JP2013046709A - Displacement measurement method of isocenter in radiotherapy apparatus, adjustment method of displacement of the same, and phantom for displacement measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement method for measuring displacement (deviation) of an isocenter of treatment X-rays, a virtual isocenter by a laser beam for position determination, and a center position irradiated with diagnosis X-rays from a diagnosis X-ray photography device in a radiotherapy apparatus, an adjustment method for adjusting the displacement, and to provide a phantom for displacement measurement used in the measurement method and the adjustment method.SOLUTION: The measurement method executes, in an arbitrary order, a step of measuring the displacement of the position of an actual isocenter 71 by the treatment X-rays and the position of an X-ray absorber disposed at a virtual isocenter from irradiation image information obtained by irradiating the X-ray absorber embedded inside the phantom 10 with the treatment X-rays for the displacement measurement from a gantry 41 of the radiotherapy apparatus 4, and a step of measuring the displacement of the center position of the diagnosis X-rays and the position of the X-ray absorber disposed at the virtual isocenter from irradiation image information obtained by irradiating the X-ray absorber with the diagnosis X-rays from the diagnosis X-ray photography device 44.

Description

  The present invention relates to a method for measuring displacement of an isocenter in a radiotherapy apparatus and a method for adjusting the displacement. According to the present invention, it is possible to measure the displacement (displacement) between the isocenter (the actual isocenter) of therapeutic X-rays and the virtual isocenter of the position determining irradiation beam (for example, laser light) in the radiotherapy apparatus. In addition, the displacement (displacement) can be adjusted (or corrected) using the measured value. The present invention also relates to a displacement measuring phantom that can be used in the displacement measuring method.

  In the treatment of cancer, treatment methods such as surgery, chemotherapy, radiation therapy, or immunotherapy are mainly used. Among these treatment methods, radiotherapy is performed by irradiating cancer cells with electromagnetic waves (for example, X-rays or γ-rays) or particle beams (for example, electron beams, proton beams, or neutron beams). Is a way to kill. This radiation therapy is aimed at delivering enough radiation into the body to kill cancer cells, while avoiding damage to normal tissue.

In radiotherapy using X-rays as electromagnetic waves, a radiotherapy apparatus has been conventionally used, and imaging of a treatment site has been performed using ultrahigh-pressure X-rays for confirmation of the radiotherapy site. Since this ultra-high pressure X-ray is an X-ray having the same high energy as the therapeutic X-ray, sufficient contrast for confirming the treatment site cannot be obtained, and detailed verification has been conducted. There wasn't. Recently, by attaching a diagnostic X-ray imaging apparatus to a radiotherapy apparatus, it has become possible to obtain fine information using low-energy X-rays, and to perform more accurate treatment. (For example, Non-Patent Document 1). A typical example of such a radiation therapy apparatus is shown in FIG.
The radiotherapy apparatus 4 shown in FIG. 1 includes a gantry 41, a gantry rotating means 42, a diagnostic X-ray imaging apparatus 44, and a treatment table 46.

  The gantry 41 generates X-rays (hereinafter referred to as therapeutic X-rays) used for killing cancer cells (cancer tissues) inside the gantry 41 so that the patient lying on the treatment table 46 This is an apparatus for irradiating therapeutic X-rays toward cancer cells (cancer tissue). The therapeutic X-rays are irradiated in the direction of the treatment table 46 from the therapeutic X-ray irradiation unit 41 a provided in the gantry 41.

  The gantry rotating means 42 is a means capable of rotating the gantry 41 360 ° integrally with the diagnostic X-ray imaging apparatus 44 so that the isocenter which is the center position of therapeutic X-ray irradiation is the center of rotation. is there. The isocenter means a point where the bundles of therapeutic X-rays irradiated from the gantry 41 are concentrated, and radiotherapy is performed by matching the isocenter with the target treatment site (cancer tissue) of the patient. To do. By enabling 360 ° rotation by the gantry rotating means 42, it is possible to irradiate therapeutic X-rays from any direction toward the isocenter.

  The diagnostic X-ray imaging apparatus 44 is an apparatus for accurately and precisely measuring the position of cancer cells (cancer tissue) existing in the body of a patient lying on a treatment table 46, and is an X-ray for diagnosis. An irradiation unit 44a and a diagnostic X-ray detection unit 44b are included. The diagnostic X-ray is emitted from the diagnostic X-ray irradiation unit 44a, and the diagnostic X-ray detection unit 44b can acquire a diagnostic X-ray image. That is, although it is difficult to accurately grasp the position of cancer cells (cancer tissue) present in the patient's body from the outside, the diagnostic table is irradiated with diagnostic X-rays from the diagnostic X-ray irradiation unit 44a. The position of cancer cells (cancer tissue) in the patient body is determined based on the information on the surrounding organs by passing through the patient's body above 46 and acquiring an image with the diagnostic X-ray detection unit 44b. An image (or image signal) can be obtained. With the diagnostic X-ray imaging apparatus 44, the position of cancer cells (cancer tissue) in the patient's body is accurately grasped regarding the patient immediately before the radiation treatment, the patient undergoing the radiation treatment, or the patient after the radiation treatment. Therefore, it is possible to more accurately irradiate cancer cells with therapeutic X-rays. The irradiation direction of diagnostic X-rays by the diagnostic X-ray imaging apparatus 44 intersects (especially orthogonal) with the irradiation direction of therapeutic X-rays by the gantry 41 and is arranged so that the optical axes of the two do not coincide with each other. It is preferable. The diagnostic X-ray imaging apparatus 44 can also be rotated 360 ° integrally with the gantry 41 around the isocenter by the gantry rotating means 42. With this 360 ° rotation, X-ray imaging can be performed from any direction.

  The treatment table 46 is a bed for laying a patient receiving radiation therapy and performing radiation therapy. The treatment table 46 includes position adjustment means (not shown) that can adjust the relative position to the gantry 41 and the like, and the treatment table 46 can be moved in various directions by the position adjustment means. By adjusting the movement mechanism of the treatment table 46 and the 360 ° rotation mechanism of the gantry 41 together, avoiding normal tissue and accurately treating X-rays for cancer cells (cancer tissue). Irradiation is possible.

  Although not shown in FIG. 1, the radiation treatment room in which the radiation treatment apparatus 4 is installed is irradiated with position determining laser light from the wall surface (that is, the ceiling or the side wall surface) in the radiation treatment room. ing. This position determining laser beam is used to match the target treatment site of the patient with the isocenter.

Radiotherapy using a radiotherapy apparatus is usually performed by the following steps (1) to (6).
(1) Treatment target diseased part determination process:
The position of the cancer cell (cancer tissue) present in the patient's body is confirmed by a treatment planning CT or the like, and the treatment target diseased part is determined.
(2) Marking process:
In order to indicate the location of the treatment target affected part, an operation of marking (hereinafter referred to as skin mark) on the skin surface of the patient is performed.
(3) Position determination process:
The patient is moved to the radiation therapy room, and work for matching the treatment target diseased part with the isocenter is performed.
(4) X-ray imaging process:
Immediately before irradiation with therapeutic X-rays, X-ray imaging is performed on the patient by a diagnostic X-ray imaging apparatus.
(5) Position fine adjustment process:
The patient is positioned again by comparing the image information obtained by X-ray imaging in the radiation therapy room with the image information obtained by the CT for treatment planning.
(6) Therapeutic X-ray irradiation process:
The patient is irradiated with therapeutic X-rays.

A specific operation in the case where the radiotherapy of the steps (1) to (6) is performed using the radiotherapy apparatus 4 shown in FIG. 1 will be described with reference to FIGS.
In the treatment target diseased part determination step (1), the position of cancer cells (cancer tissue) existing in the body of the patient 3 (see FIGS. 2 and 3) is confirmed by the treatment planning CT or the like, and the treatment target is determined. The affected area 33 is determined.
Next, in the marking step (2), as shown in FIG. 2, in order to indicate the location of the treatment target affected part 33 in the body of the patient 3, two places (point A and point B) on the skin surface of the patient 3 are provided. The skin mark 31 is attached. FIG. 2 shows a state in which the patient 3 is placed on the treatment table 46 in the radiation treatment room after the marking process. The patient 3 is fixed to the treatment table 46 using a patient head fixing pillow 38 and other fixing tools (not shown).

  Subsequently, in the position determination step (3), as shown in FIG. 3, the position determination laser beam 35 is irradiated to the patient 3 from the wall surfaces (ceiling and side surfaces) in the radiation treatment room, and the position determination laser beams 35a and 35b are irradiated. , 35c is moved so that the skin mark 31 and the treatment mark 46 coincide with each other, and the treatment table 46 is fixed at a point completely coincident with the skin mark 31. Here, the position determining laser beams 35a, 35b, and 35c are adjusted so as to intersect at one point, and the intersection (virtual isocenter) is used for treatment irradiated from the gantry 41 of the radiation therapy apparatus 4 It is adjusted so as to completely coincide with the X-ray isocenter (actual isocenter). Therefore, by fixing the treatment table 46 at a point where the position determination laser beams 35a, 35b, and 35c completely coincide with the skin mark 31, the treatment target affected part 33 and the isocenter (actual isocenter) are matched. Can do.

  Specifically, as shown in FIG. 3, the position determination laser beam 35 includes an X-axis direction position determination laser beam 35a, a Y-axis direction position determination laser beam 35b, and a Z-axis direction position determination laser beam. 35c. The X-axis direction position determination laser beam 35a is irradiated in a single plane from the laser beam irradiation means (not shown) provided on the ceiling in the radiation treatment room toward the floor surface, and the patient 3 A linear image 36a is drawn on the body surface of the patient 3 at the contact point (body surface) with the center of the body extending from the vicinity of the throat toward the lower body. The Y-axis direction position determining laser beam 35b is emitted from a laser beam irradiation means (not shown) provided on the side wall surface in the radiation treatment room in a direction parallel to the ceiling and the floor surface, and the X-axis direction position determining laser beam 35a. A linear image 36b extending in the vertical direction on the side surface of the body is drawn at a contact point (body surface) with the patient 3 at a point perpendicular to the plane. The Z-axis direction position determining laser beam 35c is used for determining the X-axis direction position from the laser beam irradiation means (not shown) provided on the ceiling in the radiation therapy room or the radiation therapy apparatus 4 toward the floor surface. A linear image that is irradiated in one plane perpendicular to the laser beam 35a and the laser beam 35b for position determination in the Y-axis direction and extends in a direction transverse to the body at the contact point (body surface) with the patient 3 Draw 36c.

  The intersection C between the linear image 36a by the X-axis direction position determining laser beam 35a and the linear image 36c by the Z-axis direction position determining laser beam 35c is made to coincide with the intersection A of the skin mark 31, and at the same time, the Y-axis When the intersection point D between the linear image 36b by the direction position determining laser beam 35b and the linear image 36c by the Z-axis direction position determining laser beam 35c coincides with the intersection point B of the skin mark 31, the treatment target affected area 33 is isolated. It will be located at the center 37.

  The X-ray imaging process (4) is performed in a state where the treatment target affected area 33 and the virtual isocenter are matched. That is, immediately before irradiation with therapeutic X-rays, X-ray imaging is performed on the patient 3 by the diagnostic X-ray imaging apparatus 44, and the actual position of the treatment target affected area 33 in the body of the patient 3 and the skin mark 31. The displacement (displacement) of the position of the treatment target affected part 33 determined from the above is measured. By performing X-ray imaging at a plurality of angles, the three-dimensional position of the treatment target affected part 33 with higher accuracy can be confirmed. The purpose of measuring this displacement (displacement) is that the marking process (2) and the position determination process (3) are performed at different times (not only at different times but also at different days). This is because the treatment target affected area 33 may be shifted because the internal state is not completely the same due to changes and treatment effects. In radiotherapy, even if there is a very slight deviation, normal tissue is damaged, and it is desired to avoid it. The radiotherapy apparatus that does not include the diagnostic X-ray imaging apparatus uses information captured using the therapeutic X-ray for position confirmation. However, the contrast of the image cannot be obtained and the accuracy is improved. Was missing.

  The position fine adjustment step (5) is performed when displacement (deviation) is detected in the X-ray imaging step (4), and the actual position of the treatment target affected area 33 and the isocenter 37 are completely matched. . Thus, the therapeutic X-ray irradiation step (6) is performed in a state where the position of the treatment target affected area 33 and the isocenter 37 are completely matched.

  In a radiotherapy apparatus that does not include a diagnostic X-ray imaging apparatus, the treatment target affected area and the isocenter are matched only by the skin mark 31 and the position determining laser beam 35, and thus the difference in the degree of fullness of the internal organs of the patient In some cases, the X-rays for treatment could not be accurately irradiated to cancer cells due to the visceral movement accompanying breathing. On the other hand, in the radiotherapy apparatus provided with the diagnostic X-ray imaging apparatus as in the above-described radiotherapy, X-ray imaging is performed before performing radiotherapy on the patient in the radiotherapy room, and the image Radiotherapy performed while confirming the position of cancer cells by using is called image-guided radiation therapy (IGRT). This IGRT method can further improve the accuracy of therapeutic X-ray irradiation.

Kyoto University Hospital Radiology home page “Introduction of treatment facilities” http://radiotherapy.kuhp.kyoto-u.ac.jp/index.php?p=13

According to the IGRT method, therapeutic X-ray irradiation can be performed with high accuracy.
As preconditions for carrying out this IGRT method with high accuracy, an actual isocenter of therapeutic X-rays, a virtual isocenter by a positioning laser beam, and diagnostic X-rays irradiated from a diagnostic X-ray imaging apparatus The center of the line must match. Conventionally, when the radiotherapy apparatus is first installed in the radiotherapy room, the installation work has been carried out in a state where the above three points are accurately matched, but the above three points have been accurately matched. Even if the installation is performed in a state, it is inevitable that the above three points are displaced due to the influence of vibrations such as driving operations and earthquakes repeatedly performed thereafter.
However, conventionally, in a radiotherapy apparatus that implements the IGRT method, an actual isocenter of therapeutic X-rays, a virtual isocenter by a positioning laser beam, and a diagnostic X-ray irradiated from a diagnostic X-ray imaging apparatus There has been no known method for simply carrying out an inspection as to whether or not the center position of a line matches. In addition, when position confirmation is performed based on information captured using therapeutic X-rays, which are high-energy X-rays, image contrast cannot be obtained and accuracy is lacking.
Therefore, an object of the present invention is to measure the actual isocenter of the therapeutic X-ray and the virtual isocenter and displacement (displacement) due to the position determining laser beam in the radiotherapy apparatus including the diagnostic X-ray imaging apparatus. A further object is to provide means for measuring the displacement (displacement) between the actual isocenter of the therapeutic X-ray and the center position of the diagnostic X-ray irradiated from the diagnostic X-ray imaging apparatus.

  Another object of the present invention is to actually move the virtual isocenter and the therapeutic X-ray by moving the virtual isocenter determined by the position determining laser beam using the displacement measurement value. It is an object of the present invention to provide an adjusting means for matching the position of the isocenter and / or the center position of diagnostic X-rays emitted from the diagnostic X-ray imaging apparatus.

  Furthermore, another object of the present invention is to provide a displacement measuring phantom.

The problem is solved by the present invention.
X embedded in a displacement measurement phantom placed on a treatment table in a radiotherapy room with respect to a virtual isocenter determined by a position determining laser beam irradiated from the wall surface in the radiotherapy room The position determining laser beam is characterized in that the displacement measuring phantom is fixed at a position where the linear absorbers coincide with each other, and then the following steps (1) and (2) are performed in an arbitrary order. The displacement of the virtual isocenter position from the actual isocenter position by the therapeutic X-ray irradiated from the gantry of the radiotherapy apparatus and the diagnosis irradiated from the diagnostic X-ray imaging apparatus of the radiotherapy apparatus To measure the displacement of the X-ray from the center position:
Process (1)
From the irradiation image information obtained by irradiating the X-ray absorber to the X-ray absorber from the gantry, the actual isocenter position by the therapeutic X-ray and the X-ray absorber arranged at the virtual isocenter A step of measuring a displacement from the position of the step, and a step (2)
From the irradiation image information obtained by irradiating the X-ray absorber to the X-ray absorber from the diagnostic X-ray imaging apparatus, the X-ray absorption arranged at the center position of the diagnostic X-ray and the virtual isocenter This can be solved by measuring the displacement from the body position.

In a preferred embodiment of the measurement method according to the present invention, the position determining laser beam comprises an X axis direction position determining laser beam, a Y axis direction position determining laser beam, and a Z axis direction position determining laser beam, These position-determining laser beams are emitted from a position-determining laser beam irradiating means provided on the ceiling and side walls in the radiotherapy room in a single plane and orthogonal to each other.
In another preferable aspect of the measurement method according to the present invention, irradiation image information obtained by irradiating the X-ray absorber from the gantry to the X-ray absorber is displayed on a passage extending from the gantry through the X-ray absorber. It is acquired by the image collecting means provided in.
In still another preferred aspect of the measurement method according to the present invention, the diagnostic X-ray imaging apparatus uses irradiation image information obtained by irradiating diagnostic X-rays on the X-ray absorber from the diagnostic X-ray imaging apparatus. It is acquired by a diagnostic X-ray detection unit provided on a path extending from the diagnostic X-ray irradiation unit through the X-ray absorber.

  In the present invention, any one of a virtual isocenter, an actual isocenter, or a center position of a diagnostic X-ray is selected as an adjustment reference point, and the steps (1) and (2) according to claim 1 are selected. ) Is used to move two points other than the selected adjustment reference point so as to coincide with the adjustment reference point, and to move the virtual isocenter, the actual isocenter, and the diagnostic X It also relates to an adjustment method for matching the center position of the line.

  Further, according to the present invention, one of the virtual isocenter, the actual isocenter, or the center position of the diagnostic X-ray is selected as an adjustment reference point, and two of the two points other than the selected adjustment reference point are selected. The first movement point is the first movement point and the other one point is the second movement point, and the displacement obtained by carrying out one of the steps (1) or (2) according to claim 1 Using the measured value, the first moving point is moved so as to coincide with the adjustment reference point, and then the step (1) or the other step (2) according to claim 1 is performed. Using the obtained displacement measurement value, the second moving point is moved so as to coincide with the adjustment reference point, and the virtual isocenter, the actual isocenter, and the center position of the diagnostic X-ray are made to coincide with each other. Also related to the method.

In a preferred embodiment of the adjustment method according to the present invention, the movement of the virtual isocenter is performed by adjusting the laser beam irradiation means for position determination provided on the wall surface in the radiotherapy room, and the actual movement of the isocenter is performed by the radiotherapy apparatus. The center position of the diagnostic X-ray is moved by adjusting the diagnostic X-ray imaging apparatus provided in the radiation therapy apparatus.
In another preferred embodiment of the adjustment method according to the present invention, the actual isocenter is selected as the adjustment reference point.
In still another preferred embodiment of the adjustment method according to the present invention, the actual isocenter is selected as the adjustment reference point, the virtual isocenter is selected as the first movement point, and the center position of the diagnostic X-ray is set as the second movement point. Select as

Further, the present invention provides a virtual isocenter determined by a position determining laser beam irradiated from a wall surface in a radiation therapy room, inside a displacement measurement phantom placed on a treatment table in the radiation therapy room. The displacement measurement phantom is fixed at a position where the embedded X-ray absorbers coincide with each other, and the gantry of the radiotherapy apparatus is positioned at the topmost position when the gantry rotating means rotates the isocenter as the rotation center. Subsequently, the therapeutic X-ray is drawn from the irradiation image information after the therapeutic X-ray is irradiated in the vertical direction toward the floor surface from the gantry located at the top and the X-ray absorber is irradiated. It also relates to a method of measuring the displacement between the trajectory and the rotation axis of the treatment table rotating disk.
Further, using the measurement result of the displacement obtained in the measurement method, the therapeutic X-rays irradiated from the gantry positioned at the topmost when the isocenter is rotated about the rotation center by the gantry rotating means The present invention also relates to a method of adjusting the displacement between the drawn locus and the rotation axis of the treatment table rotating disk.

  In still another preferred aspect of the adjustment method according to the present invention, the displacement measurement result obtained in the measurement method is used to move the treatment table of the radiotherapy device, thereby fixing the treatment table on the treatment table. The target treatment site of the patient is matched with the actual isocenter position by the therapeutic X-ray.

  Furthermore, the present invention provides a therapeutic X-ray irradiated from a gantry of a radiotherapy apparatus using a virtual isocenter using a laser beam for determining a position of the radiotherapy room and a diagnostic X-ray imaging apparatus of the radiotherapy apparatus. It also relates to a control system that controls the movement of the treatment table so that the actual isocenter position of the patient and the treatment target diseased part of the patient placed on the treatment table in the radiotherapy room coincide with each other.

  Furthermore, the present invention provides a virtual isocenter determined by an actual isocenter position by a therapeutic X-ray irradiated from a gantry of a radiotherapy apparatus and a positioning laser beam irradiated from a wall surface in the radiotherapy room. The displacement between the position and the center position of the diagnostic X-ray irradiated from the diagnostic X-ray imaging apparatus is measured by irradiating the X-ray absorber from the diagnostic X-ray imaging apparatus with the diagnostic X-ray. Also related to the phantom for.

  In the measurement method of the present invention, the actual isocenter of the therapeutic X-ray, the virtual isocenter by the position determining laser beam, and the center position of the diagnostic X-ray emitted from the diagnostic X-ray imaging apparatus match. The inspection of whether or not it is possible can be easily performed.

  The adjustment method of the present invention uses the displacement measurement value obtained by the measurement method, the actual isocenter of the therapeutic X-ray, the virtual isocenter by the positioning laser beam, and the diagnostic X-ray imaging apparatus The center position of the diagnostic X-rays emitted from can be matched.

  The displacement measuring phantom of the present invention can be used in the measuring method and the adjusting method.

It is a typical perspective view of a radiotherapy apparatus. It is a typical perspective view which shows the state of the patient after attaching the skin mark. It is a typical perspective view which shows the patient of the state which made the skin mark and the laser beam for position determination correspond. 1 is a schematic perspective view of a displacement measurement phantom according to the present invention. FIG. It is a typical partial enlarged view of the position detection part used for the phantom for displacement measurement by this invention. FIG. 6 is a schematic partial enlarged view showing a part of the position detection unit of FIG. It is a typical side view which cuts and shows a part of holding board part used for the phantom for displacement measurement by the present invention. It is a typical perspective view which shows the use condition of the phantom for a displacement measurement by this invention. It is a figure for demonstrating the method to make the laser beam for position determination and the laser beam absorption band for position determination correspond in the case where the laser beam absorption area for deviation detection is not provided. It is a figure for demonstrating the method to make the laser beam for position determination and the laser beam absorption band for position determination correspond in the case of providing the laser beam absorption area for deviation detection. It is a typical perspective view which shows the displacement measuring method and displacement adjusting method in the radiotherapy apparatus shown in FIG.

First, an example of a preferred embodiment of the displacement measurement phantom used in the measurement method of the present invention will be described with reference to FIGS.
FIG. 4 is a schematic perspective view of the displacement measurement phantom 10, and the displacement measurement phantom 10 includes a position detection unit 1 and a holding plate unit 2. FIG. 5 is a schematic partial enlarged view of the position detection unit 1, FIG. 6 is a schematic partial enlarged view showing a part of the position detection unit 1, and FIG. It is a typical side view which cuts and shows a part.

As shown in FIGS. 4 to 7, the position detection unit 1 of the displacement measurement phantom 10 is fixed to the upper surface of the holding plate unit 2, and is a holding rod made of an X-ray absorber 11 and an X-ray transmissive material. The X-ray absorber 11 is embedded in the X-ray transmissive holding rod portion 12.
On the surface of the X-ray transmissive holding bar portion 12, a laser beam absorption band 14 for position determination and a laser beam absorption region 16 for displacement detection are provided.
The holding rod portion 12 of the position detecting portion 1 is fixed to the holding disc portion 2 on one end side of the rod-like body, and the other end portion is protruded from the holding disc portion 2, and a free tip portion It is preferable to have.

The X-ray absorber 11 is made of a material that absorbs therapeutic X-rays and diagnostic X-rays.
The material of the X-ray absorber 11 is not limited as long as it is a material that can absorb X-rays, but tungsten is preferable because of its high X-ray absorption ability.
The shape of the X-ray absorber 11 is not particularly limited as long as the position can be specified, but a spherical shape as shown in FIGS. 4 to 7 is preferable, and an X-ray image is absorbed and projected. The position can be measured from the center of the round circle. The size of the X-ray absorber 11 is not particularly limited as long as the position can be specified. For example, in the case of a spherical X-ray absorber, the diameter is preferably 2 mm to 10 mm, more preferably 3 mm to 5 mm. .

  As shown in FIG. 4, the position of the X-ray absorber 11 in the holding bar portion 12 needs to be a position where the X-ray path is not obstructed by the holding plate portion 2 when forming an X-ray image. As long as it is not obstructed by the part 2, it may be arranged at the center position of the holding bar part 12 or at a rear position close to the holding board part 2, but from the viewpoint of easy displacement (displacement) detection operation, the holding board part 2 It is preferable to arrange at a portion protruding from the end, particularly at the free tip of the holding rod 12.

  Since it is ideal that only the X-ray absorber 11 included in the holding rod portion 12 absorbs the therapeutic X-ray and the diagnostic X-ray as the material of the holding rod portion 12, the therapeutic X-ray and the diagnostic X-ray are used. It must be transparent to the line. Moreover, it is necessary to embed and contain the X-ray absorber 11 inside. Accordingly, various transparent synthetic resins (for example, acrylic resins) are preferable, and transparent glass and the like are also preferable in terms of X-ray transparency and ease of visual confirmation of the embedding operation.

  As for the shape of the holding bar 12, the X-ray absorber 11 can be embedded therein, and a laser beam absorption band for position determination and a laser beam absorption region for detecting displacement described later are provided on the side surface. It is not limited as long as the shape can be adjusted. Therefore, it is not limited to a regular quadrangular column (a square column having a square cross section) as shown in FIGS. 4 to 7, and may be, for example, a cylinder or a quadrangular column (including a rectangular column having a rectangular cross section).

The position determination laser light absorption band 14 includes an X-axis direction position determination laser light absorption band 14a, a Y-axis direction position determination laser light absorption band 14b, and a Z-axis direction position determination laser light absorption band 14c.
The laser beam absorption band 14a for determining the X-axis direction position is provided as a straight line continuous to each other at the center in the width direction of each of the upper surface 12U, the front end surface 12T, and the lower surface 12D of the holding rod 12 having a square prism shape. And the straight lines of the lower surface 12D are parallel to each other.
The laser beam absorption band 14b for determining the Y-axis direction position is provided as straight lines that are continuous to each other in the center in the width direction of the left side surface 12L, the front end surface 12T, and the right side surface 12R of the regular quadratic columnar holding rod portion 12, The straight lines of the left side surface 12L and the right side surface 12R are parallel to each other. The X-axis direction position determining laser light absorption band 14 a and the Y-axis direction position determining laser light absorption band 14 b are orthogonal to each other at the center point of the front end surface 12 T of the holding rod portion 12.
The laser beam absorption bands 14c for determining the position in the Z-axis direction are parallel to the four sides of the front end surface 12T on the upper surface 12U, the left side surface 12L, the lower surface 12D, and the right side surface 12R of the regular quadrangular columnar holding rod portion 12, respectively. The straight lines of the upper surface 12U and the lower surface 12D are parallel to each other, and the straight lines of the left side surface 12L and the right side surface 12R are parallel to each other. The straight line between the upper surface 12U and the lower surface 12D is orthogonal to the straight line of the X-axis direction position determination laser light absorption band 14a, and the straight line between the left side surface 12L and the right side surface 12R is the Y-axis direction position determination laser light absorption band 14b. Orthogonal to the straight line. The distance between the laser beam absorption band 14c for determining the Z-axis direction position and the front end face 12T is not particularly limited. For example, as shown in FIGS. 4 to 7, 1 / of the length of each side of the front end face 12T. 2 can be used.

As shown in FIGS. 5 and 6, the position determining laser light absorption band 14 (14 a, 14 b, 14 c) indicates the position of the X-ray absorber 11 embedded in the holding rod portion 12. It is provided to show.
Specifically, as shown in FIG. 6, a cross section formed by cutting the holding rod portion 12 along the X-axis direction position determination laser light absorption band 14a and a Y-axis direction position determination laser light absorption band 14b The intersection of the cross section formed by cutting the holding rod portion 12 along the cross section formed by cutting the holding rod portion 12 along the laser beam absorption band 14c for determining the Z-axis direction position is the center of the X-ray absorber 11. Position determining laser light absorption bands 14 (14a, 14b, 14c) are provided so as to completely coincide with the positions.

  Position determining laser light absorption bands 14 (14a, 14b, 14c) provided on the side surfaces of the holding rod portion 12 are position determining laser beams 35 (35a, 35b) irradiated from the wall surfaces (ceiling and side surfaces) in the radiation treatment room. , 35c). Specifically, the linear image drawn on the side surface of the holding rod portion 12 by the X-axis direction position determining laser beam 35a and the X-axis direction position determining laser beam absorption band 14a are matched to determine the Y-axis direction position. The linear image drawn by the laser beam 35b on the side surface of the holding rod portion 12 is matched with the laser beam absorption band 14b for determining the Y-axis direction position, and the laser beam 35c for position determination in the Z-axis direction is applied to the side surface of the holding rod portion 12. By matching the drawn linear image with the Z-axis direction position determination laser light absorption band 14c, the position of the virtual isocenter by the position determination laser light 35 (35a, 35b, 35c) and the holding rod portion 12 The position of the X-ray absorber 11 embedded inside can be matched.

  The width of the position determining laser light absorption band 14 is for the purpose of confirming a certain coincidence with the linear image of the position determining laser light 35, so that the linear image drawn by the position determining laser light 35 The width (generally 1 mm) is preferably substantially the same, and is extremely thin. Accordingly, the width of the position determining laser light absorption band 14 varies depending on the width of the linear image drawn by the position determining laser light 35 used, but is generally 0.5 to 1.5 mm, particularly 1 mm.

  In the phantom 10 of the present invention, since the holding rod portion 12 of the position detection unit 1 is made of an X-ray transmissive material, it is normally transparent and transmits laser light without absorbing it. Therefore, the position-determining laser light absorption band 14 provided on the side surface of the holding rod portion 12 needs to be formed of a material that absorbs the laser light (that is, the position-determining laser light 35) and can be observed with the naked eye. As the laser light-absorbing material (preferably, an X-ray transmitting material), a known material can be used, and it can be formed by applying to the side surface of the holding rod portion 12 by a known method. Alternatively, a linear groove may be provided on the side surface of the holding rod portion 12, and the laser beam absorbing band 14 for position determination may be formed by filling the groove with a laser light absorbing material.

  In the phantom 10 of the present invention, the holding rod portion 12 of the position detection portion 1 can further be provided with a laser beam absorption region 16 for detecting displacement. The deviation detection laser light absorption region 16 is at least one of an X axis direction deviation detection laser light absorption region 16a, a Y axis direction deviation detection laser light absorption region 16b, and a Z axis direction deviation detection laser light absorption region 16c. Provide one, preferably all. The displacement detection laser light absorption region 16 intersects (preferably orthogonally) the position determination laser light absorption band 14. Similarly to the position determination laser light absorption band 14, the displacement detection laser light absorption region 16 needs to be formed of a material that absorbs laser light (that is, the position determination laser light 35) and can be observed with the naked eye. is there. As the laser light-absorbing material (preferably, an X-ray transmitting material), a known material can be used, and it can be formed by applying to the side surface of the holding rod portion 12 by a known method. In addition, a linear groove may be provided on the side surface of the holding rod portion 12, and the groove may be filled with a laser light absorbing material to form the laser beam absorption region 16 for detecting the displacement.

The displacement detection laser light absorption region 16 is a line drawn on the side surface of the holding rod portion 12 by the position determination laser light absorption band 14 (14a, 14b, 14c) and the position determination laser light 35 (35a, 35b, 35c). It is used for facilitating the operation of matching the image with the entire length of one side surface of the position determining laser light absorption band 14.
For example, if the linear image drawn on the side surface of the holding rod portion 12 by the X-axis direction position determining laser beam 35a and the X-axis direction position determining laser beam absorption band 14a do not match, as shown in FIG. Since the laser beam is absorbed only at the intersection E, and the laser beam is transmitted at other locations, it is difficult or impossible to determine the direction and degree of deviation between the two lines.

  On the other hand, when the laser beam absorption region 16a for detecting the X-axis direction deviation is also provided, as shown in FIG. 10, the position determining laser beam 35a is also at the intersections F and G with the laser beam absorption region 16a for detecting the axial direction deviation. Since the position determination laser beam 35a is absorbed and can be observed at the three intersections E, F, and G, it is possible to easily determine the direction and degree of deviation between the two lines. The entire length direction of the laser beam absorption band 14 (14a, 14b, 14c) and the entire linear image drawn by the position determining laser beam 35 (35a, 35b, 35c) on the side surface of the holding rod portion 12 In addition, an operation of matching the entire length of one side surface of the position determining laser light absorption band 14 can be easily performed.

  Accordingly, the position where the deviation detecting laser light absorption region 16 is provided is not particularly limited as long as it can easily determine the direction and degree of deviation between the two lines. For example, FIGS. As shown in FIG. 5, at least one end, preferably both ends, of the position determining laser light absorption band 14 provided on each side surface of the holding rod 12 crosses the position determining laser light absorption band 14 (preferably orthogonal). It can be provided as a strip or a linear body.

  In the phantom of the present invention, since the X-ray transmissive holding rod 12 is made of a transparent acrylic resin or the like, the X-ray absorber 11 included in the position detector 1 is embedded in the position detector 1. It can be clearly observed from the outside with the naked eye. Further, the ridge line on the side opposite to the observing side, the laser beam absorption band for position determination and the laser beam absorption region for displacement detection provided on the side surface on the opposite side can be confirmed with the naked eye. However, in FIGS. 4, 5, 7, and 8, for the purpose of facilitating understanding of the structure of the position detection unit 1, the holding rod 12 is illustrated as being formed of an opaque material. In addition, the ridge line on the opposite side that can be visually observed, the laser beam absorption band for position determination and the laser beam absorption region for deviation detection provided on the side surface on the opposite side are not shown. Further, the X-ray absorber 11 is illustrated by a dotted line for the purpose of facilitating understanding of its position.

In the phantom of the present invention, the holding platen portion 2 can include a base plate 21, fine adjustment means 23, and a weight 25 as shown in FIG.
The base board 21 has a bottom surface that can be placed on the treatment table of the radiotherapy apparatus, and holds fine adjustment means 23 on the upper surface side. The fine adjustment means 23 also functions as a connection connection means between the position detection unit 1 and the holding plate part 2, and can include a weight 25.

The fine adjustment means 23 includes a fine adjustment part base board 23d, which is a specific connection and connection means between the position detection part 1 and the holding board part 2. On the fine adjustment part base board 23d, for example, a first height The height adjusting unit 23a, the second height adjusting unit 23b, and the third height adjusting unit 23c may be included.
The fine adjustment means 23 finely adjusts the height of the position detection unit 1, while the position determination laser light absorption band 14 (14 a, 14 b, 14 c) provided in the position detection unit 1 and the position determination laser light 35 ( 35a, 35b, and 35c). As shown in FIG. 7, the fine adjustment means 23 can be composed of a rotating screw. The fine adjustment unit base board 23d may be provided with horizontal adjustment means (not shown).
When fine adjustment is not necessary, the position detecting unit 1 can be directly held on the base board 21 without providing the fine adjustment means 23.
The weight 25 is obtained by aligning the position determining laser light absorption band 14 (14a, 14b, 14c) with the position determining laser light 35 (35a, 35b, 35c), and then the displacement measuring phantom 10 from the place. Provided when it is necessary not to move easily.

Next, representative aspects of the displacement measuring method and displacement adjusting method of the present invention implemented using the displacement measuring phantom will be described with reference to FIG.
FIG. 11 is a perspective view schematically illustrating a case where the displacement measurement method and the displacement adjustment method of the present invention are implemented using the radiotherapy apparatus 4 shown in FIG.

  Usually, in the radiotherapy room in which the radiotherapy apparatus 4 is installed, a treatment table rotating plate 57 for rotating the treatment table 46 is provided on the floor surface, and the treatment table rotating plate 57 is rotated. As shown by an arrow A in FIG. 11, the center 53 can be rotated in both directions (clockwise or counterclockwise) with respect to a rotation axis extending vertically upward from the floor surface to the ceiling direction. Can be stationary and fixed at a rotation angle.

  Further, since the treatment table 46 in the radiation therapy room is connected to the treatment table rotation plate 57 and the treatment table holding frame 59, the treatment table 46 and the treatment table rotation plate 57 can be rotated integrally. The treatment table 46 can rotate in both directions (clockwise or counterclockwise) around the rotation center 53 in parallel with the floor surface, and can be fixed stationary at an arbitrary rotation position. The treatment table 46 includes a position adjusting means (not shown) for moving the treatment table 46 in a direction away from or close to the rotation axis (direction B) parallel to the floor surface, and the treatment table 46 on the floor surface. Position adjustment means (not shown) for raising or lowering in the vertical direction (C direction) is also provided.

  When the radiotherapy apparatus 4 is first installed in the radiotherapy room, therapeutic X-rays that completely coincide with the rotation axis 55 of the treatment table rotating plate 57 provided on the floor surface of the radiotherapy room are transferred from the gantry 41. The radiation therapy apparatus 4 is installed at a position where irradiation is possible. That is, the gantry 41 of the radiation therapy apparatus 4 can be rotated 360 ° around the isocenter by the gantry rotating means 42, but the gantry 41 is positioned at the topmost position and vertically directed toward the floor surface. When the therapeutic X-ray is irradiated in the direction, the radiotherapy apparatus 4 is placed in the radiation therapy room so that the locus drawn by the therapeutic X-ray completely coincides with the rotation axis 55 of the treatment table rotating plate 57. Install in. Alternatively, it can be installed without matching, but in that case, the X-ray trajectory irradiated in the vertical direction from the gantry 41 located at the top to the floor and the treatment table rotating plate 57 It is necessary to accurately measure the deviation of the rotation axis 55 and adjust the position of the isocenter and the treatment table 46 based on the deviation. In addition, after the radiotherapy apparatus 4 is installed in the radiotherapy room so as to satisfy the above-described conditions, the radiotherapy apparatus 4 and the rotary shaft 55 are initially placed under the influence of vibrations such as repeated driving operations and earthquakes. The displacement can also be detected by using the displacement phantom. This point will be described later.

  When the radiotherapy apparatus 4 is first installed in the radiotherapy room, the intersection of the laser beam for position determination (virtual isocenter) and the isocenter (the actual isocenter) by the therapeutic X-ray are accurately determined. Install to match. That is, the wall surface (that is, the ceiling or the side wall surface) in the radiotherapy room is provided with irradiation means (not shown) for position determination laser light, and the position in the X-axis direction irradiated from these irradiation means is determined. It is necessary to use, as a virtual isocenter, a point where the laser beam 35a for laser beam, the laser beam 35b for position determination in the Y-axis direction, and the laser beam 35c for position determination in the Z-axis direction intersect. Since it is necessary to exactly match the isocenter by line (actual isocenter), the radiotherapy apparatus 4 is installed in the radiotherapy room so as to satisfy this condition. Even if this condition is satisfied at the beginning of the installation, the virtual isocenter may deviate from the actual isocenter due to the influence of subsequent driving operations or vibrations such as earthquakes. Such a shift is generally desired to be suppressed within 1 mm. According to the present invention, the displacement can be accurately detected using the displacement measuring phantom, and the displacement can be accurately corrected.

  In the radiotherapy apparatus 4 including the diagnostic X-ray imaging apparatus 44, the diagnostic X-ray imaging is performed so that the center of the diagnostic X-ray beam bundle and the actual isocenter of the therapeutic X-ray coincide with each other accurately. A device 44 is attached. However, the center of the diagnostic X-ray beam bundle and the actual isocenter of the therapeutic X-ray may be shifted due to repeated driving operations or vibrations such as earthquakes. It is possible to detect the above-mentioned deviation accurately.

Each of the methods for detecting each displacement (displacement) using the displacement measurement phantom and correcting and adjusting the displacement as necessary includes the following steps (1) to (3).
(1) displacement detection step;
(2) If necessary, a displacement correction step, and (3) preferably a correction confirmation step.
As will be described later, displacement (displacement) is detected, and the displacement of the treatment table is controlled using the measured value of the displacement without correcting or adjusting the displacement. Can also be matched.

The detection / adjustment method regarding the displacement (deviation) between the actual isocenter and the virtual isocenter includes, for example, the following steps (A) to (E).
(A) Displacement Measurement Phantom Placement Step This step is a step of placing the displacement measurement phantom 10 on the treatment table 46 of the radiation therapy apparatus, and the X-ray absorber 11 included in the displacement measurement phantom 10. It is preferable to place the sensor so that the position substantially coincides with the virtual isocenter. At that time, as shown in FIG. 11, the X-ray for treatment irradiated from the gantry 41 is projected from the treatment table end 47 by projecting the free tip of the holding rod 12 including the X-ray absorber 11 embedded therein, It is preferable to arrange so as not to contact the treatment table 46.

(B) Step of matching virtual isocenter and X-ray absorber In this step, the displacement measurement phantom 10 placed on the treatment table 46 is placed on the wall surface in the radiation treatment room (that is, the ceiling or the side wall surface). ) Is irradiated with the position determining laser beam 35, and the virtual isocenter determined by the position determining laser beam 35 is matched with the position of the X-ray absorber 11. At this time, the irradiation means of the position determining laser beam 35 is not moved, but the treatment table 46 on which the displacement measurement phantom 10 is placed is moved, or the displacement measurement phantom 10 is moved on the treatment table 46. Alternatively, the position of the X-ray absorber 11 is moved by combining the movement of the treatment table 46 and the movement of the phantom 10. The fine adjustment by the fine adjustment means 23 can be appropriately combined.

(C) Displacement measurement process between virtual isocenter and actual isocenter In this process, the gantry 41 of the radiotherapy apparatus is rotated, and therapeutic X-rays are applied to the X-ray absorber 11 from various directions (positions). Irradiated to obtain irradiation image information (for example, X-ray image or image signal), and the X-ray absorber 11 disposed at the correct position of the virtual isocenter and the therapeutic X-ray actually irradiated from the gantry The displacement (deviation) from the actual isocenter formed by is measured. Irradiation image information is acquired by the image collection means 48. The image collecting means 48 is provided on a path where the therapeutic X-rays irradiated from the gantry pass through the isocenter and travel along the extension line. Since the gantry 41 is rotated 360 ° by the gantry rotating means 42 with the isocenter as the rotation center, the image collecting means 48 is also rotated 360 ° on the opposite side of the isocenter. Irradiation image information is acquired, for example, every 45 ° or 90 °.

(D) Virtual Isocenter Correction Step This step is performed when the virtual isocenter and the actual isocenter are misaligned. Since the deviation between the two is accurately measured by the X-ray irradiation image information, one of the positions is moved based on the measurement result. It is preferable to move the position of the virtual isocenter for ease of adjustment operation. The position of the virtual isocenter can be implemented by adjusting the irradiation direction of the position determining laser beam irradiation means provided on the wall surface in the radiotherapy room.

(E) Confirmation process of correction It is preferable to confirm the correction by the said process (D). In this step (E), the step (A) “displacement measurement phantom placement step” and the step (B) “virtual isocenter and X-ray absorber are made to coincide with the corrected virtual isocenter. The same operation as the “process” and the step (C) “displacement measurement process between the virtual isocenter and the actual isocenter” is performed, and there is no displacement (displacement) between the virtual isocenter and the actual isocenter. It is to confirm.

  When the above steps (A) to (E) are performed, the virtual isocenter and the actual isocenter coincide with each other accurately, so that the position is determined from the wall surfaces (ceiling and side surfaces) in the radiation therapy room as shown in FIG. The patient 3 is irradiated with the laser beam 35 for treatment, and the treatment table 46 is moved so that the laser beams 35a, 35b, and 35c for position determination coincide with the skin mark 31, and the treatment table 46 is fixed at a completely coincident point. Thus, the treatment target diseased part 33 and the isocenter (actual isocenter) can be matched.

  After carrying out the steps (A) and (B) and detecting displacement (deviation), the displacement of the treatment table is controlled using the measured value of the displacement without correcting or adjusting the displacement, It is also possible to match the patient's treated area with the actual isocenter. That is, as shown in FIG. 3, the patient 3 is irradiated with the positioning laser beam 35 from the wall surfaces (ceiling and side surfaces) in the radiation therapy room, and the positioning laser beams 35 a, 35 b, and 35 c coincide with the skin mark 31. The treatment table 46 is moved as described above, and the treatment table 46 is stopped at a completely coincident point. Subsequently, the treatment table 46 is moved according to the measurement values obtained by the steps (A) and (B). The treatment target affected part 33 and the isocenter (actual isocenter) can be matched. When using a control system including a program for controlling the movement of the treatment table, the displacement measurement results obtained by the steps (A) and (B) are introduced into the program, and the control system is used. The treatment table 46 can be moved so that the treatment target affected area 33 and the isocenter (actual isocenter) coincide with each other.

  Next, a detection / adjustment method relating to the deviation between the center of the diagnostic X-ray beam bundle and the actual isocenter 71 will be described. This method can be performed before or after performing the displacement measurement between the virtual isocenter and the actual isocenter and optionally performing the displacement adjustment. Moreover, when it implements after the displacement measurement of a virtual isocenter and an actual isocenter, it can implement before a displacement adjustment process, or it can implement after the displacement adjustment process. In the following, a description will be given of a preferred embodiment implemented after performing the displacement measurement and displacement adjustment process between the virtual isocenter and the actual isocenter.

(A) Displacement measurement phantom placement step This step is a step of placing the displacement measurement phantom 10 on a treatment table 46 of a radiation therapy apparatus, and the X-ray absorber 11 included in the displacement measurement phantom 10. It is preferable to place the sensor so that the position substantially coincides with the virtual isocenter. At this time, as shown in FIG. 11, the free distal end portion of the holding rod portion 12 including the X-ray absorber 11 embedded is projected from the treatment table end portion 47, and the diagnosis irradiated from the diagnostic X-ray irradiation portion 44a. It is preferable that the medical X-rays are arranged so as not to contact the treatment table 46.

(B) The step of matching the virtual isocenter and the X-ray absorber In this step, the wall surface in the radiation treatment room (that is, the ceiling or the side wall surface) with respect to the displacement measurement phantom 10 placed on the treatment table 46 ) Is irradiated with the position determining laser beam 35, and the virtual isocenter determined by the position determining laser beam 35 is matched with the position of the X-ray absorber 11. At this time, the irradiation means of the position determining laser beam 35 is not moved, but the treatment table 46 on which the displacement measurement phantom 10 is placed is moved, or the displacement measurement phantom 10 is moved on the treatment table 46. Alternatively, the position of the X-ray absorber 11 is moved by combining the movement of the treatment table 46 and the movement of the phantom 10. The fine adjustment by the fine adjustment means 23 can be appropriately combined. If the virtual isocenter is accurately matched with the actual isocenter in advance, the X-ray absorber 11 and the actual isocenter are exactly matched by this process.

(C) Diagnostic X-ray imaging process In this process, the diagnostic X-ray imaging apparatus 44 of the radiotherapy apparatus is rotated around the isocenter, and diagnostic X-rays are transmitted from various directions (positions) to the X-ray absorber 11. The X-ray absorber 11 is obtained by irradiating the image with the irradiation image information (for example, X-ray image or image signal), and is accurately arranged at the position of the actual isocenter (= virtual isocenter). The displacement (deviation) from the center of the diagnostic X-ray beam bundle irradiated from the X-ray irradiation unit 44a is measured. Irradiation image information is acquired by the diagnostic X-ray detection unit 44b. The diagnostic X-ray detection unit 44b is provided on a path where the diagnostic X-rays emitted from the diagnostic X-ray irradiation unit 44a pass through the isocenter and travel along the extension line. The diagnostic X-ray irradiating unit 44a and the diagnostic X-ray detecting unit 44b constituting the diagnostic X-ray imaging apparatus 44 are arranged on opposite sides of the isocenter that is the rotation center, and the diagnostic X-ray imaging apparatus 44 is disposed. Is rotated 360 ° by the gantry rotating means 42 with the isocenter as the rotation center, so that the diagnostic X-ray irradiation unit 44a and the diagnostic X-ray detection unit 44b rotate 360 ° on opposite sides of the isocenter, respectively. Irradiation image information is acquired, for example, every 45 ° or 90 °.
(D) Correction process of diagnostic X-ray imaging apparatus This process is performed when the center of the diagnostic X-ray beam bundle and the actual isocenter (= virtual isocenter) deviate from each other. To do. Since the deviation between the two is accurately measured by the irradiation image information, the position of the diagnostic X-ray imaging apparatus is moved based on the measurement result.

(E) Modification confirmation step It is preferable to confirm the modification in the step (d). In this step (e), for the diagnostic X-ray imaging apparatus after correction, the step (b) “displacement measurement phantom placement step”, the step (b) “virtual isocenter and X-ray absorber, And the process (c) “diagnostic X-ray imaging process”, the center of the diagnostic X-ray beam bundle and the actual isocenter (= This confirms that there is no displacement (displacement) in the (virtual isocenter).

  After the virtual isocenter and the actual isocenter are matched, when the steps (a) to (e) are performed, the center of the diagnostic X-ray beam bundle and the actual isocenter exactly match, As shown in FIG. 3, the patient 3 is irradiated with the position determination laser beam 35, and the treatment table 46 is moved so that the position determination laser beams 35a, 35b, and 35c coincide with the skin mark 31. The treatment target affected area 33 and the isocenter (actual isocenter) can be matched by simply fixing the treatment table 46 at the point.

  The position determining laser light irradiation means provided on the wall surface of the radiotherapy room is relatively prepared for position adjustment, but the position adjustment of the radiotherapy apparatus 4 is generally very difficult. In many cases, the position adjusting means of the diagnostic X-ray imaging apparatus 44 is not provided. In such a case, it is practically difficult to completely match the three points even when a displacement is confirmed between the actual isocenter, the virtual isocenter, and the center of the diagnostic X-ray beam bundle. It is preferable to adjust the position of the virtual isocenter so that the error of the three points is within the range of 1 mm. Further, when it is difficult to keep the error of three points within a range of 1 mm or less, it is preferable to adjust the position of the radiation therapy apparatus 4 or the position of the diagnostic X-ray imaging apparatus 44.

  After detecting the displacement (deviation) by carrying out the above steps (a) and (b), the displacement of the treatment table is controlled using the measured value of the displacement without correcting or adjusting the displacement, It is also possible to match the patient's treated area with the actual isocenter. That is, as shown in FIG. 3, the patient 3 is irradiated with the positioning laser beam 35 from the wall surfaces (ceiling and side surfaces) in the radiation therapy room, and the positioning laser beams 35 a, 35 b, and 35 c coincide with the skin mark 31. When the treatment table 46 is moved as described above, the treatment table 46 is stopped at a completely coincident point, and then the treatment table 46 is moved according to the measurement values obtained by the steps (a) and (b). The treatment target affected part 33 and the isocenter (actual isocenter) can be matched. In the case of using a control system including a program for controlling the movement of the treatment table, the displacement measurement results obtained by the above steps (a) and (b) are introduced into the program, so that The treatment table 46 can be moved so that the treatment target affected area 33 and the isocenter (actual isocenter) coincide with each other.

Next, a method for detecting and correcting / adjusting the displacement (displacement) between the rotation shaft 55 of the treatment table turntable 57 and the therapeutic X-ray will be described.
This method includes, for example, the following steps (a) to (e).

(A) Displacement Measurement Phantom Placement Step This step is a step of placing the displacement measurement phantom 10 on the treatment table 46 of the radiation therapy apparatus, and the X-ray absorber 11 included in the displacement measurement phantom 10. It is preferable to place the sensor so that the position substantially coincides with the virtual isocenter. At that time, as shown in FIG. 11, the X-ray for treatment irradiated from the gantry 41 is projected from the treatment table end 47 by projecting the free tip of the holding rod 12 including the X-ray absorber 11 embedded therein, It is preferable to arrange so as not to contact the treatment table 46.

(B) Step of matching virtual isocenter and X-ray absorber In this step, the wall surface (that is, the ceiling or the side wall surface) in the radiation treatment chamber with respect to the displacement measurement phantom 10 placed on the treatment table 46 ) Is irradiated with the position determining laser beam 35, and the virtual isocenter determined by the position determining laser beam 35 is matched with the position of the X-ray absorber 11. At this time, the irradiation means of the position determining laser beam 35 is not moved, but the treatment table 46 on which the displacement measurement phantom 10 is placed is moved, or the displacement measurement phantom 10 is moved on the treatment table 46. Alternatively, the position of the X-ray absorber 11 is moved by combining the movement of the treatment table 46 and the movement of the phantom 10. The fine adjustment by the fine adjustment means 23 can be appropriately combined.

(C) Displacement measuring step of rotation axis and therapeutic X-ray In this step, with the gantry 41 positioned at the top, the treatment table 46 in the radiotherapy room is rotated and positioned at the top. The X-ray absorber 11 is irradiated with therapeutic X-rays from the gantry to obtain irradiation image information (for example, an X-ray image or an image signal), and the rotating shaft 55 of the treatment table rotating plate 57 and the gantry actually. Measure the displacement (deviation) from the therapeutic X-rays irradiated from. Irradiation image information is acquired by the image collection means 48. The image collecting means 48 is provided on a path where the therapeutic X-rays irradiated from the gantry pass through the isocenter and travel along the extension line. The treatment table 46 rotates 180 ° about the rotation shaft 55 as a rotation center. Irradiation image information is acquired for every 45 degrees of rotation angles, for example.

(D) Rotating shaft correcting step This step is performed when the rotating shaft 55 of the treatment table rotating disk 57 and the therapeutic X-ray are misaligned. Since the deviation between the two is accurately measured by the X-ray irradiation image information, the position of either the rotary shaft 55 or the therapeutic X-ray (isocenter) is moved based on the measurement result.

(E) Modification Confirmation Step It is preferable to confirm the modification in the step (d). In this step (e), the step (a) “displacement measurement phantom placement step” and the step (b) “virtual isocenter and X-ray absorber are matched with respect to the corrected rotation axis. And the same operation as the step (c) “displacement measurement process between the rotation axis and the therapeutic X-ray”, and confirms that there is no displacement between the rotation axis and the therapeutic X-ray. It is.

  The measurement method, the adjustment method, and the displacement measurement phantom according to the present invention are based on an actual isocenter of a therapeutic X-ray, a virtual isocenter by a positioning laser beam, and a diagnostic X-ray imaging apparatus in a radiotherapy apparatus. It can be used to measure the displacement (deviation) from the center position of the irradiated diagnostic X-ray and adjust the displacement.

DESCRIPTION OF SYMBOLS 1 ... Position detection part; 2 ... Holding board part; 3 ... Patient; 4 ... Radiotherapy apparatus;
DESCRIPTION OF SYMBOLS 10 ... Displacement measurement phantom; 11 ... X-ray absorber; 12 ... Holding rod part;
14 ... Laser absorption band for position determination;
14a ... Laser light absorption band for determining the position in the X-axis direction;
14b ... laser beam absorption band for determining the position in the Y-axis direction;
14c ... Laser beam absorption band for determining the position in the Z-axis direction;
16 ... Laser light absorption region for displacement detection;
16a ... Laser beam absorption region for detecting displacement in the X-axis direction;
16b... Laser beam absorption region for Y axis direction deviation detection;
16c ... Laser beam absorption region for detecting Z-axis direction displacement;
21 ... Base board; 23 ... Fine adjustment means; 23a ... 1st height adjustment part;
23b ... second height adjustment unit; 23c ... third height adjustment unit;
23d: fine adjustment base board; 25 ... weight;
31 ... Skin mark; 31a ... Skin mark in the X-axis direction;
31b ... Y-axis direction skin mark; 31c ... Z-axis direction skin mark;
33 ... treatment target affected part; 35 ... laser beam for position determination;
35a ... Laser beam for determining the position in the X-axis direction;
35b ... laser beam for position determination in the Y-axis direction;
35c ... laser beam for determining the position in the Z-axis direction;
37 ... Isocenter; 38 ... Patient head fixation pillow; 41 ... Gantry;
41a ... therapeutic X-ray irradiation unit; 42 ... gantry rotating means;
44: diagnostic X-ray imaging apparatus; 44a: diagnostic X-ray irradiation unit;
44b ... diagnostic X-ray detection unit; 46 ... treatment table; 47 ... treatment table end;
48 ... image collecting means; 53 ... rotation center; 55 ... rotation axis;
57 ... Treatment table rotating plate; 59 ... Treatment table holding frame;
71: Actual isocenter.

Claims (14)

X embedded in a displacement measurement phantom placed on a treatment table in a radiotherapy room with respect to a virtual isocenter determined by a position determining laser beam irradiated from the wall surface in the radiotherapy room The position determining laser beam is characterized in that the displacement measuring phantom is fixed at a position where the linear absorbers coincide with each other, and then the following steps (1) and (2) are performed in an arbitrary order. The displacement of the virtual isocenter position from the actual isocenter position by the therapeutic X-ray irradiated from the gantry of the radiotherapy apparatus and the diagnosis irradiated from the diagnostic X-ray imaging apparatus of the radiotherapy apparatus To measure the displacement of the X-ray from the center position:
Process (1)
From the irradiation image information obtained by irradiating the X-ray absorber to the X-ray absorber from the gantry, the actual isocenter position by the therapeutic X-ray and the X-ray absorber arranged at the virtual isocenter A step of measuring a displacement from the position of the step, and a step (2)
From the irradiation image information obtained by irradiating the X-ray absorber to the X-ray absorber from the diagnostic X-ray imaging apparatus, the X-ray absorption arranged at the center position of the diagnostic X-ray and the virtual isocenter The process of measuring the displacement from the body position.   The laser beam for position determination is composed of a laser beam for position determination in the X-axis direction, a laser beam for position determination in the Y-axis direction, and a laser beam for position determination in the Z-axis direction. The measurement method according to claim 1, wherein the laser beam irradiation means for position determination provided on the ceiling and the side wall surface of the room irradiates a single plane perpendicular to each other.   The irradiation image information obtained by irradiating therapeutic X-rays from the gantry to the X-ray absorber is acquired by an image collecting unit provided on a passage extending from the gantry through the X-ray absorber. Or the measuring method of 2.   Irradiation image information obtained by irradiating diagnostic X-rays to the X-ray absorber from the diagnostic X-ray imaging apparatus passes through the X-ray absorber from the diagnostic X-ray irradiation unit of the diagnostic X-ray imaging apparatus The measurement method according to any one of claims 1 to 3, which is acquired by a diagnostic X-ray detection unit provided on a path extending in a straight line.   The displacement obtained by the step (1) and the step (2) according to claim 1, wherein one of the virtual isocenter, the actual isocenter, and the center position of the diagnostic X-ray is selected as an adjustment reference point. Using the measured values, move the two points other than the selected adjustment reference point to coincide with the adjustment reference point, and determine the virtual isocenter, the actual isocenter, and the center position of the diagnostic X-ray. Adjustment method to match.   One of the virtual isocenter, the actual isocenter, or the center position of the diagnostic X-ray is selected as an adjustment reference point, and one of the two points other than the selected adjustment reference point is the first. Using the measured value of displacement obtained by carrying out either step (1) or step (2) according to claim 1, using the moving point and the other point as the second moving point. The displacement measurement value obtained by moving the first movement point so as to coincide with the adjustment reference point, and subsequently performing the other step of the step (1) or the step (2) according to claim 1. Is used to move the second movement point so as to coincide with the adjustment reference point, so that the virtual isocenter, the actual isocenter, and the center position of the diagnostic X-ray coincide with each other.   The virtual isocenter is moved by adjusting the laser beam irradiation means for position determination provided on the wall surface in the radiotherapy room, and the actual isocenter is moved by adjusting the radiotherapy device. The adjustment method according to claim 5 or 6, wherein the movement of the center position is performed by adjusting a diagnostic X-ray imaging apparatus provided in the radiation therapy apparatus.   The adjustment method according to claim 5 or 7, wherein an actual isocenter is selected as an adjustment reference point.   The adjustment method according to claim 6 or 7, wherein an actual isocenter is selected as an adjustment reference point, a virtual isocenter is selected as a first movement point, and a center position of a diagnostic X-ray is selected as a second movement point.   X embedded in a displacement measurement phantom placed on a treatment table in a radiotherapy room with respect to a virtual isocenter determined by a position determining laser beam irradiated from the wall surface in the radiotherapy room The displacement measurement phantom is fixed at a position where the linear absorbers coincide with each other, and the gantry of the radiotherapy apparatus is positioned at the topmost position when the gantry rotating means is rotated about the isocenter as the rotation center. The X-rays for treatment are irradiated from the gantry located at the top in the vertical direction toward the floor, and the irradiation image information after the X-ray absorber is irradiated, and the treatment table rotation A method of measuring the displacement of the panel rotation axis.   Using the measurement result of the displacement obtained in the measurement method according to claim 10, the treatment for irradiation from the gantry positioned at the top of the top when the isocenter is rotated about the rotation center by the gantry rotation means A method of adjusting the displacement between the locus drawn by the X-ray and the rotation axis of the treatment table rotating disk.   The measurement result of the displacement obtained in the measurement method according to any one of claims 1 to 4 and 10 is used to move the treatment table of the radiotherapy device, thereby being fixed on the treatment table. An adjustment method in which a treatment target diseased part of a patient is matched with an actual isocenter position by therapeutic X-rays. Using the virtual isocenter by the laser beam for determining the position of the radiotherapy room and the diagnostic X-ray imaging apparatus of the radiotherapy apparatus, the actual isocenter by the therapeutic X-ray irradiated from the gantry of the radiotherapy apparatus A control system that performs movement control of a treatment table for matching a position and a treatment target affected part of a patient placed on a treatment table in a radiotherapy room,
Displacement of the virtual isocenter position from the actual isocenter position by therapeutic X-rays irradiated from the gantry of the radiotherapy apparatus and irradiation from the diagnostic X-ray imaging apparatus of the radiotherapy apparatus The said control system characterized by introduce | transducing the measurement result of the displacement obtained in the measuring method as described in any one of Claims 1-4 regarding the displacement with respect to the center position of a diagnostic X-ray. The actual isocenter position by therapeutic X-rays irradiated from the gantry of the radiotherapy apparatus, the virtual isocenter position determined by the position determining laser beam irradiated from the wall surface in the radiotherapy room, and diagnostic X A phantom for measuring a displacement from a center position of a diagnostic X-ray irradiated from the diagnostic X-ray imaging apparatus by irradiating the X-ray absorber from the X-ray absorber with a diagnostic X-ray ,
(1) a holding plate having a bottom surface that can be placed on the treatment table of the radiotherapy apparatus, and (2) a position detecting unit provided on the upper surface of the holding plate, the position detecting unit comprising:
(A) a holding rod portion made of an X-ray transparent material;
(B) an X-ray absorber embedded in the holding rod portion;
(C) A linear laser light absorption band that is provided on the surface of the holding rod portion and has a shape that matches the linear image drawn on the surface of the holding rod portion by the laser beam for position determination irradiated from the wall surface in the radiotherapy room And (d) a displacement measuring phantom comprising a displacement detecting laser light absorption region provided on the surface of the holding rod portion so as to intersect the linear laser light absorption band.

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