itself extends in the z direction. Note that the area of the inner hole of the detector ring 12 is a field of view that can generate a tomographic image of the radiation tomography apparatus 9. The z direction is along the direction in which the central axis of the detector ring 12 extends.

  The shielding plate 13 is made of tungsten or the like. Since the radiopharmaceutical is also present in a portion other than the breast B of the subject M, radiation is also generated from there. However, when radiation generated from other than the region of interest enters the detector ring 12, it interferes with tomographic imaging. Therefore, a ring-shaped shielding plate 13 is provided so as to cover one end of the detector ring 12 on the side close to the subject M in the z direction.

  The clock 19 sends time information as a serial number to the detector ring 12. The detection data output from the detector ring 12 is given time information indicating when the γ-ray is detected, and is input to the coincidence counting unit 20 described later.

  The configuration of the detector ring 12 will be described. In the detector ring 12, n radiation detectors 1 are arranged in a virtual circle on a plane perpendicular to the z direction (center axis direction) to form one unit ring. For example, three unit rings are arranged in the z direction to form a detector ring 12.

  The configuration of the radiation detector 1 will be briefly described. FIG. 2 is a perspective view illustrating the configuration of the radiation detector according to the first embodiment. As shown in FIG. 2, the radiation detector 1 includes a scintillator 2 that converts radiation into light, and a photodetector 3 that detects light. A light guide 4 for transmitting and receiving light is provided at a position where the scintillator 2 and the photodetector 3 are interposed.

The scintillator 2 is configured by scintillator crystals arranged three-dimensionally. The scintillator crystal is composed of Lu _{2 (1-X)} Y _2X SiO ₅ (hereinafter referred to as LYSO ₎ in which Ce is diffused. The light detector 3 can specify the light generation position of which scintillator crystal emits light, and also specifies the light intensity and the time when the light is generated. Can do. The scintillator 2 having the configuration of the first embodiment is merely an example of an aspect that can be adopted. Therefore, the configuration of the present invention is not limited to this.

  The detection data output from the detector ring 12 is sent to the coincidence counting unit 20 (see FIG. 1). Then, it is determined that the two radiations incident on the detector ring 12 almost simultaneously are annihilation γ-ray pairs caused by the radiopharmaceutical in the subject (simultaneous counting). The coincidence unit 20 sends the information of the scintillator crystals constituting the detector ring 12 that have been simultaneously counted to the position specifying unit 21. The positional relationship of the scintillator crystals in the coincidence count indicates the position where the annihilation γ-ray pair is incident on the detector ring 12 and the direction in which the annihilation γ-ray pair is incident. The number of annihilation γ-ray pairs detected and the energy intensity of annihilation γ-rays stored for each combination of scintillator crystals indicates the variation in the generation of annihilation γ-ray pairs in the subject, and is necessary for mapping radiopharmaceuticals. Information. The determination of the coincidence of the detected data by the coincidence unit 20 uses time information given to the detected data by the clock 19. The position specifying unit 21 corresponds to the position specifying means of the present invention.

  The position specifying unit 21 receives the data on the generation position and radiation intensity of the annihilation γ-ray pair output from the coincidence counting unit 20, and generates a three-dimensional map m in which the generation position of the annihilation γ-ray is mapped in a three-dimensional space. Generate.

  The three-dimensional map m is sent to the movement destination information acquisition unit 22, the map deformation unit 23, and the tomographic image generation unit 26. The map deforming unit 23 virtually deforms the three-dimensional map m based on the destination information T stored in the storage unit 37 to generate a deformed three-dimensional map n. This destination information T is generated by the destination information acquisition unit 22 based on the three-dimensional map m. Based on the three-dimensional map m, the tomographic image generation unit 26 acquires a tomographic image D in which the generation source of annihilation γ-ray pairs in a cross section when the breast B is cut along a predetermined slice plane is two-dimensionally mapped. . The tomographic image D at this time is an axial image in which the breast B of the subject M is cut, for example. The destination information acquisition unit 22 corresponds to a destination information acquisition unit of the present invention, and the map deformation unit 23 corresponds to a map deformation unit of the present invention.

  The destination information T acquired by the destination information acquisition unit 22 will be described. The destination information T is position information indicating how the breast B is deformed. That is, the movement destination information T is data indicating how the breast B is deformed by the pair of sandwiching plates when the X-ray fluoroscopic image is taken. Specifically, the movement destination information T is a related table in which three-dimensional coordinates before deformation and three-dimensional coordinates after deformation are related.

  The movement destination information T will be described more specifically. For example, assume that the three-dimensional coordinates of the point a1 in the breast shown in FIG. 3A are (x, y, z). When the breast B is pressed and deformed, the point a1 is moved to the point a2 in the breast shown in FIG. The three-dimensional coordinates of this point a2 are assumed to be (X, Y, Z). The destination information T is an association table that associates the coordinates (x, y, z) before deformation and the coordinates (X, Y, Z) after deformation. The map deforming unit 23 refers to the destination information T and moves the generated intensity data of the annihilation γ-ray pair located at the point a1 in the three-dimensional map m to the point a2 to generate the deformed three-dimensional map n.

  A method for acquiring the destination information T will be described. The destination information T can be obtained by performing a simulation to deform the breast B on the three-dimensional map m under a predetermined condition. When the breast B in the three-dimensional map m is deformed, the movement destination information acquisition unit 22 first extracts the contour of the breast B in the three-dimensional map. Thus, the movement destination information acquisition unit 22 recognizes the shape of the breast B that is hemispherical.

  Then, the movement destination information acquisition unit 22 deforms the acquired shape of the breast B by simulation. This simulation is performed under the condition that the surface area of the breast B does not change, the inflection point does not increase, and the density inside the breast B does not change. Thereby, it is possible to know how the breast B is deformed when the breast B is compressed from both sides by a plane orthogonal to a certain direction. In the simulation, since the physical properties of the breast B are limited as described above, the obtained result is close to the actual deformation of the breast B. Thus, the breast B in the three-dimensional map m is expanded by simulation and becomes a flat shape. This flat shape indicates the shape of the breast B in the modified three-dimensional map n, and matches the shape of the breast B in the fluoroscopic image.

  The movement destination information acquisition unit 22 tracks where each position of the breast B before deformation moves after deformation by simulation, and movement destination information in which coordinates before deformation and coordinates after deformation in the breast B are related. Get T.

  Acquisition of the destination information T by the destination information acquisition unit 22 is performed every time the three-dimensional map m is acquired. Therefore, the movement destination information T is performed every time the breast B is imaged by the radiation tomography apparatus 9.

  The deformed three-dimensional map n is sent to the deformed MIP image generator 24. The modified MIP image generation unit 24 generates a modified MIP image P1 in which the generation positions of annihilation γ-ray pairs are two-dimensionally mapped based on a modified three-dimensional map n shown in a three-dimensional space. The modified MIP image generation unit 24 corresponds to a modified image generation unit of the present invention. The deformed MIP image P1 corresponds to the deformed image of the present invention.

  The display unit 36 displays the deformed MIP image P1 and the tomographic image D, and the console 35 allows the operator to input various operations performed on the radiation tomography apparatus 9. The storage unit 37 includes detection data output from the detector ring 12, coincidence counting data generated by the coincidence counting unit 20, data generated by the operation of each unit such as tomographic images, destination information T and each unit referred to by the map deformation unit 23 All of the parameters that are referred to during the operation are stored.

  The radiation tomography apparatus 9 includes a main control unit 41 that comprehensively controls each unit. The main control unit 41 is constituted by a CPU, and realizes the respective units 19, 20, 21, 22, 23, 24, 25, and 26 by executing various programs. In addition, each above-mentioned part may be divided | segmented and implement | achieved by the control apparatus which takes charge of them.

<Operation of radiation tomography system>
Next, the operation of the radiation tomography apparatus 9 according to the first embodiment will be described. In order to perform breast examination, as shown in FIG. 4, the breast B is inserted into the detector ring 12 (breast insertion step S1), and detection of radiation emitted from the breast B is started (detection start step S2). . Then, a three-dimensional map m is generated from the detection data output from the detector ring 12 (three-dimensional map generation step S3), and a modified three-dimensional map n is generated based on the three-dimensional map m (three-dimensional modified map). Generation step S4). Then, a deformed MIP image P1 is generated based on the deformed three-dimensional map n (deformed image generating step S5), and the deformed MIP image P1 is displayed (display step S6). Hereinafter, these steps will be described in order.

  It is assumed that an X-ray fluoroscopic image of the breast B has been acquired prior to explaining the operation of the radiation imaging apparatus. The X-ray fluoroscopic image of the breast B was taken in a state where the breast B of the subject M was pressed with a sandwich plate and deformed into a flat shape, and the untransformed breast B shown in FIG. Is modified as shown in FIG. 3B at the time of photographing. The X-ray fluoroscopic image is taken so that the area in which the flat breast B is reflected in the image is the largest, and is taken from the direction in which the breast B is pressed with a sandwiching plate. Therefore, as can be seen from a comparison between FIG. 3A and FIG. 3B, the breast B is enlarged and appears in the X-ray fluoroscopic image. Specifically, the projection image of the breast B is reflected in a plane parallel to the plane pressing the breast B in the X-ray fluoroscopic image.

<Breast insertion step S1>
First, a radiopharmaceutical is injected into the subject M. When a predetermined time has elapsed from this point, the breast B of the subject M is inserted into the detector ring 12. FIG. 1 shows a state in which this operation is completed.

<Detection start step S2>
When the surgeon gives an instruction to detect the annihilation gamma ray pair through the console 35, the detector ring 12 starts sending detection data to the coincidence counting unit 20. The detection data transmitted at this time is a data set in which the incident position of the γ-ray detector ring 12, energy, and incident time are related.

<Three-dimensional map generation step S3>
The coincidence unit 20 performs coincidence of the detected data and sends the result to the position specifying unit 21. The position specifying unit 21 is provided with a three-dimensional matrix, and generates a three-dimensional map m in which the position inside the breast and the generation intensity of the annihilation gamma ray pair are related. This three-dimensional map m is detection data for the breast B in the state of FIG.

<Three-dimensional deformation map generation step S4>
The three-dimensional map m is sent to the map deformation unit 23. The operation of the map deformation unit 23 is the most characteristic in the present invention. That is, the map deforming unit 23 generates a new deformed three-dimensional map n based on the three-dimensional map m based on the destination information T acquired by the destination information acquiring unit 22. By the operation of the map deforming unit 23, the position information of the detection data of the annihilation γ-ray pair held on the three-dimensional map m in the state of the breast B in FIG. ) Is converted into position information of the state of the breast B. That is, the map deforming unit 23 virtually deforms the breast B in the three-dimensional map so as to have the same shape as the X-ray fluoroscopic image in which the breast B in the deformed state shown in FIG. To make it happen.

<Deformed image generation step S5>
The deformed three-dimensional map n is sent to the deformed MIP image generator 24. The modified MIP image generation unit 24 generates a modified MIP image P1 using the modified three-dimensional map n. The modified MIP image P1 will be described. As shown in FIG. 5, the deformed three-dimensional map n holds imaging data of annihilation γ-ray pairs in the breast B of the pressed subject M. The straight line L is assumed to be a straight line orthogonal to the plane pressing the breast B. The modified MIP image generation unit 24 corresponds to a modified image generation unit of the present invention.

  The modified MIP image generation unit 24 selects the maximum pixel value for the straight line L that crosses the modified three-dimensional map n. Specifically, the deformed MIP image generation unit 24 selects a pixel N having the maximum brightness among the pixels existing on the straight line L shown by diagonal lines in FIG. 5 among the pixels of the deformed three-dimensional map n. . The deformed MIP image generating unit 24 arranges the pixel value of the pixel N at a position indicating a point p of the plane F parallel to the plane pressing the breast B in the deformed MIP image P1.

  The modified MIP image generation unit 24 repeats the same operation while moving the point p on the plane F (projection plane), and changes the straight line L each time, so that the maximum luminance (most extinct γ-ray pairs are generated). A pixel having a luminance of The straight line L is always orthogonal to the plane F while being changed. The pixel values of the selected pixels are sequentially arranged in the generated modified MIP image P1, and a modified MIP image P1 in which the maximum values are arranged for each straight line L is generated. The deformed MIP image P1 has a shape as if the breast B of the pressed subject M is projected onto the plane F.

<Display step S6>
The deformed MIP image P1 is sent to the alignment unit 25. The alignment unit 25 can edit the deformed MIP image P1 by rotating and moving the deformed MIP image P1 so that the previously acquired X-ray fluoroscopic image and the deformed MIP image P1 can be easily compared. Yes. This editing is performed by an operator giving an instruction through the console 35. The deformed MIP image P1 is displayed on the display unit 36 after being edited by the alignment unit 25. The display unit 36 may display a previously acquired X-ray fluoroscopic image in addition to the deformed MIP image P1. At this time, the breast B of the subject M is pressed into the X-ray fluoroscopic image and is reflected in a flat shape. If the deformed MIP image P1 is an image obtained by virtually pressing the breast B held in the three-dimensional map m, the breast B reflected in the deformed MIP image P1 is also an X-ray fluoroscopic image. Like, it has a flat shape. Therefore, the breast B reflected in both images is easy to compare.

  Further, the X-ray fluoroscopic image is mapped with the intensity of the transmitted X-ray, whereas the deformed MIP image P1 is mapped with the maximum generation intensity of radiation (or the maximum density of the radiopharmaceutical). On the other hand, both the X-ray fluoroscopic image and the deformed MIP image P1 are images when projected onto a plane parallel to the plane pressing the breast B. According to this, although the meanings of the mapped data are different in both images, the methods for imprinting the breast B are the same. Therefore, both images are images showing internal information of the breast B that can be compared.

  In addition, the tomographic image D generated by the tomographic image generation unit 26 can be displayed on the display unit 36 in accordance with an operator instruction performed via the console 35. This tomographic image D is generated from the three-dimensional map m before deformation.

  As described above, according to the first embodiment, the position specifying unit 21 that maps the generation position of the annihilation gamma ray pair three-dimensionally, and the map that virtually deforms the three-dimensional map m generated by the position specifying unit 21. A deforming unit 23 and a deformed MIP image generating unit 24 that generates a deformed MIP image P1 in which the generation positions of annihilation γ-ray pairs are mapped two-dimensionally using a virtually deformed deformed three-dimensional map n. ing. As a result, the generation position of the annihilation γ-ray pair mapped three-dimensionally is changed to a state in which the breast B of the subject M is deformed, and then a deformed MIP image P1 is generated. Therefore, although the deformed MIP image P1 is obtained without deforming the breast B of the subject M, the deformed MIP image P1 is almost the same as an image taken in a state where the breast B of the subject M is deformed. It is an image in which the breast B of the subject M deformed to is reflected. Thereby, the radiation tomography apparatus 9 which can compare and easily diagnose both images can be provided.

  The deformed MIP image generation unit 24 is an image obtained by projecting the deformed three-dimensional map n onto a certain projection plane. As a result, it is possible to generate a deformed MIP image P1 in which an image equivalent to the breast image of the subject M that is reflected in an image that has been fluoroscopically photographed while the breast B of the subject M is deformed.

  Thus, if Example 1 is applied to a breast examination, the radiation tomography apparatus 9 which can perform a diagnosis easily even if X-ray imaging of the deformed breast B is performed can be provided.

  Next, a radiation tomography apparatus according to Embodiment 2 will be described. The radiation tomography apparatus 49 according to the second embodiment has a configuration in which each part provided for the purpose of acquiring an X-ray fluoroscopic image is provided in the radiation tomography apparatus 9 according to the first embodiment. Therefore, description of each part common to the configuration of the first embodiment is omitted. FPD is an abbreviation for flat panel detector.

<Overall configuration of radiation tomography apparatus 49>
First, the configuration of the radiation tomography apparatus 49 according to the second embodiment will be described. As shown in FIG. 6, the radiation tomography apparatus 49 includes a pair of sandwich plates 52a and 52b that press the breast B of the subject M, an X-ray tube 53 that irradiates X-rays toward the sandwich plate 52a, and a sandwich plate. 52a, breast B, and sandwiching plate 52b in this order, and an FPD 54 that detects X-rays emitted from the sandwiching plate 52b. The X-ray tube 53 corresponds to the radiation source of the present invention, and the FPD 54 corresponds to the radiation detection means of the present invention. In the present invention, the FPD 54 and the radiation detector 1 are different concepts.

  The sandwiching plate moving mechanism 57 is provided for the purpose of causing the pair of sandwiching plates 52a and 52b to approach and separate from each other. The sandwiching plate movement control unit 58 controls this. The pair of sandwich plates 52a and 52b arranged in parallel by the sandwich plate moving mechanism 57 can move in a direction orthogonal to the direction in which the plates spread. The sandwiching plate movement control unit 58 corresponds to the movement control unit of the present invention, and the sandwiching plate moving mechanism 57 corresponds to the moving unit of the present invention.

  The X-ray tube control unit 56 is provided for the purpose of controlling the X-ray tube 53 with a predetermined tube current, tube voltage, and pulse width. The FPD 54 detects X-rays emitted from the X-ray tube 53 and transmitted through the subject M, and generates a detection signal. This detection signal is sent to the fluoroscopic image generation unit 61, where an X-ray fluoroscopic image P2 in which a projection image of the subject M is reflected is generated. The superimposing unit 62 superimposes the X-ray fluoroscopic image P2 and the deformed MIP image P1 aligned by the alignment unit 25 to generate a composite image P3. Since the shapes of the breasts B appearing in both the images P1 and P2 that are the basis of the composite image P3 are the same, the breasts B appearing in both the images are overlapped without being shifted and appear on the composite image P3. Become. The X-ray fluoroscopic image P2 corresponds to the radiographic image of the present invention, and the fluoroscopic image generation unit 61 corresponds to the fluoroscopic image generation means of the present invention. The overlapping unit 62 corresponds to the overlapping unit of the present invention.

<Operation of radiation tomography system>
Next, the operation of the radiation tomography apparatus 49 will be described. First, when the surgeon gives an instruction to the console 35, the breast B of the subject M is sandwiched and pressed between the pair of sandwich plates 52a and 52b. At this time, the breast B has a flat shape as shown in FIG. When the operator gives an instruction to start X-ray irradiation to the console 35, X-rays are emitted from the X-ray tube 53, and an X-ray fluoroscopic image P2 is acquired. Immediately after giving the instruction to start X-ray irradiation, the sandwiching plate movement control unit 58 sends the distance between the pair of sandwiching plates 52 a and 52 b to the destination information obtaining unit 22.

  After the X-ray fluoroscopic image P2 is acquired, the breast B of the subject M is released from between the pair of sandwich plates 52a and 52b after being released from being pressed by the pair of sandwich plates 52a and 52b. Is inserted inside. And each operation | movement of step S1-S6 demonstrated in Example 1 will be performed. In the second embodiment, in the three-dimensional deformation map generation step S4, the movement destination information acquisition unit 22 outputs the clip plates 52a and 52b output from the clip plate movement control unit 58 when the shape of the breast B is deformed by simulation. The deformation three-dimensional map n is generated using the separation distance as one of the deformation conditions. Thereby, a more accurate simulation becomes possible. The modified MIP image generation unit 24 operates by changing the movement destination information T that is referred to based on the distance data that indicates the separation distance between the pair of plates that is output by the sandwiching plate movement control unit 58. The sandwich plates 52a and 52b correspond to the plates of the present invention.

  Then, the composite image P3 generated by the overlapping unit 62 is displayed on the display unit 36, and the inspection is completed.

  As described above, the above-described configuration is obtained by adding a configuration for acquiring an image captured in a state where the breast B of the subject M is deformed to the configuration of the first embodiment. That is, the above-described configuration includes a pair of sandwich plates 52a and 52b that sandwich the breast B of the subject M that is deformed by pressing, and the breast B of the subject M is imaged by X-rays in a deformed state. The deformation three-dimensional map n is generated based on the movement destination information T indicating the deformation of the breast B of the subject M by the sandwich plates 52a and 52b. As a result, the shape of the breast B of the subject M deformed in the pressed state matches the shape of the breast B of the subject M in the deformed three-dimensional map n obtained by image conversion, and the two image images are compared. Becomes even easier.

  The above-described configuration includes the superimposing unit 62 that superimposes both images. This makes diagnosis using both images easier.

  The present invention is not limited to the above-described configuration and can be modified as follows.

  (1) According to the configuration of each embodiment, the alignment unit 25 is configured to move and rotate the deformed MIP image P1 with respect to the X-ray fluoroscopic image. However, the present invention is not limited to this configuration. A configuration may be adopted in which the fluoroscopic image is deformed with respect to the deformed MIP image P1.

  (2) According to the configuration of each embodiment, the deformed MIP image P1 is generated. Instead of this image, for example, it is obtained by projecting a value other than the maximum value in the deformed three-dimensional map n onto a plane. An image other than the MIP image to be used can also be used.

  (3) The present invention is not limited to breast examination, and can be applied to all examinations for diagnosing a deformed subject M.

(4) The scintillator crystal referred to in each of the above examples is composed of LYSO, but in the present invention, instead of LGSO (Lu _{2 (1-X)} G _2X SiO ₅ ) or GSO (Gd ₂ The scintillator crystal may be made of other materials such as SiO ₅ ). According to this modification, it is possible to provide a method of manufacturing a radiation detector that can provide a cheaper radiation detector.

  (5) In each of the embodiments described above, the photodetector is composed of a photomultiplier tube, but the present invention is not limited to this. Instead of the photomultiplier tube, a photodiode, an avalanche photodiode, a semiconductor detector, or the like may be used.

m 3D map n Modified 3D map P1 Modified MIP image (modified image)
P2 X-ray fluoroscopic image (radiological fluoroscopic image)
T destination information 12 detector ring 21 position specifying unit (position specifying means)
22 Destination information acquisition unit (Destination information acquisition means)
23 Map deformation part (map deformation means)
24 Modified MIP image generator (modified image generator)
25 Positioning part (Positioning means)
52a, 52b sandwich plate (plate)
53 X-ray tube (radiation source)
54 FPD (radiation detection means)
57 Clipping plate moving mechanism (moving means)
58. Clipping plate movement control unit (movement control means)
61 Perspective image generation unit (perspective image generation means)
62 Superposition part (superposition means)

Claims (7)

A detector ring for detecting radiation generated in the subject;
Position specifying means for mapping a radiation generation position on a three-dimensional basis based on detection data acquired from the detector ring;
Destination information that indicates how the shape of the subject is deformed by recognizing the shape of the subject reflected in the three-dimensional map generated by the position specifying means and virtually deforming it. Destination information acquisition means for acquiring
Map deformation means for virtually deforming the three-dimensional map generated by the position specifying means based on the destination information;
A radiation tomography apparatus comprising: a deformed image generating unit configured to generate a deformed image in which radiation generation positions are two-dimensionally mapped using a virtually deformed deformed three-dimensional map. The radiation tomography apparatus according to claim 1,
A radiation source that emits radiation from outside the subject;
Radiation detecting means for detecting radiation that has passed through the subject after being irradiated from the radiation source;
A pair of plates that sandwich a subject deformed by pressing;
Moving means for moving the plate;
Movement control means for controlling the movement means;
Radiation image generation for irradiating the pressed subject with radiation and generating a radioscopic image that is an image taken in a state where the subject is deformed based on the detection signal output from the radiation detection means at that time And further comprising means
The radiation tomography apparatus according to claim 1, wherein the map deformation means operates based on movement destination information indicating deformation of the subject reflected in the radiographic image. The radiation tomography apparatus according to claim 1 or 2,
The deformed image generating means selects a maximum value selected by selecting a maximum value indicating that radiation is most generated among the values of the deformed three-dimensional map located on a straight line crossing the deformed three-dimensional map. The tomographic imaging apparatus is characterized in that the modified image is generated by arranging pixels indicating the maximum value of each straight line on the projection plane by repeating this operation for different straight lines. . The radiation tomography apparatus according to any one of claims 1 to 3,
A radiation tomography apparatus, further comprising: a superimposing unit that superimposes the image captured in a deformed state of the subject and the deformed image. The radiation tomography apparatus according to claim 4,
The superimposing means moves and rotates at least one of the image captured with the subject deformed and the deformed image with respect to the other image, thereby aligning both images. A radiation tomography apparatus comprising: means. The radiation tomography apparatus according to claim 2,
The radiographic tomography apparatus, wherein the deformed image generating means operates by acquiring movement destination information that is referred to based on distance data indicating a separation distance between a pair of plates output by the movement control means. The radiation tomography apparatus according to claim 6,
A radiation tomography apparatus characterized in that the subject to be deformed is a breast and is used for breast examination.

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