JP6271962B2 - Breast tomography equipment - Google Patents

Description

  The present invention relates to a tomography apparatus that performs computed tomography (CT imaging), and more particularly to a mammography tomography apparatus (mammo CT apparatus) used for imaging a breast.

  Conventionally, breast cancer examinations have been performed using palpation and ultrasonic diagnosis, but mammo CT apparatuses capable of performing mammography using three-dimensional (3D) images using CT imaging have been developed.

  Patent Document 1 discloses an example of a mammo CT apparatus. The mammo CT apparatus disclosed in Patent Document 1 includes a top plate with an open / closed breast entrance, a measurement device that rotates horizontally around the breast entrance / exit, an X-ray generator, and a radiation detector. Has been. At the time of CT imaging, the subject lies down on the top and shoots while the breast is inserted into the breast storage part from the breast entrance / exit. Imaging is performed at each predetermined angular position while the X-ray generator and the radiation detector with a built-in collimator for defining the X-ray irradiation area rotate around the rotation axis passing through the breast housing, and viewed from each direction. An X-ray transmission image of the subject is acquired. Further, an X-ray shielding plate for blocking leakage of X-rays to the human body is attached to the lower surface of the top plate.

US Pat. No. 6,987,831

  In a mammo CT apparatus such as that disclosed in Patent Document 1, a breast is inserted into a breast storage unit from a breast entrance / exit while applying the subject's sternum to the upper surface of the top plate. As a result, the breast overlaps within the X-ray irradiation area irradiated to the breast storage section, so that an X-ray transmission image can be projected and photographed on the radiation detector. In the mammo CT apparatus described above, it is necessary to bring the X-ray irradiation area closer to the top plate side so that the breast on the sternum side (root portion) can be imaged as much as possible.

  On the other hand, leakage of X-rays from the aforementioned X-ray irradiation area to the subject side must be prevented. The X-ray generator in Patent Document 1 has a configuration in which a collimator that defines an X-ray irradiation area is integrally incorporated in the vicinity of the focal point of the X-ray generator. However, since the collimator built in the X-ray generator exists at a position away from the radiation detector, X-ray semi-shadows are generated in a wide area outside the X-ray irradiation region. For this reason, there is a problem that only the collimator built in the X-ray generator leads to leakage of X-rays to the subject.

  By providing a collimator with an X-ray shield that defines the X-ray transmission part as an opening at a position close to the radiation detector, the X-ray irradiation area is defined while suppressing the occurrence of the above-described half-shade, and the subject It is conceivable to prevent leakage of X-rays.

  Incidentally, in order to bring the X-ray irradiation region closer to the top plate side, it is necessary to bring the collimator closer to the top plate side. However, in order to prevent leakage of X-rays from the top plate, it interferes with the X-ray shield disposed inside the top plate, so that the collimator cannot be brought closer to the top plate side beyond a certain amount.

  Accordingly, an object of the present invention is to prevent the leakage of radiation to the subject side in the mammo CT apparatus using radiation typified by X-rays, and the breast by exerting the radiation irradiation region to the breast root of the subject. The purpose is to make radiation imaging up to the root compatible.

The present invention includes a gantry having for this purpose, the front plate having a breast insertion opening is provided to the breast is inserted, a breast insertion portion continuous to the breast insertion opening, and
Is arranged on the inner part of the gantry, and the X-ray generation tube having an X-ray emitting section,
Is arranged on the inner part of the gantry, and the X-ray detector facing the X-ray emitting section between the breast insertion portion,
About the axis of rotation passing through the breast insertion portion, anda rotary drive unit for rotating in synchronization with the X-ray generating tube and the X-ray detector,
A breast tomography apparatus that irradiates X- rays from the X- ray emission part to the X- ray detector via the breast insertion part ,
Said breast insertion opening X-ray shielding section of annular provided in the front plate surrounds the periphery of, in between said breast insertion portion and the X-ray emitting portion, the X-ray generating tube about said rotary shaft anda collimator which rotates in synchronism with,
The collimator is to provide a breast tomography apparatus characterized by in the radial direction perpendicular to the rotating shaft has a portion overlapping with the X-ray shielding portion.

  According to the present invention, by providing a collimator between the breast storage part and the radiation emitting part of the radiation generating tube, the position of the collimator can be brought close to the radiation detector, and half of the radiation spreading outside the radiation irradiation region can be obtained. Shadows can be suppressed. In addition, since an annular radiation shield is provided at least on the inner surface of the front plate on the side of the rotation path of the radiation emitting unit relative to the rotation path of the collimator, the scattered radiation generated when the radiation irradiation area is regulated by the collimator It is possible to prevent leakage to the side. And the leakage amount of the radiation to a test subject side can be suppressed by these.

  On the other hand, in the present invention, in the collimator rotation path, the end of the collimator facing the front plate enters the front plate side from the surface of the radiation shield. That is, even when compared with the case where a collimator is provided in contact with the radiation shield, the collimator can be brought closer to the front plate by the thickness of the radiation shield, and the radiation irradiation region can be brought closer to the front plate. Thus, radiation imaging up to the breast root by applying the radiation irradiation area to the breast root of the subject can be performed. In addition, it is possible to make it difficult for the scattered radiation generated when the radiation is regulated by the collimator to leak to the subject side.

It is a whole perspective view of a mammography apparatus (mammo CT apparatus). It is sectional drawing of the mammo CT apparatus of the 1st example of this invention, (a) is sectional drawing seen from the X direction in FIG. 1, (b) is sectional drawing seen from the Y direction in FIG. FIG. 3 is an enlarged view around the collimator from the radiation generating tube in FIG. It is a block diagram of the imaging | photography system of the mammo CT apparatus of this invention. It is sectional drawing of the mammo CT apparatus of the 2nd example of this invention, (a) is sectional drawing seen from the X direction in FIG. 1, (b) is sectional drawing seen from the Y direction in FIG. It is sectional drawing of the mammo CT apparatus of the 3rd example of this invention, (a) is sectional drawing seen from the X direction in FIG. 1, (b) is sectional drawing seen from the Y direction in FIG. It is an expansion perspective view of the collimator in the 3rd example of the present invention. It is sectional drawing of the mammo CT apparatus of the 4th example of this invention, (a) is sectional drawing seen from the X direction in FIG. 1, (b) It is sectional drawing seen from the Y direction. FIG. 5 is a cross-sectional view of a mammo CT apparatus according to a fourth example of the present invention, in which (a) is a cross-sectional view seen from the X direction in FIG. 1 and (b) is a cross-sectional view seen from the Y direction in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings referred to below, the same reference numerals indicate the same components.

[First example]
<Outline of mammo CT system>
As shown in FIGS. 1 to 3, a mammography tomography apparatus (mammography CT apparatus) 1 has a gantry 2 that constitutes a room in which a radiation source, a collimator 12, and the like are housed. In addition, a breast storage part 3 for the subject P to insert the breast 15 is provided at the center of the gantry 2. In addition, 4 is a support part.

  The gantry 2 includes an inner peripheral plate 5 that surrounds the breast storage unit 3, an outer peripheral plate 6 that surrounds the outer periphery, a front plate 7 that connects the inner peripheral plate 5 and the outer peripheral plate 6 on the front side, and a back side that is not shown. It is a hollow disk-shaped member which has a back plate. In the front plate 7, a breast entrance / exit 17 for entering / exiting the breast 15 to / from the breast storage unit 3 is opened. Inside the gantry 2, a radiation generating tube 8, a radiation detector 11, and a collimator to be described later are supported by a rotating plate (not shown). During CT imaging, a rotation driving unit 101 (see FIG. 4). It is configured to rotate as a tripartite. This rotation is performed around a rotation axis D that passes through the inside of the breast storage unit 3 and extends in the direction in which the breast 15 enters and exits the breast storage unit 3 (Z direction). The radiation generating tube 8, the radiation detector 11, and the collimator 12 are rotated at the same angular velocity. At the time of radiography with the mammo CT apparatus 1, the subject P inserts the breast 15 from the front side 7 of the front plate 7 of the gantry 2 through the breast entrance / exit 17 into the breast housing 3 and performs CT radiography while maintaining this posture. Do. The mammo CT apparatus 1 of this example is of a type in which the front plate 7 is installed vertically and the subject P stands in front of the front plate 7 for examination. However, the mammo CT apparatus 1 according to the present invention is a type in which the front plate 7 is placed sideways and the front plate 7 is a top plate described in the background art, and the subject lies on the front plate 7 and is inspected. It can also be. In this case, the inner peripheral plate 5 can be omitted.

<Radiation tube>
As shown in FIGS. 2 and 3, the radiation generating tube 8 is a transmissive radiation generating tube, and includes an electron gun 9 that generates an electron beam and a radiation emitting unit 10. As the electron gun 9, for example, a hot filament type electron generation source can be used. The radiation emitting unit 10 includes a transmission type target in which a target layer that generates radiation by irradiating an electron beam from an electron gun 9 is laminated on a radiation transmissive support substrate. The material constituting the support substrate is preferably a material having a strength capable of supporting the target layer, a low absorption of radiation generated in the target layer, and a high thermal conductivity so that heat generated in the target layer can be quickly dissipated. For example, diamond, silicon carbide, aluminum nitride, or the like can be used. The material constituting the target layer is preferably a material having a high melting point and high radiation generation efficiency. For example, tungsten, tantalum, molybdenum and alloys thereof can be used. The radiation generating tube 8 is supported by a rotating plate (not shown) that is rotated by a rotation driving unit 101 (see FIG. 4). It rotates around D.

<Radiation detector>
The radiation detector 11 is provided at a position facing the radiation emitting portion 10 of the radiation generating tube 8 with the breast accommodating portion 3 interposed therebetween. The sensor area of the radiation detector 11 in this example is usually a size that coincides with a radiation irradiation region 13 defined by a collimator 12 or the like described later. The shape of the sensor area in this example is a square according to the shape of the radiation irradiation region 13. The radiation detector 11 is supported by a rotating plate (not shown) that is rotated together with the radiation generating tube 8 by a rotation driving unit 101 (see FIG. 4). The radiation detector 11 rotates in the same direction at the same angular velocity as that of the radiation generating tube 8 around the rotation axis D extending in the direction in which the breast 15 enters and exits the breast housing 3 by the rotation of the rotating plate. .

<Collimator>
As shown in FIGS. 2 and 3, an irradiation region 13 of the radiation emitted from the radiation emitting unit 10 of the radiation generating tube 8 is provided at an intermediate position between the radiation emitting unit 10 of the radiation generating tube 8 and the breast storage unit 3. A collimator 12 to be defined is arranged. The collimator 12 is supported by a rotating plate (not shown) that supports the radiation generating tube 8 and the radiation detector 11, and rotates in the same direction in synchronization with the radiation generating tube 8 and the radiation detector 11 during CT imaging. .

  Radiation generated in the target layer of the transmissive target is transmitted to the outside through the target layer and the support substrate holding the target layer. The emission range of the radiation emitted from the radiation emitting portion 10 of the radiation generating tube 8 is regulated by a front shield (not shown) provided in the radiation emitting portion 10 of the radiation generating tube 8. The radiation irradiation region 13 is further defined by a collimator 12 provided between the radiation emitting unit 10 and the breast storage unit 3.

  The radiation is irradiated toward the radiation detector 11, and the radiation irradiation region 13 is defined by the radiation transmitting portion defined by the collimator 12 so as to be substantially square on the detector 11. To reach. At this time, when the breast 15 of the subject P enters the radiation irradiation region 13, a radiation transmission image of the breast 15 reaches the radiation detector 11, and a transmission image of the mammary gland and fat contained in the breast 15. Is obtained. As the material of the collimator 12, heavy metals such as lead, tungsten, tantalum, and rhenium having radiation shielding ability are suitable.

  In the present invention, the collimator 12 is a radiation shielding material that blocks a part of the radiation emitted from the radiation emitting portion 10 of the radiation generating tube 8 and regulates a part or the whole circumference of the radiation irradiation region 13. Refers to the configured member. The collimator 12 can be formed of a frame material made of a radiation shielding material that defines a radiation transmitting portion as an opening. If the collimator 12 is a plane U-shaped, U-shaped or N-shaped frame material in which the front surface 7 side of the radiation transmitting portion is open, the radiation irradiation region 13 can be easily brought closer to the front plate 7 side. In the case of the flat square collimator 12 in which the entire circumference of the radiation transmitting portion is surrounded by a frame material of radiation shielding material, it is easy to block leakage of excess radiation to the front plate 7 side. Further, since the collimator 12 is separate from the radiation generating tube 8 and can be disposed close to the breast accommodating portion 3, it is separated from the breast accommodating portion 3 as in the case of a collimator integrated with the radiation generating tube 8. It is possible to reduce a semi-shade that is likely to occur when collimating at a position.

<Radiation shield>
As shown in FIGS. 2 and 3, a plate-shaped radiation shield 14 is provided inside the front plate 7 of the gantry 2 so as to surround the periphery of the breast entrance / exit 17. The radiation shield 14 is disposed along the front plate 7 between the rotation path of the collimator 12 and the rotation path of the radiation emitting unit 10 accompanying the rotation of the radiation generating tube 8, and isolates the radiation irradiation region 13 and the subject P. It is provided to do. The radiation shield 14 has an annular shape in which a central portion corresponding to the breast entrance / exit 17 and the breast accommodating portion 3 connected thereto is punched out. The radiation shield 14 directly leaks radiation from the radiation emitting portion 10 of the radiation generating tube 8 to the subject P, and scattered radiation generated when the collimator 12 is exposed to radiation leaks to the subject P. It is for preventing. As the material of the radiation shield 14, heavy metals such as lead, tungsten, tantalum, and rhenium having high radiation shielding ability are suitable. The radiation shield 14 is generally annular, but may be elliptical or rectangular.

  By arranging the radiation shield 14 on the inner surface of the front plate 7 closer to the rotation path of the radiation emitting unit 10 than the rotation path of the collimator 12, it is possible to prevent the subject P from being irradiated with excess radiation. Specifically, it is possible to prevent leakage of the radiation directly irradiated to the subject P from the radiation generating tube 8 and the scattered radiation generated when the collimator 12 is irradiated with radiation to the subject P. . The radiation shield 14 preferably covers the entire inner surface of the front plate 7 closer to the rotation path of the radiation emitting unit 10 than the rotation path of the collimator 12.

  The radiation shield 14 in this example is provided with a gap 14c between the breast entrance / exit 17 and the collimator 12 is provided at a position corresponding to the gap 14c. Further, as shown in FIG. 3, the end of the collimator 12 on the side facing the front plate 7 enters the side of the front plate 7 from the surface of the radiation shield 14 over the entire rotation path of the collimator 12. . That is, the end of the collimator 12 on the side facing the front plate 7 enters the inside of the gap 14c. With such an arrangement, when viewed from the Z direction, the end of the collimator 12 on the side facing the front plate 7 is in a state of entering the thickness of the radiation shield 14. For this reason, the collimator 12 can be brought close to the front plate 7 of the gantry 2 without being obstructed by the radiation shield 14, and the radiation irradiation region 13 can be brought close to the front plate 7 to extend to the root of the breast 15. CT imaging becomes possible. Further, as described above, the end of the collimator 12 on the side facing the front plate 7 overlaps with the thickness of the radiation shield 14, so that radiation from between the collimator 12 and the radiation shield 14 is not affected. Leakage can also be suppressed.

  In the present embodiment, the end of the collimator 12 on the side facing the front plate 7 is arranged so as to enter the front plate 7 side from the surface of the radiation shield 14 over the entire rotation path of the collimator 12. However, the present invention is not limited to this. In the present invention, the end of the collimator 12 on the side facing the front plate 7 may be arranged so as to enter the front plate 7 side from the surface of the radiation shield 14 at least in the rotation path of the collimator 12. For example, when the collimator 12, the radiation generating tube 8, and the radiation detector 11 have a rotation path for performing preliminary rotation outside the period of the exposure operation, the preliminary rotation path is not necessarily described above. It is not necessary to take this arrangement.

<Mammo CT system imaging system>
FIG. 4 is a configuration diagram of an imaging system of the mammo CT apparatus of the present invention.

  The system control apparatus 100 controls the radiation generating apparatus 103 including the radiation generating tube 8 and its driving circuit 102, the radiation detector 11, and the rotation driving unit 101 in cooperation with each other. The drive circuit 102 outputs various control signals to the radiation generating tube 8 under the control of the system control device 100. The rotation driving unit 101 uses the position information from the position detection sensor 104 for detecting the position of the rotating body that supports the radiation generating tube 8 and the like, and a rotating plate (not shown) under the control of the system control device 100. A drive control signal for driving a predetermined amount is output. The emission state of the radiation emitted from the radiation generator 103 is controlled by rotating the rotation driving unit 101 by a predetermined amount by the control signal described above. The radiation emitted from the radiation generator 103 is partially shielded by the collimator 12 or the like, passes through the breast 15 and is detected by the radiation detector 11. The radiation detector 11 converts the detected radiation into an image signal and outputs it to the signal processing unit 105. The signal processing unit 105 performs predetermined signal processing on the image signal under the control of the system control device 100, and the processed image signal is photographed at each rotational position by the image processing unit 106 in the system control device 100. A CT image is generated from the obtained image information. A three-dimensional image is generated by synthesizing a plurality of CT images obtained by rotating the radiation generating tube 8 around the breast storage unit 3 in FIG. 2 by the image synthesizing unit, and the three-dimensional image is displayed on the screen by the display unit. Can be displayed.

[Second example]
FIG. 5 shows a mammo CT apparatus according to the second example. In this example, the annular radiation shield 14 with the center portion punched out is an inner radiation shield 14 b on the breast entrance / exit 17 side and an outer radiation shield on the rotation path side of the radiation emitting portion 10 of the radiation generating tube 8. It is divided into the body 14a and provided with a gap 14c between them. The collimator 12 is provided at a position corresponding to the gap 14c, and the end of the collimator 12 on the side facing the front plate 7 extends from the surface of the outer peripheral radiation shield 14a over the entire rotation path of the collimator 12. It enters the front plate 7 side. In other words, the end of the collimator 12 on the side facing the front plate 7 enters the gap 14c. Except for these points, the second example is the same as the first example.

  With the configuration as described above, the radiation irradiation region 13 can be obtained by bringing the collimator 12 closer to the front plate 7 of the gantry 2 while suppressing the leakage of radiation to the subject P as in the first example. Close to the front plate 7 and a wide range of CT imaging up to the root of the breast 15 is possible. Also. By laying out the collimator 12 on the radiation generating tube 8 side, the collimator 12 can be made small and light.

[Third example]
As shown in FIGS. 6 and 7, the collimator 12 of this example has a three-dimensionally curved shape. Specifically, in the direction of the rotation radius around the rotation axis D shown in FIG. The rest is the same as the first example described above.

  By doing in this way, the width | variety of the clearance gap 14c opened between the breast entrance / exit 17 and the radiation shielding member 14 can be made small, and the leakage of the radiation from this area | region can be suppressed. It is most preferable that the center of curvature of the collimator 12 coincides with the rotation axis D because the width of the gap 14c can be made the smallest.

[Fourth example]
As shown in FIG. 8, it is the same as the second example described above except that the curved collimator 12 is the same as the third example.

  By doing in this way, it can be set as the mammo CT apparatus which has the advantage of a 2nd example and a 3rd example.

[Fifth example]
As shown in FIG. 9, as in the third example, the radiation shield 14 is provided with a gap 14c between the breast entrance and exit 17, and the curved collimator 12 is placed in the gap 14c. It is provided at the corresponding position. Further, the radiation detector 11 is provided adjacent to the gap 14c, and at least the gap 14c adjacent to the radiation detector 11 is filled, and the periphery of the rotation axis D is synchronized with the radiation detector 11 in the same manner. A radiation sub-shield 16 that rotates in the direction is provided.

  If such a radiation sub-shield 16 is provided, it is possible to prevent the scattered radiation generated when the radiation detector 11 is irradiated with radiation from leaking from the gap 14 c adjacent to the radiation detector 11. be able to. The radiation sub-shield 16 can be made of the same material as the radiation shield 14.

  In order to maximize the above effect, it is most preferable that the center of curvature of the collimator 12 coincides with the rotation axis D, and the center of curvature of the radiation sub-shielding body 16 coincides with the rotation axis D. In this example, the radiation auxiliary shield 16 is applied to the third example. However, the radiation auxiliary shield 16 is applied to the fourth example, or the collimator 12 is not curved. It can also be applied to the example and the second example.

  1: mammography apparatus (mammography CT apparatus), 2: gantry, 3: breast housing part, 4: support part, 5: inner peripheral plate, 6: outer peripheral plate, 7: front plate, 8: radiation generating tube, 9 : Electron gun, 10: radiation emitting part, 11: radiation detector, 12: collimator, 13: radiation irradiation region, 14: radiation shield, 14a: outer radiation shield, 14b: inner radiation shield, 14c: gap , 15: breast, 16: radiation auxiliary shield, 100: system controller, 101: rotation drive unit, 102: drive circuit, 103: radiation generator, 104: position detection sensor, 105: signal processing unit, 106: image Processing unit 107: Rotation drive control unit 108: Radiation generation tube control unit 109: Image storage unit 110: Image composition unit 111: Display unit P: Subject D: Rotation axis

Claims (13)

A gantry having a front plate breast insertion opening is provided to the breast is inserted, a breast insertion portion continuous to the breast insertion opening, and
Is arranged on the inner part of the gantry, and the X-ray generation tube having an X-ray emitting section,
Is arranged on the inner part of the gantry, and the X-ray detector facing the X-ray emitting section between the breast insertion portion,
About the axis of rotation passing through the breast insertion portion, anda rotary drive unit for rotating in synchronization with the X-ray generating tube and the X-ray detector,
A breast tomography apparatus that irradiates X- rays from the X- ray emission part to the X- ray detector via the breast insertion part ,
Said breast insertion opening X-ray shielding section of annular provided in the front plate surrounds the periphery of, in between said breast insertion portion and the X-ray emitting portion, the X-ray generating tube about said rotary shaft anda collimator which rotates in synchronism with,
The breast tomography apparatus according to claim 1, wherein the collimator has a portion that overlaps the X-ray shielding portion in a radial direction orthogonal to the rotation axis . The collimator data, the over rotation path, breast tomography apparatus according to claim 1, characterized in that it has a portion that overlaps with the X-ray shielding portion. The said X-ray shielding part has a thick part which has thickness in the said rotating shaft direction, and has a part which overlaps with the said collimator in the said thick part, The Claim 1 or 2 characterized by the above-mentioned. Breast tomography equipment. The X-ray blocking portion is positioned through the breast insertion opening and the gap, in said gap, one of claims 1 to 3 wherein the collimator is characterized overlap to Rukoto and the X-ray blocking portion The breast tomography apparatus according to one item . The X-ray shielding section, and the inner circumferential X-ray shielding portions of the side of the breast insertion opening, and an outer peripheral X-ray shielding section of the rotational path side of the X-ray emitting portion, a gap is provided between them, in said gap, said collimator breast tomography apparatus according to any one of claims 1 to 3, wherein said X-ray shielding portions overlap to Rukoto. The X-ray detector enters the gap, to claim 4 or 5, characterized in that it has an X-ray sub-shielding unit that rotates around the rotational axis synchronously with the X-ray detector in the same direction breast tomography apparatus as claimed. The breast tomography apparatus according to claim 6, wherein the X-ray sub-shielding unit is located on the opposite side of the collimator with the breast insertion opening interposed therebetween. The tomography apparatus according to any one of claims 1 to 3, wherein the X-ray shielding unit has a portion overlapping before the collimator when viewed from the X-ray emission unit. The breast tomography apparatus according to any one of claims 1 to 3, wherein the collimator has a portion that overlaps in front of the X-ray shielding unit when viewed from the X-ray emission unit. . 10. The breast tomography apparatus according to claim 1, wherein the collimator overlaps the X-ray shielding portion at an end portion on a side facing the front plate. The collimator, breast tomography apparatus according to any one of claims 1 to 10, characterized in that curved convexly outwardly in the radial direction. The breast tomography apparatus according to claim 11 , wherein the center of curvature of the collimator is positioned so as to overlap the rotation axis. The collimator, breast tomography apparatus according to any one of claims 1 to 12, characterized in that the side of the front plate is opened.

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