JP2016221156A - Radiation therapy apparatus calibration phantom and radiation therapy apparatus positioning method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation therapy apparatus calibration phantom that enables a positional deviation of a movable shaft in a radiation therapy apparatus to be determined accurately, and can be applied to the positioning with a criterion of a building and to the positioning with a plurality of apparatuses.SOLUTION: A radiation therapy apparatus calibration phantom includes a rectangular parallelepiped-shaped rectangular parallelepiped member, each surface of which is formed of a plate member made of a material that transmits visible light. Some or all of the surfaces of the rectangular parallelepiped member are provided with grooves and holes. The grooves are embedded with metal wires, and the holes are embedded with metal balls. Acrylate resin is used for the plate member constituting the rectangular parallelepiped member. Piano wires are used for the metal wires that the grooves are embedded with, and stainless steel balls are used for the metal balls.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a radiotherapy apparatus calibration phantom and a radiotherapy apparatus alignment method using the same.

  In recent years, radiation treatment aiming at healing is widely performed by irradiating a lesion part such as a cancer or a tumor to destroy tissue cells of the lesion part or prevent division. Here, the term “radiation” refers to particle radiation consisting of material particles (ion (helium ions, carbon ions, neon ions, silicon ions, argon ions, etc.), electrons, neutrons, protons, mesons, etc.) that flow with high kinetic energy. And electromagnetic radiation consisting of high-energy electromagnetic waves (gamma rays, X-rays, etc.).

  Such a radiotherapy apparatus includes a radiation source that generates radiation, and a medical linac (hereinafter also referred to as a gantry) having a diaphragm device that narrows down the radiation from the radiation source.

  When performing radiotherapy using this radiotherapy apparatus, the above lesion is irradiated with a dose of radiation necessary for obtaining a sufficient therapeutic effect, and other normal tissues other than the lesion are applied. It is desirable to satisfy the condition that radiation exceeding the allowable dose for normal tissue is not performed as much as possible so that no damage occurs.

  For this reason, before starting radiotherapy, the position, size, shape, number, etc. of the lesions are accurately specified, and the region (irradiation field), the irradiation angle, and the irradiation gate to which radiation is irradiated based on this identification result The radiation treatment plan is determined by determining the number and the like so that the radiation concentrates on the lesion and the dose distribution around the lesion is appropriate.

  When the irradiation center (isocenter) of the radiation in the radiotherapy apparatus is deviated, even if the above-described radiotherapy plan is correct, as a result, the radiation is not irradiated at the desired position, and the lesion cannot be accurately irradiated. Particularly in recent years, an irradiation method using an advanced technique has been established, and the radiotherapy apparatus is precisely adjusted. Since the radiotherapy apparatus has a plurality of movable axes, the position of the irradiation center is accurately adjusted by accurately adjusting the positions of these movable axes. In some cases, it is recommended that these adjustments be made before the start of treatment every day. However, since the inspection takes time, the burden on the radiologist is increasing.

  In view of this, there has been proposed a radiation therapy apparatus calibration phantom (hereinafter also simply referred to as a phantom) that can determine the displacement of the movable axis of the radiation therapy apparatus. This phantom includes a rectangular parallelepiped member having a rectangular parallelepiped shape formed of a material capable of transmitting radiation, and a shielding portion that partially shields radiation on the rectangular parallelepiped member, and the shielding portion includes three members orthogonal to each other. Have. Since this phantom is composed of only members whose shielding portions are orthogonal to each other, it is difficult to calibrate a total of six axes including three translation axes and three rotation axes.

  Conventionally, since it is not necessary to align the building reference of the place of installation of the radiation therapy apparatus and the phantom, the use of an optical measurement unit has been unnecessary. However, a system including a radiation therapy apparatus using particle radiation includes a plurality of apparatuses such as a particle radiation apparatus and an X-ray imaging apparatus. For this reason, it is desired to align the positions of a plurality of devices. That is, it is desired to match the building standard and the position of the phantom.

JP 2010-178899 A

  This embodiment can accurately determine the displacement of the movable shaft of the radiotherapy apparatus, and can be applied to alignment with a building reference and alignment with a plurality of apparatuses. And the positioning method of the radiotherapy apparatus using the same is provided.

  The radiation therapy apparatus calibration phantom according to the present embodiment has a rectangular parallelepiped shape made of a material that has first and second surfaces facing each other and third and fourth surfaces facing each other and is capable of transmitting visible light. A structural member; first and second metal wires provided on the first surface and arranged in a cross shape; a first metal ball and the first metal provided at one end of the first metal wire; A second metal sphere provided at the other end of the wire, and third and fourth metal wires provided on the second surface and arranged in a cross shape with each other, the second surface being the first surface The third metal line overlaps at least partly with the second metal line and the fourth metal line overlaps at least partly with the first metal line when parallel projected onto the third metal line; , A third metal ball provided at one end of the third metal wire and the front A fourth metal sphere provided at the other end of the third metal line; fifth and sixth metal lines provided on the third surface and arranged in a cross shape; one of the fifth metal lines; A fifth metal sphere provided at the end and a sixth metal sphere provided at the other end of the fifth metal line, and seventh and eighth provided on the fourth surface and arranged in a cross shape. When the fourth surface is projected in parallel to the third surface, the seventh metal line at least partially overlaps the sixth metal line and the eighth metal line is the fifth metal line. The seventh and eighth metal wires at least partially overlap with each other, a seventh metal ball provided at one end of the seventh metal wire, and a first metal ball provided at the other end of the seventh metal wire. 8 metal balls.

The perspective view which shows the phantom for radiotherapy apparatus calibration of one Embodiment. Sectional drawing which shows the embedding part of the metal wire in the phantom for radiotherapy apparatus calibration by one Embodiment. Sectional drawing which shows the embedding part of the metal sphere in the phantom for radiotherapy apparatus calibration by one Embodiment. The figure explaining alignment with a building reference | standard and the radiation therapy apparatus calibration phantom. The figure explaining position alignment with an X-ray imaging device and a radiation therapy apparatus calibration phantom. The figure explaining position alignment with a treatment beam radiation apparatus and a radiation treatment apparatus calibration phantom. The figure explaining alignment with a treatment table and a radiation therapy apparatus calibration phantom. The figure which shows the relationship between a reference point coordinate and the coordinate in which the translational shift generate | occur | produced. The figure which shows the relationship between a reference point coordinate and the coordinate which the rotation gap | deviation produced.

  Embodiments of the present invention will be described below with reference to the drawings.

(One embodiment)
A perspective view of an example of a radiation therapy apparatus calibration phantom (hereinafter also simply referred to as a phantom) according to an embodiment is shown in FIG. The phantom 1 of this embodiment has a rectangular parallelepiped member, and each surface of the rectangular member is formed of a plate member made of a material that transmits visible light. Grooves and holes are provided in some or all surfaces of the rectangular parallelepiped member. A metal wire is embedded in these grooves, and a metal sphere is embedded in the hole. For example, as the plate member constituting the rectangular parallelepiped member, for example, PMMA (polymethylmethacrylate), that is, an acrylic resin in a broad sense is used. Moreover, for example, a piano wire is used as the metal wire embedded in the groove, and a stainless steel ball is used as the metal sphere. As shown in FIG. 2A, the metal wire 4 is embedded in the groove 2 a provided in the plate member 2. Further, as shown in FIG. 2B, the metal ball 5 is embedded in a hole 2 b provided in the plate member 2. After the metal sphere 5 is embedded in the hole 2b, the upper part of the hole 2b is plugged with a member 2c made of PMMA. In FIGS. 2A and 2B, the plate member is irradiated with radiation from the upper surface.

  The metal spheres are provided on at least two opposing surfaces and at least two metal balls are disposed on each surface. These metal spheres have a straight line connecting at least two metal spheres provided on one surface when one surface of a pair of opposing surfaces is projected in parallel on the other surface. It arrange | positions so that it may orthogonally cross the straight line which ties at least 2 metal ball provided in the surface. As described above, each metal sphere is provided close to the surface of the plate member opposite to the surface irradiated with radiation.

  The metal lines are respectively provided on at least two opposing surfaces. These metal wires are arranged in a cross shape on each surface. The metal lines are arranged such that when one surface of a pair of opposing surfaces is projected in parallel on the other surface, the cross-shaped intersection points coincide with each other and the intersection point is located at the center of each surface. The Further, on each surface, the metal wires are provided so as to have different lengths or have a structure separated in the middle. The length of each metal wire is a predetermined value.

For example, as shown in FIG. 1, metal wires 4 a _{1 to} 4 a ₈ embedded in eight grooves and metal spheres embedded in three holes are formed on the upper surface 3 a of the upper and lower surfaces facing each other. and 5a ₁ to 5 a ₃ is provided. On the lower surface 3b of the opposing upper and lower surfaces, and five each groove embedded metal wire _4b 1 _{~4b 5,} respectively the metal balls _5b 1 _{~5b 2} embedded in two holes, is provided It has been.

Among the metal wires 4a _{1 to} 4a ₈ provided on the upper surface 3a, the metal wires 4a _{1 to} 4a ₃ are the first straight line on the upper surface 3a extending from the far side to the near side, for example, the left side of the upper surface 3a with respect to the center line The metal wires 4a _{4 to} 4a ₆ are arranged on the right side of the upper surface 3a with respect to the first straight line. The metal wires 4a ₇ and 4a ₈ are arranged on the first straight line.

The metal wire 4a ₁ and the metal wire 4a ₂ are arranged in parallel, and the metal wire 4a ₃ is arranged between the metal wire 4a ₁ and the metal wire 4a ₂ so as to be parallel to each other. The metal wire 4a ₄ and the metal wire 4a ₅ are arranged in parallel, and the metal wire 4a ₆ is arranged between the metal wire 4a ₄ and the metal wire 4a ₅ so as to be parallel to each other. Further, the metal line 4a ₁ and the metal line 4a ₄ are located on the second straight line, the metal line 4a ₂ and the metal line 4a ₅ are located on the third straight line, and the metal line 4a ₃ and the metal line 4a ₆ are the fourth line. Located on a straight line. The first straight lines on which the metal wires 4a ₇ and 4a ₈ are positioned are orthogonal to the second to fourth straight lines.

Further, the metal sphere 5a ₂ is provided at the intersection of the first straight line and the fourth straight line where the metal wire 4a ₃ and the metal wire 4a ₆ are located. The metal sphere 5a ₁ is provided on the opposite side of the metal sphere 5a ₂ with respect to the metal wire 4a ₃ . That is, located metal wire 4a ₃ between the metal balls 5a ₁ and the metal ball 5a _2. The metal sphere 5a ₃ is provided on the opposite side of the metal sphere 5a ₂ with respect to the metal wire 4a ₆ . That is, the metal wire 4a ₆ is located between the metal sphere 5a ₃ and the metal sphere 5a ₂ . Therefore, the metal sphere 5a ₁ , the metal wire 4a ₃ , the metal sphere 5a ₂ , the metal wire 4a ₆ , and the metal sphere 5a ₃ are located on the fourth straight line.

On the other hand, the lower surface 3b is provided with metal wires 4b _{1 to} 4b ₆ embedded in six grooves, respectively, and metal balls 5b ₁ and 5b ₂ embedded in two holes, respectively. When the upper surface 3a is projected in parallel on the lower surface 3b, the metal line 4b ₁ is provided at a position overlapping the metal line 4a ₁ and the metal line 4a ₄ provided on the upper surface 3a, and the metal line 4b ₂ is provided on the upper surface 3a. Are provided at positions overlapping with the metal wire 4a ₂ and the metal wire 4a ₅ respectively. The metal line 4b ₃ and the metal line 4b ₄ are provided so as to overlap the metal line 4a ₃ and the metal line 4a ₆ on the upper surface 3a, respectively. That is, the metal line 4b ₃ and the metal line 4b ₄ are located on the same straight line. The metal lines 4b ₅ and 4b ₆ are provided at positions overlapping the metal lines 4a ₇ and 4a ₈ provided on the upper surface 3a, respectively.

Metal ball 5b ₁ is provided at an end portion close to the metal wire 4b ₁ of the two ends of the metal wire 4b _5, metal balls 5b ₂ is close to the metal wire 4b ₂ of the two ends of the metal wire 4b ₆ Provided at the end. When parallel projection the upper surface 3a to the lower surface 3b, the straight line connecting the metal ball 5b ₁ and the metal ball 5b ₂ is orthogonal to the straight line connecting the metal ball _{5a 1, 5a 2, 5a 3} .

Also, a pair of side surfaces of the rectangular parallelepiped member, for example, a side surface 3c on the far side and a side surface 3d on the near side, are provided with metal wires and metal balls embedded in the groove. The side surface 3c, respectively the metal wire _4c 1 _{~4c 4} embedded in four grooves, and the metal balls _5c 1 _{~5c 3} embedded each of the three holes is provided. Metal wire 4c ₁ and the metal wire 4c ₂ is disposed on the same straight line (fifth straight line). Metal lines 4c ₃ and the metal wire 4c ₄ is disposed on the same straight line (6 straight), the sixth straight line perpendicular to the fifth straight metal wire c ₁ and the metal wire 4c ₂ are arranged. The metal spheres 5c ₁ , 5c ₂ , 5c ₃ are arranged on the fifth straight line. The metal wire 4c ₁ is disposed between the metal sphere 5c ₁ and the metal sphere 5c _2, and the metal wire 4c ₂ is disposed between the metal sphere 5c ₂ and the metal sphere 5c ₃ .

Further, the side surfaces 3d, respectively the metal wire _4d 1 _{~4d 4} embedded in four grooves, each embedded metal balls _5d the two holes 1, 5d ₂ and is provided. Metal wire 4d ₁ and the metal wire 4d ₂ is disposed on the same straight line (7 straight). Metal wire 4d ₃ and the metal wire 4d ₄ is disposed on the same straight line (8 straight), the eighth straight line perpendicular to the seventh straight metal wire d ₁ and the metal wire 4d ₂ is arranged. Metal balls 5d _1, to the metal wire 4d _3, is disposed at the end opposite to the seventh line and the intersection between the eighth straight. The metal sphere 5d ₂ is disposed at the end of the metal line 4d ₄ opposite to the intersection of the seventh straight line and the eighth straight line. When the side surface 3 is projected in parallel on the side surface 3c, the metal lines 4d ₁ , 4d ₂ overlap the metal lines 4c ₁ , 4c ₂ on the side surface 3c, and the metal lines 4d ₃ , 4d ₄ correspond to the metal lines 4c _{3 on} the side surface 3c, 4c Overlaps ₄

(How to align with building standards)
Next, a method for aligning with the building reference using the phantom according to the embodiment configured as described above will be described with reference to FIG. FIG. 3 is a top view of a treatment room in a building where a particle radiation device and an X-ray imaging device of the radiation treatment device are installed.

  In the treatment room, a support base 43 is placed on the floor 32, and a plate 42 on which the phantom 1 is placed is provided on the support base 43. The support base 43 is driven by a drive unit (not shown) so as to be movable in a direction parallel to and perpendicular to the floor 32. The plate 42 and the support base 43 are made of a material that transmits visible light.

Wall surface building standards 64 ₁ and 64 ₂ are affixed to a pair of walls facing each other in the treatment room. Further, wall surface building standards 64 ₃ and 64 ₄ are also affixed to a pair of opposing walls orthogonal to the pair of opposing walls, respectively. Each wall building standard 64 _i (i = 1,..., 4) has, for example, a cross mark. A straight line connecting the centers of the wall building standards 64 ₂ cross mark cross mark wall building standards 64 _1, the center of the cross mark and the center of the wall building standards 64 ₄ cross mark wall building standards 64 ₃ The connecting straight lines are orthogonal to each other.

Vertical plane between the vertical plane optics (theodolites) 61 is provided, the support base 43 and the wall building standards 64 ₁ affixed to the wall between the support 43 and the wall building standards 64 ₃ affixed to walls An optical device (theodolite) 62 is provided. The radiation treatment beam port 51 is provided adjacent to the wall of the wall building standards 64 ₄ is attached.

Theodolite 61, its optical axis of the cross mark wall building standards 64 ₃ as well as located in a plane including the vertical portion of the cross mark in the vertical portion and the wall building standards 64 ₄ cross mark wall building standards 64 ₃ It is inclined with respect to the plane including the horizontal portion of the cross mark in the horizontal portion and the wall building standards 64 _4. This inclination angle is an angle at which the laser light emitted from the theodolite 61 irradiates the phantom 1 placed on the plate 42 obliquely from above.

On the other hand, theodolite 62, its optical axis is the wall building standards 64 ₁ while positioned in a plane including the vertical portion of the vertical portion and the wall building standards 64 ₂ cross mark cross mark wall building standards 64 ₁ cross It is inclined with respect to a plane including a horizontal portion and the wall building standards 64 ₂ of the horizontal portion of the cross mark of the mark. This inclination angle is an angle at which the laser light emitted from the theodolite 62 irradiates the phantom 1 placed on the plate 42 obliquely from above.

Further, a horizontal plane optical device (auto level) 63 is provided between theodolite 61 and theodolite 62. The auto level 63 is, for example, a telescope. The optical axis of the auto level 63 is adjusted so as to be the same height as the horizontal portion of the cross mark of each wall building reference 64 _i (i = 1,..., 4). Further, the optical axis of the auto level 63 is inclined by 45 degrees with respect to the optical axis of the theodolite 61, for example.

Theodolite 62 and the floor surface the building standards 65 ₁ is provided on the portion of the floor 32 between the support 43, support 43 and the wall building standards 64 ₂ on part of the floor 32 between the walls affixed floor building standards 65 ₂ is provided. Further, between the theodolite 61 and support 43 on the portion of the floor 32 the floor building standards 65 ₃ provided in the floor 32 between the support 43 and the wall building standards 64 ₄ wall is attached floor building standards 65 ₄ is provided on the portion. Each floor building standard 65 _i (i = 1,..., 4) has, for example, a cross mark.

The straight line connecting the centers of the wall building standards 64 ₁ and 64 ₂ (the center of the cross mark) and the straight line connecting the centers of the floor building standards 65 ₁ and 65 ₂ (the center of the cross mark) are located in the same plane. The straight line connecting the centers of the wall building standards 64 ₃ and 64 ₄ (the center of the cross mark) and the straight lines connecting the centers of the floor building standards 65 ₃ and 65 ₄ (the center of the cross mark) are in the same plane. Located in.

  In the treatment room configured as described above, the phantom 1 is aligned with the building reference as follows.

First, the phantom 1 is placed on the plate 42. At this time, the phantom 1 shown in FIG. 1 is placed so that the surface 3b is the lower surface and the surface 3a is the upper surface. Further, the side surface 3d of the phantom 1 is placed so as to face the wall surface building reference 64 ₃ , that is, the theodolite 61.

In this state, the radiologist looks into the auto level 63 and looks at the phantom. Then, a metal wire _4d 1, 4d ₂ provided on the side surface 3d of the phantom 1, the metal wire _4c 1, 4c ₂ provided on the side surface 3c, but matches the horizontal portion of the cross mark wall building standards 64 ₂ As described above, the height of the support base 43 is adjusted. This adjustment, alignment about a plane including the horizontal portion of the wall building standards 64 _1, 64 ₂ of the cross mark respectively is completed.

Next, a laser beam is emitted from the theodolite 61, and the metal wires 4a ₇ and 4a ₈ provided on the upper surface 3a of the phantom 1 and the metal wires 4c ₃ and 4c ₄ provided on the side surface 3c are the floor building reference 65. ₄ so as to be located on one of the lines and the same straight line of the cross mark, connecting the centers of the floor building standards 65 ₂ cross mark cross mark of the phantom 1 floor surface building standards 65 ₁ The support base 43 is adjusted so as to move horizontally in parallel with the straight line. Here, the said one line of the cross mark floor building standards 65 _4, means a straight line parallel to the straight line connecting the floor building standards 65 ₃ center and the floor surface the building standards 65 ₄ center . By this adjustment, the positioning for the plane including the vertical portions of the cross marks of the wall surface building standards 64 ₃ and 64 ₄ is completed.

Next, a laser beam is emitted from the theodolite 62, and the metal wires 4 a ₃ , 4 a ₆ provided on the upper surface 3 a of the phantom 1 and the metal wires 4 b ₃ , 4 b ₄ provided on the bottom surface 3 b are the floor building standard 65. so as to be positioned on the same straight line and one line of the _two cross mark, connecting the centers of the cross mark floor building standards 65 ₄ cross marks the phantom 1 floor surface building standards 65 ₃ The support base 43 is adjusted so as to move horizontally in parallel with the straight line. Here, the said one line of the cross mark floor building standards 65 _2, refers to a straight line parallel to the straight line connecting the centers of the floor surface the building standards 65 ₂ floor building standards 65 ₁ . This adjustment, alignment about a plane containing the wall building standards 64 _1, 64 ₂ of the vertical part of the cross mark respectively is completed.

  As described above, the alignment between the phantom 1 and the building reference is completed. After this alignment is complete, theodolites 61 and 62 and auto level 63 are moved. However, the support base 43 does not move and the phantom 1 is placed on the plate 42 and is aligned with the building reference.

(Positioning method with X-ray imaging device)
Next, alignment with the X-ray imaging apparatus will be described with reference to FIG. Figure 4 is a front view of the X-ray imaging apparatus from the wall building standards 64 _1. A pit 33 is provided immediately below the support base 43, and the X-ray tube 12 is stored in the pit 33. The X-ray tube 12 emits X-rays from directly below the support base 43 toward the phantom 1. A flat panel detector 22 that detects X-rays from the X-ray tube 12 is provided directly above the phantom 1.

Also, it pits 34 and 35 are provided respectively at portions of the both sides of the floor 32 of the straight line a and pits 33 which connects the respective centers of the floor surface the building standards ₆₅ 3, 65 _4. X-ray tubes 13 and 14 are stored in these pits 34 and 35, respectively. Each of the X-ray tubes 13 and 14 emits X-rays obliquely from below toward the phantom 1 placed on the plate 42. A flat panel detector 23 for detecting X-rays from the X-ray tube 13 is provided obliquely above the phantom 1 (on the left side in the drawing). A flat panel detector 24 for detecting X-rays from the X-ray tube 14 is provided obliquely above the phantom 1 (on the right side in the drawing).

Further, the wall surface building standards 64 _3, X-ray tube 11 is provided between the phantom 1. The X-ray tube 11 is placed on the support base 31 and emits X-rays toward the side surface 3 d of the phantom 1. A flat panel detector 21 that detects X-rays from the X-ray tube 11 is provided on the opposite side of the phantom 1 from the X-ray tube 11.

  In the treatment room in which the X-ray tube is arranged in this manner, the X-ray imaging apparatus (X-ray tube and flat panel detector) is aligned with the phantom 1 as follows.

First, X-rays are emitted from the X-ray tube 11 toward the phantom 1. The X-rays are emitted from the side surface 3d of the phantom 1 toward the side surface 3c facing the side surface 3d. The emitted X-ray is detected by the flat panel detector 21. Based on the detected X-ray image (hereinafter also referred to as X-ray image), the position and angle of the radiation axis of the X-ray tube 11 are calibrated, and the position of the flat panel detector 21 and the angle of the surface that receives the X-rays. Calibrate The calibration with metal wire _4d 1 provided, 4d ₂ and the metal wire _4c 1 provided on the side surface 3c, and 4c ₂ are positioned on the same straight line on the side surfaces 3d, metal lines provided on the side surface 3d 4d ₃ , 4d ₄ and the metal wires 4c ₃ , 4c ₄ provided on the side surface 3c are located on the same straight line, and the metal balls 5d ₁ , the metal wire 4d ₃ , the metal wire 4d ₄ , provided on the side surface 3d, And a straight line connecting the metal balls 5d ₂ and a straight line connecting the metal balls 5c ₁ , the metal wires 4c ₁ , the metal balls 5c ₂ , the metal wires 4c ₂ , and the metal balls 5c ₃ provided on the side surface 3c are orthogonal to each other. Do. Thereby, the X-ray tube 11 and the flat panel detector 21 complete the alignment with the phantom 1, that is, the alignment with the building reference.

Next, X-rays are emitted from the X-ray tube 12 toward the phantom 1. The X-rays are emitted from the lower surface 3b of the phantom 1 toward the upper surface 3a facing the lower surface 3b. This emitted X-ray is detected by the flat panel detector 22. Based on the detected X-ray image, the position and angle of the radiation axis of the X-ray tube 12 are calibrated, and the position of the flat panel detector 22 and the angle of the surface receiving the X-ray are calibrated. In this calibration, the metal wires 4b ₃ and 4b ₄ provided on the lower surface 3b and the metal wires 4a ₃ and 4a ₄ provided on the upper surface 3a are located on the same straight line, and the metal wire 4b provided on the lower surface 3b. ₅ , 4b ₆ and metal wires 4a ₇ , 4a ₈ provided on the upper surface 3a are located on the same straight line, and metal balls 5b ₁ , metal wires 4b ₅ , metal wires 4b ₆ provided on the lower surface 3b, and The straight line connecting the metal balls 5b ₂ and the straight lines connecting the metal balls 5a ₁ , the metal wires 4a ₃ , the metal balls 5a ₂ , the metal wires 4a ₆ , and the metal balls 5a ₃ provided on the upper surface 3a are orthogonal to each other. . Thereby, the X-ray tube 12 and the flat panel detector 22 complete the alignment with the phantom 1, that is, the alignment with the building reference.

Next, X-rays are emitted from the X-ray tube 13 toward the phantom 1. The X-rays are emitted from the lower right side of the phantom 1 toward the upper left side in FIG. This emitted X-ray is detected by the flat panel detector 23. Based on the detected X-ray image, the position and angle of the radiation axis of the X-ray tube 13 are calibrated, and the position of the flat panel detector 23 and the angle of the surface receiving the X-ray are calibrated. This calibration is performed so that the metal wire 4b ₂ provided on the lower surface 3b and the metal wires 4a ₁ and 4a ₄ provided on the upper surface 3a are located on the same straight line. Thereby, the X-ray tube 13 and the flat panel detector 23 complete the alignment with the phantom 1, that is, the alignment with the building reference.

Next, X-rays are emitted from the X-ray tube 14 toward the phantom 1. This X-ray is radiated from the lower left diagonal of the phantom 1 toward the upper right diagonal in FIG. This emitted X-ray is detected by the flat panel detector 24. Based on the detected X-ray image, the position and angle of the radiation axis of the X-ray tube 14 are calibrated, and the position of the flat panel detector 24 and the angle of the surface receiving the X-ray are calibrated. This calibration is performed so that the metal wire 4b ₁ provided on the lower surface 3b and the metal wires 4a ₂ and 4a ₅ provided on the upper surface 3a are located on the same straight line. Thereby, the alignment of the X-ray tube 14 and the flat panel detector 24 with the phantom 1, that is, the alignment with the building reference is completed. Here, the metal balls 5a ₁ , 5a ₂ , 5a ₃ , 5b ₁ , 5b ₂ , 5c ₁ , 5c ₂ , 5c ₃ , 5d ₁ , 5d ₂ of the phantom 1 when the alignment with the building reference is completed. The coordinates of the captured image are stored in each flat panel detector. The coordinates of these images are used to correct a displacement of the treatment table described later.

  As described above, the alignment between the X-ray imaging apparatus including the X-ray tubes 11, 12, 13, and 14 and the building reference is completed. After this alignment is completed, the position of the X-ray tube 11 and the positions of the flat panel detectors 21 and 22 are stored. Thereafter, the X-ray tube 11 and the flat panel detector 22 are moved upward, and the flat panel detector 21 is moved horizontally to the floor surface. However, the support base 43 does not move and the phantom 1 is placed on the plate 42 and is aligned with the building reference.

(Positioning method with therapeutic beam radiation device (particle radiation device))
Next, alignment with the treatment beam radiation apparatus will be described with reference to FIG. Figure 5 is a front view of the treatment beam emitting device from the wall surface building standards 64 _1. As described in FIG. 3, radiation treatment beam ports (hereinafter, the treatment also referred to as a beam port) adjacent to the wall of the wall building standards 64 ₄ is attached 51 is provided. As shown in FIG. 5, a radiation treatment beam port (hereinafter also referred to as a treatment beam port) 52 is provided immediately above the phantom 1. A radiation treatment beam monitor (hereinafter also referred to as a treatment beam monitor) 53 that receives a radiation treatment beam (hereinafter also referred to as a treatment beam) is provided on the opposite side of the phantom 1 from the treatment beam port 51. Further, a radiation treatment beam monitor (hereinafter also referred to as a treatment beam monitor) 54 that receives a radiation treatment beam on the opposite side of the treatment beam port 52 with respect to the phantom 1 is provided.

  In the treatment room where such a particle radiation apparatus is arranged, the alignment of the particle radiation apparatus (the treatment beam port and the treatment beam monitor) with respect to the phantom 1 is performed as follows.

First, a treatment beam is irradiated from the treatment beam port 51 toward the side surface 3d of the phantom 1. This treatment beam enters the side surface 3d, passes through the phantom 1, enters the treatment beam monitor 53 from the side surface 3c of the phantom 1, is detected, and an image of the treatment beam is displayed. Based on the image of the treatment beam displayed by the treatment beam monitor 53, the position and angle of the radiation axis of the treatment beam port 51 are calibrated, and the position of the treatment beam monitor 53 and the angle of the surface receiving the treatment beam are calibrated. These calibration, along with the metal wire _4c 1 provided, 4c ₂ and the metal wire _4d 1 provided on the side surface 3d, and 4d ₂ are positioned on the same straight line on the side surface 3c, metal lines provided on the side surface 3c 4c ₃ , 4c ₄ and the metal wires 4d ₃ , 4d ₄ provided on the side surface 3d are located on the same straight line, and the metal balls 5d ₁ , the metal wire 4d ₃ , the metal wire 4d ₄ , provided on the side surface 3d, And a straight line connecting the metal balls 5d ₂ and a straight line connecting the metal balls 5c ₁ , the metal wires 4c ₁ , the metal balls 5c ₂ , the metal wires 4c ₂ , and the metal balls 5c ₃ provided on the side surface 3c are orthogonal to each other. Do. Thereby, the alignment of the treatment beam port 51 and the treatment beam monitor 53 with the phantom 1, that is, the alignment with the building reference is completed.

Subsequently, the treatment beam is irradiated from the treatment beam port 52 toward the upper surface 3 a of the phantom 1. After this treatment beam is incident on the upper surface 3a, it passes through the phantom 1, enters the treatment beam monitor 54 from the lower surface 3b of the phantom 1, is detected, and an image of the treatment beam is displayed. Based on the image of the treatment beam displayed by the treatment beam monitor 54, the position and angle of the radiation axis of the treatment beam port 52 are calibrated and the position of the treatment beam monitor 54 and the angle of the surface receiving the treatment beam are calibrated. In this calibration, the metal wires 4b ₃ and 4b ₄ provided on the lower surface 3b and the metal wires 4a ₃ and 4a ₄ provided on the upper surface 3a are located on the same straight line, and the metal wire 4b provided on the lower surface 3b. ₅ , 4b ₆ and metal wires 4a ₇ , 4a ₈ provided on the upper surface 3a are located on the same straight line, and metal balls 5b ₁ , metal wires 4b ₅ , metal wires 4b ₆ provided on the lower surface 3b, and The straight line connecting the metal balls 5b ₂ and the straight lines connecting the metal balls 5a ₁ , the metal wires 4a ₃ , the metal balls 5a ₂ , the metal wires 4a ₆ , and the metal balls 5a ₃ provided on the upper surface 3a are orthogonal to each other. . Thereby, the alignment of the treatment beam port 52 and the treatment beam monitor 54 with the phantom 1, that is, the alignment with the building reference is completed.

  As described above, the alignment of the treatment beam radiation device including the treatment beam ports 51 and 52 and the building reference is completed. When this alignment is completed, the plate 42 is removed from the phantom 1, and the support base 43 and the plate 42 are also removed. Thereafter, as shown in FIG. 6, the treatment table 45 and the top board 44 placed on the treatment table 45 are carried into the treatment room. The top plate 44 and the treatment table 45 are made of a material that transmits X-rays.

(Method for positioning the treatment table)
As shown in FIG. 6, using the phantom 1 placed on the top 44, the treatment table 45 is aligned as follows.

  First, the phantom 1 is placed on the top plate 44, the flat panel detectors 21, 22, 23, 24 of the X-ray imaging device are returned to the stored positions, and the support base 31 is moved to move the support base 31 onto the support base 31. Is returned to the stored position. At this time, the phantom 1 is placed on the top plate 44 as in the case of alignment with the X-ray imaging apparatus. That is, the phantom 1 is disposed such that the lower surface 3 b is in contact with the top plate 44 and the side surface 3 d is opposed to the X-ray tube 11.

In this state, X-rays are irradiated from the X-ray tube 11 toward the side surface 3d of the phantom 1 on the top plate 44. The irradiated X-rays are detected by the flat panel detector 21 after passing through the phantom 1. Based on the X-ray image detected by the flat panel detector 21, the coordinates of the metal balls 5 c ₁ , 5 c ₂ , 5 c ₃ , 5 d ₁ , 5 d ₂ are obtained.

Subsequently, X-rays are irradiated from the X-ray tube 12 toward the lower surface 3 b of the phantom 1. The irradiated X-rays are detected by the flat panel detector 22 after passing through the phantom 1. Based on the X-ray image detected by the flat panel detector 21, the coordinates of the metal balls 5 c ₁ , 5 c ₂ , 5 c ₃ , 5 d ₁ , 5 d ₂ are obtained.

Thereafter, X-rays are irradiated from the X-ray tube 12 toward the lower surface 3 b of the phantom 1. The irradiated X-rays are detected by the flat panel detector 22 after passing through the phantom 1. Based on the X-ray image detected by the flat panel detector 22, the coordinates of the metal balls 5c ₁ , 5c ₂ , 5c ₃ , 5d ₁ , 5d ₂ are obtained.

Thereafter, X-rays are irradiated from the X-ray tube 13 toward the phantom 1 from the lower right of FIG. The irradiated X-rays are detected by the flat panel detector 23 after passing through the phantom 1. Based on the X-ray image detected by the flat panel detector 23, the coordinates of the metal balls 5 a ₁ , 5 a ₂ , 5 a ₃ , 5 b ₁ , 5 b ₂ , 5 c ₁ , 5 c ₂ , 5 c ₃ , 5 d ₁ , 5 d ₂ are obtained. Ask.

Furthermore, X-rays are irradiated from the X-ray tube 14 toward the phantom 1 from the lower left of FIG. The irradiated X-ray is detected by the flat panel detector 24 after passing through the phantom 1. Based on the X-ray image detected by the flat panel detector 24, the coordinates of the metal balls 5 a ₁ , 5 a ₂ , 5 a ₃ , 5 b ₁ , 5 b ₂ , 5 c ₁ , 5 c ₂ , 5 c ₃ , 5 d ₁ , 5 d ₂ are obtained. Ask.

In this way, the metal spheres 5a ₁ , 5a ₂ , 5a ₃ , 5b ₁ , 5b ₂ , 5c ₁ , 5c ₂ , 5c ₃ obtained from the X-ray images detected by the flat panel detectors 21, 22, 23, 24. 5d ₁ , 5d ₂ , and metal spheres 5a ₁ , 5a ₂ obtained from X-ray images detected by the flat panel detectors 21, 22, 23, 24 obtained by alignment with the X-ray imaging device The shift amount of the treatment table 45 is obtained from the coordinates of 5a ₃ , 5b ₁ , 5b ₂ , 5c ₁ , 5c ₂ , 5c ₃ , 5d ₁ , 5d ₂ .

(Calculation of deviation)
The shift amount of the treatment table 45 is obtained as follows.

ここで、Ｒは回転ずれを表す３×３行列、Ｔは並進ずれを表す３×１行列、Ｏは１×３の零行列である。 An example of the concept of calculating the deviation amount from the obtained X-ray image of the phantom 1 will be described. In this example, the position of the X-ray imaging system (X-ray tube, flat panel detector) is calibrated, and the reference position (isocenter) of the treatment table (bed) is shifted by translation and rotation. With respect to the correct reference point coordinates (x, y, z) of one metal sphere of the phantom 1, the coordinates (x ′, y ′, z ′) when translation and rotational deviation occur are as follows: It can be expressed by a formula.

Here, R is a 3 × 3 matrix representing a rotational deviation, T is a 3 × 1 matrix representing a translational deviation, and O is a 1 × 3 zero matrix.

ここで、基準点座標（ｘ、ｙ、ｚ）と、ずれを生じた座標（ｘ‘、ｙ’、ｚ‘）は、３次元空間での座標であるが、これがＸ線撮像系ではフラットパネルディテクタ上に２次元座標として観測される。これらの２次元座標をそれぞれ（Ｘ，Ｙ），（Ｘ’，Ｙ’）とする。Ｘ線管を点光源とすれば、射影画像を考えればよい。Ｌを点光源からフラットパネルディテクタまでの距離とすると、（Ｘ’，Ｙ’）は次の（３）式で表される。

ここで、求めるべき未知数は、ずれに関する（φ，θ，ψ，ｐ、ｑ、ｒ）の６つである。したがって、複数（３以上）の金属球の基準点座標（ｘ、ｙ、ｚ）に対して、観測座標（Ｘ’，Ｙ’）が得られれば、ずれに関する未知数を算出することができる。ただし、現実的には解析的に算出することが困難であり、また得られた観測座標（Ｘ’、Ｙ’）も画像処理で求めていることもあるので、最適化アプローチを使用する。例えば、求められた（φ‘、θ’、ψ‘、ｐ’、ｑ‘、ｒ’）に対して算出される（ｘ‘’、ｙ‘’、ｚ‘’）に対応する撮像点（Ｘ’’，Ｙ’’）に関して、下記の（４）式、すなわち偏差の二乗和が最小となるようにずれ量を求める。

ここで、ｉは観測に用いる金属球の番号に相当する。 The relationship between the reference point coordinates (x, y, z) and the coordinates (x ′, y ′, z ′) where translation and rotational deviation occur is as shown in FIGS. 7A and 7B, for example. Considering the rotational deviation R composed of the rolling angle φ, the pitching angle θ, and the yawing angle ψ, and the translational deviation T composed of (p, q, r), the above equation (1) is specifically expressed by the following equation (2): Can be written as

Here, the reference point coordinates (x, y, z) and the offset coordinates (x ′, y ′, z ′) are coordinates in a three-dimensional space, but this is a flat panel in the X-ray imaging system. Observed as two-dimensional coordinates on the detector. These two-dimensional coordinates are (X, Y) and (X ′, Y ′), respectively. If an X-ray tube is used as a point light source, a projected image may be considered. When L is the distance from the point light source to the flat panel detector, (X ′, Y ′) is expressed by the following equation (3).

Here, there are six unknowns to be obtained (φ, θ, ψ, p, q, r) related to the deviation. Therefore, if the observation coordinates (X ′, Y ′) are obtained with respect to the reference point coordinates (x, y, z) of a plurality (three or more) of metal spheres, an unknown number relating to the deviation can be calculated. However, in reality, it is difficult to calculate analytically, and the obtained observation coordinates (X ′, Y ′) may be obtained by image processing, so an optimization approach is used. For example, the imaging point (X ”corresponding to (x ″, y ″, z ″) calculated for the obtained (φ ′, θ ′, ψ ′, p ′, q ′, r ′). '', Y ''), the amount of deviation is obtained so that the following equation (4), that is, the sum of squares of the deviation is minimized.

Here, i corresponds to the number of the metal sphere used for observation.

  Based on the amount of deviation, calibration of the treatment table 45 with respect to the three translational axes and the three rotation axes is performed. Thereby, it becomes possible to calibrate the displacement of the movable axis of the radiotherapy apparatus, and alignment between the radiotherapy apparatus and the building reference can be performed.

  As described above, using the phantom 1, it is possible to perform alignment with the building reference, alignment with the X-ray imaging apparatus, and alignment with the radiation therapy apparatus. Thereby, while being able to judge correctly the position shift of the movable axis | shaft of a radiotherapy apparatus, it can apply to position alignment with a building reference | standard, and position alignment with a some apparatus.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

1 Phantom (Phantom) for calibration of radiation therapy equipment
3a the upper surface 3b underside 3c, 3d side _{4a 1, 4a 2, 4a 3} , 4a 4, 4a 5, 4a 6, 4a 7, 4a 8 metal wire _{4b 1, 4b 2, 4b 3} , 4b 4, 4b 5, 4b 6 metal wire _{4c 1, 4c 2, 4c 3} , 4c 4 metal wire _{4d 1, 4d 2, 4d 3} , 4d 4 metal wire _{5a 1,} 5a 2, 5a ₃ metal balls 5b _1, 5b ₂ metal balls 5c _1, 5c ₂ 5c ₃ metal spheres 5d ₁ , 5d ₂ metal spheres

Claims (6)

A rectangular parallelepiped structural member formed of a material capable of transmitting visible light, the first and second surfaces facing each other, and the third and fourth surfaces facing each other;
First and second metal wires provided on the first surface and arranged in a cross shape with each other;
A first metal sphere provided at one end of the first metal wire and a second metal sphere provided at the other end of the first metal wire;
Third and fourth metal lines provided on the second surface and arranged in a cross shape with each other, the third metal line being the second metal when the second surface is projected in parallel on the first surface Third and fourth metal lines, at least partly overlapping with the line and the fourth metal line overlapping at least partly with the first metal line;
A third metal sphere provided at one end of the third metal line and a fourth metal sphere provided at the other end of the third metal line;
Fifth and sixth metal wires provided on the third surface and arranged in a cross shape with each other;
A fifth metal sphere provided at one end of the fifth metal line and a sixth metal sphere provided at the other end of the fifth metal line;
Seventh and eighth metal lines provided on the fourth surface and arranged in a cross shape with each other, and the seventh metal line is the sixth metal when the fourth surface is projected in parallel on the third surface. Seventh and eighth metal lines, at least partly overlapping the line and the eighth metal line overlapping at least partly with the fifth metal line;
A seventh metal sphere provided at one end of the seventh metal wire and an eighth metal sphere provided at the other end of the seventh metal wire;
A phantom for calibration of radiation therapy equipment.   The radiotherapy apparatus calibration phantom according to claim 1, wherein the first to eighth metal wires are separated on the way.   A ninth metal sphere provided at the intersection of the first metal line and the second metal line; and a tenth metal sphere provided at the intersection of the fifth metal line and the sixth metal line. 3. A radiation therapy apparatus calibration phantom according to claim 1 or 2. Ninth and tenth metal lines provided on the first surface and disposed on both sides of the first metal line;
Eleventh and twelfth metal wires provided on the second surface and disposed on both sides of the four metal wires;
The radiation therapy apparatus calibration phantom according to any one of claims 1 to 3, further comprising: The structural member includes a first plate member having the first surface, a second plate member having the second surface, a third plate member having the third surface, and a fourth plate having the fourth surface. A member, a fifth plate member having the five surfaces, and a sixth plate member having the sixth surface,
Each of the metal wirings is embedded in a groove provided in a corresponding plate member,
5. The radiotherapy apparatus calibration phantom according to claim 1, wherein each of the metal spheres is disposed on a back surface side of a corresponding plate member. Placing the radiation therapy apparatus calibration phantom according to claim 1 on a support in a treatment room;
Vertically moving and horizontally moving the support table so that the metal line of the radiation therapy apparatus calibration phantom matches the building standard provided on the wall and floor of the treatment room by the horizontal optical device and the vertical optical device; ,
The radiation therapy apparatus calibration phantom placed on the support is irradiated with X-rays from each X-ray tube of the X-ray imaging apparatus, and detected by the corresponding X-ray detector through the radiation therapy apparatus calibration phantom. Based on the image of the metal line detected by each X-ray detector, the irradiation axis of each X-ray tube so that the cross-shaped metal lines provided on the opposing surfaces of the radiotherapy apparatus calibration phantom overlap each other And the position of the X-ray detector and the angle of the surface of the X-ray detector that receives the X-ray, and the first position coordinates of the position of each metal sphere after the adjustment, Obtaining and storing the image of the metal sphere detected by the X-ray detector;
The radiation therapy apparatus calibration phantom placed on the support is irradiated with a radiation therapy beam from each treatment beam port of the therapy beam radiation apparatus, and detected by the corresponding therapy beam monitor through the radiation therapy apparatus calibration phantom. Based on the image of the metal line detected by each treatment beam monitor, the irradiation axis of each treatment beam port is set so that the cross-shaped metal lines provided on the opposing surfaces of the radiotherapy apparatus calibration phantom overlap each other. Adjusting the position and angle, the position of the treatment beam monitor and the angle of the treatment beam monitor surface receiving the treatment beam;
After removing the support table, the radiation therapy apparatus calibration phantom is placed on the treatment table, X-rays are irradiated from the radiation tube of the X-ray imaging apparatus to the radiation therapy apparatus calibration phantom, and the radiation therapy is performed. Obtaining a second position coordinate of each metal sphere of the apparatus calibration phantom from the image of the metal sphere detected by the X-ray detector;
Calibrating the position of the treatment table based on the first position coordinates and the second position coordinates of each metal sphere;
A method for aligning a radiotherapy apparatus comprising:

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