JP4484789B2 - Spherical fluorescent glass dose measuring element integrated absorbed dose measuring method, spherical fluorescent glass dose measuring element, and integrated absorbed dose measuring apparatus - Google Patents

Description

  The present invention relates to a method for measuring an accumulated absorbed dose of a spherical fluorescent glass dose measuring element, a spherical fluorescent glass dose measuring element, and an apparatus for measuring an accumulated absorbed dose. According to the present invention, radiation can be irradiated from outside the living body with the dosimetry element disposed inside the living body, so that it is possible to measure the accumulated absorbed dose actually irradiated to the target cancer tissue in the living body. become.

  Radiation cancer treatment plays an important role in cancer therapy along with surgery and administration of anticancer drugs. Radiation therapy is not only advantageous in that it is a local treatment that treats only the cancer tissue and its surroundings, as is the case with surgical treatment, but it also eliminates the need for organ removal like surgery and preserves the organ. Excellent in terms. However, in radiotherapy, it is necessary to irradiate the lesion with a large amount of radiation that is incomparable with the amount irradiated to obtain an image in an X-ray examination. Therefore, in order to reduce or prevent side effects, cancer tissue However, it is required to suppress the damage by irradiating an optimal dose of radiation to the surrounding normal tissue while reducing the dose of radiation to the surrounding normal tissue as much as possible.

For example, Intensity Modulated Radio Therapy (IMRT), which is one of the radiation therapies, is adapted to the position and shape of the cancer tissue of the patient being treated, and the shape of the radiation field and the radiation The incident direction is adjusted to irradiate the patient's cancer tissue with radiation, and the accumulated absorbed dose due to the radiation irradiation is optimized. Therefore, radiation treatment can be effectively performed by accurately concentrating the radiation on the affected area. When performing such IMRT, it is necessary to create a treatment plan first and set irradiation conditions that can accurately perform radiation irradiation with a predetermined absorbed dose distribution on the affected part. It is necessary to experimentally verify the validity of a proper treatment plan.
In this case, since it has been practically impossible to insert a dosimeter into the human body and perform experimental dosimetry in the past, a human body model composed of human body equivalent materials, that is, a phantom [ For example, a dosimeter was inserted into Patent Documents 1 and 2] to conduct experimental dosimetry.

However, it is impossible to create a phantom under the same conditions as the human body, and it is also impossible to create a phantom unique to each specific patient. Therefore, the measurement value obtained by using the phantom is only an estimation value in the first place, and the integrated absorbed dose specific to each specific patient cannot be measured or estimated.
In addition, even when radiation therapy was performed according to the treatment plan, whether the cumulative absorbed dose of radiation actually irradiated to the target cancer tissue and surrounding tissues in the living body was the cumulative absorbed dose according to the treatment plan. Conventionally, there has been no means for confirming this. Therefore, for example, even if an over-irradiation accident due to human error has occurred, it has often been extremely difficult to confirm it definitely.

JP-A-11-64530 JP 2003-47666 A

  Accordingly, an object of the present invention is to provide a means capable of measuring the cumulative absorbed dose of radiation actually irradiated to a tissue in a living body (for example, a target cancer tissue or a surrounding tissue).

The above problems are solved by the present invention.
(1) irradiating the spherical fluorescent glass dosimetry element with radiation (hereinafter sometimes referred to as a radiation irradiation step);
(2) The hemispherical depression corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dosimetry element is provided on one surface and the other surface is a flat surface. Place the spherical fluorescent glass dosimetry element after irradiation (hereinafter sometimes referred to as a placing step),
(3) A plate-like cover having a hemispherical depression corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dosimetry element on one surface and the other surface being a flat surface, and the spherical fluorescence after irradiation. The spherical fluorescent glass dosimetry element is sandwiched between the hemispherical depression of the flat plate-like support board and the hemispherical depression of the flat plate-like cover, stacked on the support board on which the glass dosimetry element is placed and supported. To form a stacked set (hereinafter, sometimes referred to as a stacking step),
(4) Irradiating excitation light to the stacked set and measuring emitted fluorescence (hereinafter sometimes referred to as fluorescence measurement step)
This can be solved by a method for measuring the accumulated absorbed dose of the spherical fluorescent glass dosimetry element.

In a preferred embodiment of the method of the present invention, the radiation irradiating step is performed by irradiating a spherical fluorescent glass dosimetry element disposed in a living body.
In another preferred embodiment of the method of the present invention, the flat platen and the flat plate cover are each made of glass.

  The present invention also relates to a spherical fluorescent glass dose measuring element, and the preferable spherical fluorescent glass dose measuring element of the present invention is used in the method for measuring the accumulated absorbed dose.

Furthermore, the present invention provides
(1) a spherical fluorescent glass dosimetry element;
(2) a plate-like support plate having a hemispherical depression corresponding to the shape of the hemispherical part of the spherical fluorescent glass dosimetry element on one surface, and the other surface being a flat surface;
(3) The spherical fluorescent glass dose comprising a flat cover having a hemispherical depression corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dosimetry element on one surface and the other surface being a flat surface. It also relates to a device for measuring the accumulated absorbed dose of the measuring element.
In a preferred aspect of the apparatus for measuring accumulated absorbed dose according to the present invention, the flat support plate and the flat cover have the same shape.

  Since conventional fluorescent glass dosimetry elements are made of glass and are rod-shaped, it is extremely difficult to insert them into a living body without breaking them, and there is a risk of damaging living tissue when broken in vivo. Therefore, it was practically impossible to insert it into the living body. On the other hand, since the spherical fluorescent glass dosimetry element according to the present invention is spherical even if it is made of glass, for example, it can be easily inserted into a living body with a catheter, and there is a risk of breakage at that time. There is almost no sex. Accordingly, the spherical fluorescent glass dosimetry element according to the present invention is attached to the target tissue in the living body and its surrounding tissue, and in a state where it is placed, treatment is performed by irradiating radiation from outside the living body. The accumulated absorbed dose actually irradiated to the surrounding tissue can be directly measured.

  When the fluorescent glass dosimetry element that directly records the accumulated absorbed dose in the living body in this way is sandwiched between the flat support plate and the flat cover as will be described later with reference to the accompanying drawings, an overall flat laminated set Therefore, the fluorescence can be easily measured using the conventional fluorescence measuring apparatus for this flat laminated set.

  Further, since the spherical fluorescent glass dosimetry element according to the present invention is spherical, there is no direction dependency regarding radiation attenuation and the like. Therefore, it is not necessary to pay attention to the radiation irradiation direction when attaching to the target tissue to be irradiated and its surrounding tissues. Furthermore, unlike the X-ray silver salt film used in the conventional method, the spherical fluorescent glass dosimetry element according to the present invention is extremely easy to sterilize by heating, and in this respect, it is also suitable for insertion and placement in a living body. ing.

As described above, the measurement method of the present invention comprises (1) a radiation irradiation step,
(2) Placement process,
(3) includes a lamination step, and (4) a fluorescence measurement step. In the radiation irradiation step (1), a spherical fluorescent glass dosimetry element is used, in the previous step (2), a flat plate support plate is used, and in the lamination step (3), a flat plate cover is used. First, the structure of the spherical fluorescent glass dosimetry device, the flat plate support plate, and the flat plate cover and the method of using them will be described with reference to specific embodiments shown in FIGS.

  FIG. 1 is a schematic perspective view of the flat plate support board 1, FIG. 2 is a schematic perspective view of the flat cover 2, and FIG. 3 shows the spherical fluorescent glass dose measuring element 3 in the flat plate support board 1. FIG. 4 is a schematic cross-sectional view of the stacked set 4 obtained by the process of FIG. 3.

  As shown in FIG. 1, the flat support plate 1 has a flat portion 12 and a hemispherical depression 13 on one mounting surface 11, and is opposite to the mounting surface 11 as shown in FIG. 3. On the side, it has a flat surface 14. Further, as shown in FIG. 2, the flat cover 2 also has a flat portion 22 and a hemispherical depression 23 on one cover surface 21, and as shown in FIG. 3, on the opposite side to the cover surface 21, It has a flat surface 24.

  The spherical fluorescent glass dose measuring element 3 irradiated with radiation in the radiation irradiation step (1) is placed on the flat support plate 1 as shown by an arrow A in FIG. The hemispherical depression 13 in the working surface 11 is charged. In this state, the lower hemispherical portion of the spherical fluorescent glass dose measuring element 3 is stored in the hemispherical recess 13, and the upper hemispherical portion protrudes from the flat portion 12 of the mounting surface 11 and is exposed.

  Subsequently, in the laminating step (3), the spherical fluorescent glass dose measuring element 3 is placed on the mounting surface 11 of the plate-like support plate 1 on which the spherical fluorescent glass dose measuring element 3 is mounted and is shown by an arrow B in FIG. As shown in FIG. At this time, the upper hemispherical portion of the spherical fluorescent glass dose measuring element 3 is covered by the hemispherical depression 23 of the cover surface 21 of the flat cover 2 and the flat portion 22 of the cover surface 21 of the flat cover 2. And the flat portion 12 of the mounting surface 11 of the flat support plate 1 are overlapped with each other. In this way, as shown in FIG. 4, the flat support plate 1 and the flat cover 2 are completely overlapped with each other at the flat portions 12 and 22, and the spherical fluorescent glass dosimeter 3 is a hemispherical shape of both. It is possible to form the stacked set 4 in a state completely wrapped by the depressions 13 and 23.

  In the present specification, the vertical positional relationship (for example, “upward” or “downward”) related to the flat support plate, the flat cover, and the like is the placement step (2) in the measurement method of the present invention and Only the vertical relationship (the direction of gravity) when performing the lamination step (3) is shown, and other states [for example, the state before the placement step (2) or the fluorescence measurement step (4) It is not intended to limit the positional relationship in the state.

  Since the laminated set 4 formed in the laminating step (3) is a flat plate having flat surfaces 14 and 24 on both side surfaces, it is irradiated with excitation light by a conventionally known excitation light irradiation device, and emitted by the excitation light irradiation. Fluorescence can be measured. If necessary, the laminated set 4 is fixed using fixing through holes 15 and 25 provided in the flat support plate 1 and the flat cover 2 and appropriate fixing means (not shown), for example, bolts and nuts. can do. It is also possible to fix with an appropriate binder without providing a fixing through-hole.

  The plate-like support plate 1 and the plate-like cover 2 have the same number of hemispherical depressions 13 and 23 having the same shape on the one surface 12 and 22 respectively, and the overall shape also coincides. It is preferable. In this case, first, the member used when placing and carrying the spherical fluorescent glass dosimetry element is a flat plate support plate, and subsequently, the member used for covering from above is a flat plate cover, Different members are not used.

  The flat support plate and the flat cover can be made of different materials, but are preferably made of the same material (for example, plastic material or glass, preferably glass). Furthermore, it can also consist of the same material (for example, silver activated phosphate glass) as a spherical fluorescent glass dosimeter.

  The number of hemispherical depressions provided on the flat support plate or the flat cover is not limited to two as shown in FIGS. 1 and 2, and may be one or three or more. Further, the shape of the mounting surface of the flat plate support plate and the cover surface of the flat plate cover is not limited to a square shape as shown in FIGS. 1 and 2, for example, a rectangular shape, a polygonal shape, Or it can be circular. Further, when two or more hemispherical depressions are provided, the dimensions thereof do not have to be the same, and a spherical fluorescent glass dosimetry element having a plurality of different particle sizes can be sandwiched and supported at the same time. .

  In the measurement method of the present invention, the spherical fluorescent glass dosimetry element used as a dosimeter is made of, for example, silver activated phosphate glass. Silver activated phosphate glass has been widely used as a glass dosimeter in the form of a rod in the past, but the method of using it in a spherical form has not been known at all. In addition, it is extremely dangerous to insert the fluorescent glass dosimetry element into the living body in the form of a rod, so it has not been performed at all in the past, and it is inserted into the living body instead of the spherical form. Conventionally, no method of irradiating radiation from outside the living body in that state has been used.

The present inventor, for example, as shown in FIGS.
(1) a spherical fluorescent glass dose measuring element 3;
(2) the flat support plate 1 having a hemispherical depression 13 corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dose measuring element 3 on one surface 11 and the other surface 14 being a flat surface;
(3) including a flat cover 2 having a hemispherical depression 23 corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dose measuring element 3 on one surface 21 and the other surface 24 being a flat surface. By developing a device for measuring the accumulated absorbed dose of the spherical fluorescent glass dosimetry element, it has become possible to practically use the spherical form of the fluorescent glass dosimetry element. That is, a laminated set can be easily formed from a spherical fluorescent glass dose measuring element, a flat support plate, and a flat cover, and the use of a conventionally known excitation light irradiation device and fluorescence measuring device can be achieved by this laminated set. It becomes easy.

  In addition, the integrated absorbed dose measuring method using silver activated phosphate glass is based on the following principle. That is, when a silver activated phosphate glass is irradiated with radiation, free electrons and holes are generated, and these are captured by silver atoms to generate fluorescent centers. When the fluorescence center thus generated is irradiated with excitation light, light is emitted. This phenomenon is called radio photoluminescence (RPL). Since the fluorescence intensity emitted in this way is proportional to the radiation dose (ie, the accumulated absorbed dose), the accumulated absorbed dose can be accurately quantified by measuring the fluorescence intensity. Has been used. As the excitation light, ultraviolet rays having a wavelength of 300 to 400 nm can be used. For example, when excited with about 320 nm ultraviolet light, orange fluorescence is emitted.

  The fluorescence intensity can be measured by any measuring means from the fluorescence emitted by irradiating the excitation light. As the measuring means, for example, a CCD camera or a photomultiplier can be used. When a high-sensitivity CCD camera is used, the fluorescence intensity can be changed into an electric signal, and the electric signal can be processed by a computer. The RPL center is stored very stably for a long time even if it is left as it is, and even if it emits fluorescence by irradiating excitation light, it does not disappear by the treatment. Furthermore, the accumulated dose can also be measured quantitatively and has no energy dependency (that is, the sensitivity does not change depending on the energy of irradiation radiation as in the case of X-ray silver salt photographic film). Also excellent in terms. In addition, by heating (annealing) at a high temperature (for example, about 400 ° C. or more) for about 3 hours, the fluorescence center disappears, and radiation dose can be newly accumulated from the beginning.

  As described above, the spherical fluorescent glass dosimetry element used in the measurement method of the present invention extinguishes the fluorescence center by heating (annealing) at a high temperature (for example, about 400 ° C.), and newly accumulates the radiation dose from the beginning. Do. That is, since the spherical fluorescent glass dosimetry element can be heated to, for example, about 400 ° C., itself can be sterilized very easily. This point is also suitable for in vivo irradiation.

  In the said radiation irradiation process (1) of the measuring method of this invention, the said spherical fluorescent glass dosimetry element can be arrange | positioned in a biological body, and a radiation can be irradiated. When placed and placed in a living body, for example, the spherical fluorescent glass dosimetry element is inserted into the tip of the catheter, guided to the target organ in the living body, and the spherical fluorescent glass dosimetry element is released from the catheter. Then, it is affixed to the surface or inside of the target organ, the catheter is extracted, and then irradiation is performed. After the irradiation is completed, the spherical fluorescent glass dosimetry element can be collected again using the catheter. it can. In addition, irradiation is performed with the spherical fluorescent glass dosimetry element placed at the tip of the catheter, and after completion of radiation irradiation, the catheter is extracted, and the spherical fluorescent glass dosimetry element after completion of radiation irradiation is collected. You can also. When a plurality of the spherical fluorescent glass dosimetry elements are inserted at the distal end of the catheter, it is preferable to interpose an appropriate spacer (for example, an acrylic resin spacer) between the individual dosimetry elements.

  In the measuring method of the present invention, the silver activated phosphate glass is formed into a spherical body having an arbitrary particle size. The spherical fluorescent glass dosimetry element does not have to be a perfect sphere (a sphere having an arbitrary cross section of a perfect circle), and can be an ellipsoid that is not easily damaged during insertion and placement in a living body. Since there is no dependency on the irradiation direction, it is preferable to use a perfect sphere. The particle diameter of the spherical fluorescent glass dosimetry element can be appropriately determined according to the part in the living body to be inserted and arranged. In particular, it is preferable that the dimensions be such that the spherical fluorescent glass dosimetry element can be recovered by using a catheter and then affixing to the surface or inside of the target organ in the living body and using the catheter again.

  For example, when the spherical fluorescent glass dosimetry element is inserted and arranged by a catheter into a stomach cancer lesion of a stomach cancer patient, the particle diameter of the dosimetry element is preferably about 1 mm to 3 mm. In the case of a patient, the particle size is preferably about 1 mm to 3 mm.

  In addition, the spherical fluorescent glass dosimetry element can be used without using a catheter for irradiation of a tongue cancer patient or pancreatic cancer patient. For example, in the case of a tongue cancer patient, a spherical fluorescent glass dosimetry element having a relatively large particle size (for example, about 2 mm to 4 mm) is prepared and placed on the surface of the tongue cancer lesion using tweezers. Irradiation can also be carried out in a state of being fixed in the mouth. Furthermore, for intraoperative irradiation of pancreatic cancer, a spherical fluorescent glass dosimetry element having a relatively large particle size (for example, about 2 mm to 4 mm) is prepared and placed at or near the pancreatic lesion during laparotomy. Irradiation can be performed. X-ray silver salt film has been used for conventional intraoperative irradiation of pancreatic cancer. However, since the X-ray silver salt film itself cannot be sterilized, it must be wrapped in a sterilized plastic cover. It was. On the other hand, in the measuring method of the present invention, the spherical fluorescent glass dose measuring element can be heat sterilized, which is also convenient in this respect.

  The integrated absorbed dose measurement method of the present invention can irradiate radiation from outside the living body with the spherical fluorescent glass dosimetry element disposed inside the living body, and thus the integrated absorption actually irradiated to the target cancer tissue in the living body. The dose can be directly measured, and an accurate integrated absorbed dose can be obtained.

It is a typical perspective view of a flat support board. It is a typical perspective view of a flat cover. It is sectional drawing which illustrates typically the process of mounting a spherical fluorescent glass dosimeter on a flat support board, and overlapping a flat cover from it. It is typical sectional drawing of the lamination | stacking set obtained by the process of FIG.

Explanation of symbols

1 ... Flat plate support board;
2 ... Flat cover;
3 ... Spherical fluorescent glass dosimetry element;
4 ... Laminated set;
11 ... mounting surface;
12, 22 ... flat part;
13, 23 ... hemispherical depression;
14, 24 ... flat surface;
15, 25 ... fixing through hole;
21 ... Cover surface.

Claims (6)

(1) A radiation irradiation step of irradiating the spherical fluorescent glass dosimetry element with radiation,
(2) The hemispherical depression corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dosimetry element is provided on one surface and the other surface is a flat surface. A placing step of placing the spherical fluorescent glass dose measuring element after irradiation;
(3) A plate-like cover having a hemispherical depression corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dosimetry element on one surface and the other surface being a flat surface, and the spherical fluorescence after irradiation. The spherical fluorescent glass dosimetry element is sandwiched between the hemispherical depression of the flat plate support board and the hemispherical depression of the flat cover so as to be stacked from above the support board on which the glass dosimetry element is placed and supported. Accordingly, the lamination process to form a laminated set, and (4) the irradiation with excitation light in the lamination set, the fluorescence measurement step of measuring the fluorescence emitted
Characterized in that it comprises a method of measuring the cumulative absorbed dose of the spherical fluorescent glass dosimetry device.   The measurement method according to claim 1, wherein the radiation irradiation step is performed by irradiating a spherical fluorescent glass dosimetry element disposed in a living body with radiation.   The measuring method according to claim 1 or 2, wherein the flat support plate and the flat cover are each made of glass.   The spherical fluorescent glass dosimetry element used for the measuring method as described in any one of Claims 1-3. (1) a spherical fluorescent glass dosimetry element;
(2) a plate-like support plate having a hemispherical depression corresponding to the shape of the hemispherical part of the spherical fluorescent glass dosimetry element on one surface, and the other surface being a flat surface;
(3) a flat cover having a hemispherical depression corresponding to the shape of the hemispherical portion of the spherical fluorescent glass dosimetry element on one surface and the other surface being a flat surface;
A device for measuring an accumulated absorbed dose of the spherical fluorescent glass dose measuring element.   6. The integrated absorbed dose measurement apparatus according to claim 5, wherein the flat support plate and the flat cover have the same shape.

Images