JP2017116326A - Image photographing apparatus for breast examination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographing apparatus for a breast examination, capable of indicating a revolutionary mammary gland density.SOLUTION: According to the present invention, the photographing apparatus for breast examination capable of indicating a revolutionary mammary gland density can be provided. In the present invention, distribution of mammary gland tissues of a subject is recognized on the basis of a distribution of a radiopharmaceutical distributed in the breast and the mammary gland density is calculated. An imaging image of the distribution of the radiopharmaceutical is a kind of a functional image indicating an activity in the subject. Thus, according to the present invention, the mammary gland density can be calculated on the basis of the mammary gland tissues in which the activity is active (active mammary gland tissues).SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image capturing apparatus for breast examination that detects a pair of annihilation radiation emitted from a subject and images a radiopharmaceutical distribution in the subject.

  A medical institution is equipped with a radiation tomography apparatus that images the distribution of a radiopharmaceutical. 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. This detector ring detects a pair of radiations (pairs of annihilation radiations) in opposite directions that are irradiated from a radiopharmaceutical in the subject (see, for example, Patent Document 1). Such an apparatus is called a positron emission tomography apparatus.

  As one type of such a radiation tomography apparatus, there is a radiation tomography apparatus for breast examination. This breast examination image photographing apparatus will be specifically described. FIG. 9 is a diagram for explaining a conventional image examination apparatus for breast examination. In the conventional breast examination image photographing apparatus 51, one side of the breast B of the subject M is introduced into the detector ring 62 during the examination. In this state, the detector ring 62 detects a pair of annihilation radiation irradiated from the subject M.

  The detector ring 62 identifies the source of a pair of annihilation radiations emitted from the breast B, and a radiopharmaceutical distribution is generated based on this position information. Radiopharmaceuticals have the property of accumulating more in cancer tissues than in normal tissues. Therefore, if a radiopharmaceutical distribution map is diagnosed, breast cancer can be screened.

  To image the distribution of the radiopharmaceutical, one of the left and right breasts of the subject is introduced into the detector ring 62. If it is desired to know the distribution of the radiopharmaceutical with respect to the right breast of the subject, the right breast of the subject is introduced into the detector ring 62.

JP2009-074210A

However, the breast examination image capturing apparatus according to the conventional configuration has the following problems.
That is, the breast examination image capturing apparatus according to the conventional configuration cannot sufficiently provide an index relating to the breast.

  A breast examination image capturing apparatus having a conventional configuration cannot provide an index representing the characteristics of the entire breast. A breast examination imaging apparatus is primarily intended for imaging lesions that appear in the breast. Therefore, there is no idea of providing an index that represents the characteristics of the entire breast.

  There is an X-ray mammography apparatus as an apparatus for imaging a breast abnormality. This apparatus is an apparatus that irradiates a breast with X-rays and obtains a morphological image in the breast. When the breast is photographed with such an apparatus, an image in which the internal structure of the whole breast appears slightly is obtained. This image shows the mammary glands present inside the breast. The X-ray mammography apparatus can calculate a mammary gland density which is an index indicating how much the mammary gland is distributed in the breast. The mammary gland density indicates the ratio of the mammary gland to the total breast volume. The index of mammary gland density is not a personality that allows you to judge anything, but it helps you understand the characteristics of the breast. The mammary gland density is information that is additionally obtained in the image diagnosis of the X-ray mammography apparatus, and is currently not obtained by the diagnosis by the image examination apparatus for breast examination.

  The mammary gland density of the X-ray mammography apparatus is calculated by distinguishing mammary gland tissue and adipose tissue by X-ray imaging. How to identify the tissue is determined by whether or not it is easy to transmit X-rays. When calculating mammary gland density as an aid in understanding the characteristics of the breast, there is no guarantee that this uniform way of distinguishing tissues makes sense.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a breast examination imaging apparatus capable of presenting an epoch-making breast density.

The present invention has the following configuration in order to solve the above-described problems.
That is, the imaging apparatus for breast examination according to the present invention is configured such that the radiation detectors for detecting radiation are arranged in an arc shape, and the detector detects the radiation derived from the radiopharmaceutical distributed in the breast of the subject. A three-dimensional image generating means for generating a three-dimensional image showing a radiopharmaceutical distribution in the breast based on an output of the ring and the detector ring, and a pixel value of a predetermined range of each voxel constituting the three-dimensional image Are determined as breast voxels belonging to the breast, and among voxels constituting a three-dimensional image, those having pixel values within a predetermined range are determined as breast voxels located in the mammary gland tissue. It is characterized by comprising discrimination means, and mammary gland density calculating means for calculating mammary gland density based on the number of breast voxels and the number of mammary voxels.

  [Operation / Effect] According to the present invention, it is possible to provide an imaging apparatus for breast examination capable of presenting an epoch-making breast density. That is, in the present invention, the breast density is calculated by recognizing the distribution of the mammary gland tissue of the subject based on the distribution of the radiopharmaceutical distributed in the breast. An imaging image of the distribution of the radiopharmaceutical is a kind of functional image and represents the activity in the subject. Therefore, according to the present invention, the mammary gland density based on active mammary gland tissue (active mammary gland tissue) can be calculated. The mammary gland density obtained by the conventional X-ray imaging is calculated based on the morphological image, and it is visually determined whether the tissue in the breast necessary for the calculation is the mammary gland. Compared with the mammary gland density calculated based on such a determination method, according to the configuration of the present invention, it is possible to calculate the mammary gland density that shows the state of the mammary gland tissue in accordance with the actual situation inside the breast.

  In the breast examination imaging apparatus described above, it is more preferable that the mammary gland density calculating means calculates the mammary gland density by dividing the number of voxels belonging to the breast by the number of mammary voxels.

  [Operation / Effect] With the above-described configuration, the mammary gland density can be calculated more reliably.

  Further, in the above-described breast examination imaging apparatus, tomographic image generation means for generating a tomographic image of a three-dimensional image, and editing for highlighting and displaying each pixel constituting the tomographic image corresponding to a mammary voxel It is more desirable to include a means and a display means for displaying the edited tomographic image.

  [Operation / Effect] With the above-described configuration, the authenticity of the mammary gland density can be confirmed.

  In the above-described breast examination imaging apparatus, it is more desirable to include an input unit for inputting an operator's instruction for changing a range of pixel values used when the determination unit operates.

  [Action / Effect] With the above-described configuration, recognition of the mammary gland tissue can be adjusted.

  In the above-described imaging apparatus for breast examination, it is more desirable if the radiopharmaceutical is a radiolabeled glucose.

  [Operation / Effect] With the above-described configuration, the mammary gland density can be calculated based on the active mammary gland that is more active among the mammary gland tissue.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device for breast examination which can show epoch-making mammary gland density can be provided. That is, in the present invention, the breast density is calculated by recognizing the distribution of the mammary gland tissue of the subject based on the distribution of the radiopharmaceutical distributed in the breast. An imaging image of the distribution of the radiopharmaceutical is a kind of functional image and represents the activity in the subject. Therefore, according to the present invention, the mammary gland density based on active mammary gland tissue (active mammary gland tissue) can be calculated.

1 is a functional block diagram illustrating an overall configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a detector ring according to Embodiment 1. FIG. 1 is a perspective view illustrating a radiation detector according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a three-dimensional image according to Embodiment 1. FIG. FIG. 6 is a schematic diagram for explaining the operation of the active mammary gland extraction unit according to the first embodiment. FIG. 6 is a schematic diagram for explaining the operation of the active mammary gland extraction unit according to the first embodiment. 6 is a schematic diagram illustrating a superimposed image according to Embodiment 1. FIG. It is a schematic diagram explaining the display of the mammary gland density which concerns on Example 1. FIG. It is a schematic diagram explaining the radiation tomography apparatus which concerns on a conventional structure.

  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 an image diagnostic apparatus for breast examination. That is, the radiation tomography apparatus according to the first embodiment performs imaging of a radiopharmaceutical distributed in the breast B to generate a tomographic image. The apparatus according to the first embodiment is configured to individually photograph the right breast and the left breast of the subject M. The radiopharmaceutical used for the breast examination according to the present invention is a radiolabeled glucose. Therefore, the radiation tomography apparatus according to the present invention is configured to image the distribution of glucose metabolism activity in the breast.

<Overall configuration of radiation tomography apparatus>
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 ring-shaped detector ring 12 that introduces the breast B of the subject M from the z direction. The opening provided in the detector ring 12 has a cylindrical shape (more precisely, a regular decagonal prism) extending in the z direction. Therefore, the detector ring 12 itself extends in the z direction. Note that the area of the opening of the detector ring 12 is an imaging field in which a tomographic image of the radiation tomography apparatus 9 can be generated. The z direction is along the direction in which the central axis of the detector ring 12 extends. The detector ring 12 is configured by arranging a later-described radiation detector for detecting radiation in an arc shape. The detector ring 12 is configured by arranging radiation detectors for detecting radiation in an arc shape (annular shape), and detects radiation derived from a radiopharmaceutical distributed in the breast of the subject.

  The top plate 10 is provided for the purpose of placing the subject M in a stomach-like state. The top plate 10 is provided with a hole through which the breast B of the subject M is inserted in the z direction. The breast B is introduced into the detector ring 12 through the hole. The opening of the detector ring 12 is provided vertically upward, and the breast B is introduced into this opening from the vertically downward direction.

  The detector ring 12 is placed on the support base 38. The shielding plate 13 is made of tungsten, lead, or the like (see FIG. 1). Since the radiopharmaceutical is also present in a portion other than the breast B of the subject M, an annihilation γ-ray pair is also generated therefrom. When such an annihilation γ-ray pair generated from a region other than the region of interest enters the detector ring 12, it interferes with tomographic imaging. Therefore, a shielding plate 13 that absorbs γ rays in a ring shape 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 shielding plate 13 is disposed at a position sandwiched between the top plate 10 and the detector ring 12.

  In such a breast examination, FDG (fluorodeoxyglucose) is administered into a subject. This drug has the property of being collected in a portion where glucose metabolism is strong when administered into a subject. Therefore, by imaging the distribution of this FPD, it is possible to know the distribution of glucose metabolism in the breast of the subject.

  The configuration of the detector ring 12 will be described. In the detector ring 12, ten 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 12a. Three unit rings 12a are arranged in the z direction to form the detector ring 12 (specifically, refer to FIG. 2).

  The configuration of the radiation detector 1 will be briefly described. FIG. 3 is a perspective view illustrating the configuration of the radiation detector according to the first embodiment. As shown in FIG. 3, the radiation detector 1 includes a scintillator 2 that converts radiation into light, and a photodetector 3 that includes a photomultiplier tube 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.

  A detection signal output from the detector ring 12 is sent to the coincidence counting unit 21 (see FIG. 1). The two gamma rays simultaneously incident on the detector ring 12 are annihilation gamma ray pairs caused by the radiopharmaceutical in the subject. The coincidence counting unit 21 counts the number of times that an annihilation γ-ray pair is detected for every two combinations of scintillator crystals constituting the detector ring 12, and sends the result to the three-dimensional image generation unit 22. The determination of the coincidence of the detection signal by the coincidence unit 21 uses time information given to the detection signal by a clock.

  The coincidence data output from the coincidence unit 21 is sent to the three-dimensional image generation unit 22. The three-dimensional image generation unit 22 generates a three-dimensional image DR in which the concentration of the radiopharmaceutical is three-dimensionally mapped as shown in FIG. 4 based on the coincidence data. In the three-dimensional image DR, one side of the subject's breast is reflected. The three-dimensional image generation unit 22 generates a three-dimensional image DR showing the radiopharmaceutical distribution in the breast based on the output of the detector ring 12. The three-dimensional image generation unit 22 corresponds to the three-dimensional image generation means of the present invention.

<Characteristic configuration of the present invention>
A feature of the present invention lies in a configuration for calculating the amount of active mammary gland based on the three-dimensional image DR. The active mammary gland will be described. The breast is composed of skin, fat tissue, and mammary tissue. Among these, there are active mammary glands that are actively metabolized and activated by hormones, and non-active mammary glands that have stopped functioning and no longer function. Active mammary glands are active in glucose metabolism and therefore tend to actively incorporate radiopharmaceuticals. On the other hand, inactive mammary glands and adipose tissue are not so active in glucose metabolism and are difficult to incorporate radiopharmaceuticals. In the three-dimensional image DR, the activity of sugar metabolism in the breast is imaged, so that the active mammary gland can be distinguished from other tissues. Such distinction is executed by the active mammary gland extraction unit 23. The active mammary gland extraction unit 23 corresponds to the discrimination means of the present invention.

<Active mammary gland extractor>
The 3D image DR generated by the 3D image generation unit 22 is sent to the active mammary gland extraction unit 23. In the active mammary gland extraction unit 23, three thresholds t1, t2, and t3 as described in FIG. 5 are set. The active mammary gland extraction unit 23 is configured to compare the pixel value of each voxel constituting the three-dimensional image DR with a threshold value and determine what the voxel includes.

  When the pixel value of the voxel is 0 or more and less than the threshold value t1, the voxel captures air. Therefore, when the pixel value of the voxel is equal to or greater than t1, the active mammary gland extraction unit 23 determines that the voxel is imprinting the breast. The active mammary gland extraction unit 23 determines that each voxel constituting the three-dimensional image has a pixel value within a predetermined range as a breast voxel belonging to the breast.

  When the pixel value of the voxel is greater than or equal to t1 and less than the threshold value t2, the voxel represents an adipose tissue or an inactive mammary gland. In addition, when the pixel value of the voxel is equal to or greater than t3, the voxel captures the lesion. The lesion is, for example, cancerous tissue related to breast cancer, and actively performs cell division abnormally. This tissue therefore requires more sugar and incorporates a considerable amount of radiopharmaceutical. Such tissue is clearly not a normal active mammary gland.

  Therefore, the active mammary gland extractor 23 determines that this voxel has captured the active mammary gland when the pixel value of the voxel is equal to or greater than t2 and less than the threshold value t3. The active mammary gland extraction unit 23 determines that each voxel constituting the three-dimensional image has a pixel value within a predetermined range as a mammary gland voxel that is a voxel located in the mammary gland tissue.

  The active mammary gland extraction unit 23 generates an active mammary gland three-dimensional image DM showing the distribution of voxels related to the active mammary gland on the three-dimensional image DR, as shown in FIG.

  Since the active mammary gland three-dimensional image DM can be displayed through the display unit 36, this point will be described. The active breast gland three-dimensional image DM is sent to the active breast tomographic image generation unit 26. On the other hand, the three-dimensional image DR is sent to the tomographic image generation unit 25. The active breast tomographic image generation unit 26 generates an active breast tomographic image that is a tomographic image when the active breast three-dimensional image DM is cut at a certain cross section. Then, the tomographic image generation unit 25 generates a breast tomographic image when the three-dimensional image DR is cut with the same cut surface. The active mammary tomographic image and the breast tomographic image are sent to the overlapping unit 27. The superimposing unit 27 superimposes the active breast tomographic image on the breast tomographic image to generate a superimposed image as shown on the left side of FIG. This superposed image is an image in which an active mammary gland region, which is a region where active mammary glands are distributed, is superimposed on a tomographic image of the breast. This allows the surgeon to know where in the breast the device recognizes that there is an active mammary gland region. This display can be used to confirm the authenticity of the breast density described later. This point will be described later. The superposition part 27 corresponds to the editing means of the present invention. The superimposing unit 27 is configured to perform editing for highlighting the pixels corresponding to the mammary gland voxels among the pixels constituting the tomographic image.

  Note that the surgeon can change where the active breast gland three-dimensional image DM is cut when generating the superimposed image by inputting an instruction through the console 35. With the input of this instruction, the active breast tomographic image generation unit 26 changes the cutting position and regenerates the active breast tomographic image. The tomographic image generation unit 25 regenerates a breast tomographic image in which the cutting position is the same as that of the active breast tomographic image in accordance with this operation. Each regenerated image is sent to the superposition unit 27 and processed into a superposition image, and then displayed on the display unit 36. The console 35 corresponds to the input means of the present invention.

  The operator can also display breast tomographic images up to the superposition process on the display unit 36 on the right side of FIG. 7 by inputting instructions through the console 35. The surgeon can cause the display unit 36 to display a superimposed image as shown on the left side of FIG. 7 through the console 35, or can display a breast tomographic image as shown on the right side of FIG. .

<Breast density calculation unit>
The determination result of the voxels constituting the three-dimensional image DR executed by the active mammary gland extraction unit 23 is sent to the mammary gland density calculation unit 24. The mammary density calculating unit 24 calculates the mammary density D using the number Nb of voxels (mammary voxels) determined by the active mammary gland extracting unit 23 as active mammary tissue and the number Na of voxels (breast voxels) determined to be other than air. To do. Therefore, the number Nb indicates how many voxels whose pixel values are t2 or more and less than the threshold t3 are on the three-dimensional image DR, and the number Na is how many voxels whose pixel values are t1 or more are on the three-dimensional image DR. Is shown. The mammary gland density D is equal to Nb / Na × 100%. The mammary density calculating unit 24 calculates the mammary density by dividing the number of voxels belonging to the breast by the number of breast voxels.

  In addition, this apparatus can confirm where the breast is considered to be a mammary gland and the mammary gland density D is calculated (see FIG. 7). The position of the mammary gland should be distributed near the center of the breast. Therefore, if it is confirmed that the active mammary gland is distributed in the center of the breast in the superimposed image, the mammary gland density D can be evaluated as having high credibility. The mammary gland density calculating unit 24 corresponds to the mammary gland density calculating means of the present invention.

  FIG. 8 shows how the breast density is displayed on the display unit 36. In the case of FIG. 8, imaging of both breasts of the subject has been completed, and breast tomographic images of the right and left breasts are displayed at once. On the display unit 36, the breast density related to the right breast is superimposed on the breast tomographic image related to the right breast, and the breast density related to the left breast is superimposed on the breast tomographic image related to the left breast.

  The main control unit 41 is realized by a CPU, and is configured to execute a program for realizing each of the units 21, 22, 23, 24, 25, 26, and 27. The storage unit 37 stores parameters necessary for the operation of each unit. Moreover, it is good also as a structure provided with the arithmetic unit which replaces with the main-control part 41 and implement | achieves each part separately.

  As described above, according to the present invention, it is possible to provide an imaging apparatus for breast examination that can present an epoch-making breast density. That is, in the present invention, the breast density is calculated by recognizing the distribution of the mammary gland tissue of the subject based on the distribution of the radiopharmaceutical distributed in the breast. An imaging image of the distribution of the radiopharmaceutical is a kind of functional image and represents the activity in the subject. Therefore, according to the present invention, the mammary gland density based on active mammary gland tissue (active mammary gland tissue) can be calculated. The mammary gland density obtained by the conventional X-ray imaging is calculated based on the morphological image, and it is visually determined whether the tissue in the breast necessary for the calculation is the mammary gland. Compared with the mammary gland density calculated based on such a determination method, according to the configuration of the present invention, it is possible to calculate the mammary gland density that shows the state of the mammary gland tissue in accordance with the actual situation inside the breast.

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

  (1) The operator 35 may be configured to input an operator's instruction regarding a change in the pixel value range used when the active mammary gland extraction unit 23 operates. According to this configuration, the above-described threshold values t1, t2, and t3 can be changed according to the operator's intention.

  (2) Although the detector ring 12 according to the first embodiment has an annular shape, the present invention is not limited to this configuration. The detector ring 12 can also be configured in an arc shape.

12 detector ring 22 3D image generation unit (3D image generation means)
23 Active mammary gland extraction unit (discrimination means)
24 Breast density calculation unit (breast density calculation means)

Claims (5)

A detector ring configured to detect radiation derived from a radiopharmaceutical distributed in a breast of a subject, and configured to include radiation detectors configured to detect radiation;
Three-dimensional image generation means for generating a three-dimensional image showing the radiopharmaceutical distribution in the breast based on the output of the detector ring;
Among the voxels constituting the three-dimensional image, those having pixel values within a predetermined range are determined as breast voxels belonging to the breast, and the pixel values of the voxels constituting the three-dimensional image are predetermined. A discriminating means for discriminating a mammary gland voxel that is a voxel located in mammary gland tissue,
An imaging apparatus for breast examination, comprising: mammary gland density calculating means for calculating mammary gland density based on the number of breast voxels and the number of mammary voxels. The imaging device for breast examination according to claim 1,
The breast examination imaging device, wherein the breast density calculating means calculates the breast density by dividing the number of the mammary voxels by the number of the breast voxels. In the imaging apparatus for breast examination according to claim 1 or 2,
A tomographic image generating means for generating a tomographic image of the three-dimensional image;
An editing unit that performs editing for highlighting one corresponding to the mammary gland voxel among the pixels constituting the tomographic image;
An imaging device for breast examination, comprising: display means for displaying the tomographic image after editing. In the imaging device for breast examination in any one of Claims 1 thru | or 3,
An imaging device for breast examination, comprising: an input unit for inputting an operator's instruction for changing a range of pixel values used when the determination unit operates. In the imaging device for breast examination in any one of Claims 1 thru | or 4,
An imaging apparatus for breast examination, wherein the radiopharmaceutical is a radiolabeled glucose.

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