KR20070118394A - Phantom for radiation dosimetry - Google Patents

Abstract

A phantom for radiation dosimetry is provided to predict radiation dosimetry of all depth and parts of a body by including a plurality of mimetic materials having tissue density corresponding to tissue density of a specific part of the body. A phantom for radiation dosimetry includes a wedge plate(25) and a radiation dosimetry part. The phantom is placed at a lower part of a radiation radiating part, receives radiation from the radiation radiating part and measures an amount of radiation. The wedge plate passes the radiation from the radiation radiating part and forms a slope by sloping an upper surface of the wedge plate. The radiation dosimetry part is placed to the lower part of the wedge plate and measures the amount of the radiation passed through the wedge plate.

Description

Phantom for radiation dosimetry

1 is a view showing for explaining the use example of the radiation dose measurement phantom according to an embodiment of the present invention.

2 is an exploded perspective view of a radiation dose measurement phantom according to an embodiment of the present invention.

Figure 3 is a perspective view showing a separate ion chamber mounting plate that can be added to the phantom shown in FIG.

4 to 6 are views schematically shown to explain various uses of the radiation dose measurement phantom according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

11: Linear accelerator 13: Body

15: rotating gantry 17: radiation emitting unit

19: treatment table 21: phantom

23: mimic 25: wedge plate

25a: Through hole 25b: Sloped surface

27: Base plate 27a: Female threaded ball

29: mimetic accommodation plate 29a: through hole

29b, 29c: space 31: flat plate

31a: Through hole 33: Thermal fluorescent dose meter mounting plate

33a: through hole 33b: heat fluorescent dose meter accommodation hole

35: fixed rod 35a: male thread

36: Nut 39: ion chamber mounting plate

39a: through hole 39b: ion chamber fitting

51: X-ray film 53: thermal fluorescence dosimeter

55: ion chamber

The present invention relates to a radiation dose measuring phantom for measuring the dose of radiation generated in various radiation output devices.

Among the radiations used for medical purposes, therapeutic radiation is applied to cancer patients' tumors so that cancer cells can no longer reproduce and are used to kill cancer cells at the end of their life or to relieve pain.

Radiation therapy using therapeutic radiation can be used, for example, to prevent recurrence if the cancer cells are more likely to remain after surgery, or to fail surgery, or to be more effective than surgery, or surgery and radiation therapy. If you want to improve the quality of life of the patient in parallel, or in combination with chemotherapy to maximize the anti-cancer effect.

The radiation therapy is performed by expensive medical equipment called linear accelerators. The linear accelerator can output high dose rate X-rays and electron beams, as well as finely control the output energy, and is currently used as a standard equipment for radiation therapy.

However, when performing radiation treatment with the linear accelerator, the most important thing is to allow the linear accelerator to output radiation of appropriate energy. It is very important to ensure that the linear accelerator outputs the radiation with the optimal energy because the maximum therapeutic effect can be achieved only by irradiating the radiation with the optimal energy corresponding to the condition, size, or depth of the tumor.

Therefore, before using the linear accelerator, it is necessary to check the operation precision such as whether the linear accelerator operates properly, in particular, the radiation dose is properly adjusted to output the required energy radiation. This is called Quality Assurance and is actually performed in a hospital periodically or non-periodically.

Various kinds of radiation dose measuring apparatuses are used for the quality control. The radiation dose measuring apparatus is located under the radiation emitter to irradiate radiation and generate a signal corresponding to the magnitude of the irradiated energy to inform the outside.

Without the above-mentioned measuring device, it is impossible to optimize the size of the output radiation energy according to the characteristics of the patient's tumor. Therefore, it is impossible to prescribe optimal radiation, and thus the treatment effect is very low. This could lead to medical deaths.

On the other hand, conventional radiation dose measuring devices are mostly dependent on imports, and moreover, their price reaches tens of thousands to hundreds of thousands of dollars, so it is practically impossible to hold and operate such measuring devices financially in small and medium-sized hospitals. In addition, the conventional radiation dose measuring device has a problem that it takes a long time to set the device. Therefore, there is a problem that the quality control itself can be neglected because it is cumbersome to manage the radiation treatment device every busy morning.

The present invention has been made to solve the above problems, the structure is simple, inexpensive, and has a large number of mimetics having a tissue density corresponding to the tissue density of a predetermined part in the body, the radiation dose at all depths and parts of the body It is an object to provide a phantom for radiation dose measurement that can accurately predict the, and in particular having a wedge plate having an inclined surface, it is possible to grasp the degree of radiation reaching the target with a different depth.

In order to achieve the above object, the present invention is to receive the radiation irradiated from the radiation emitting portion in a state located vertically below the radiation emitting portion and to measure the dose, the radiation irradiated from the radiation emitting portion downward A wedge plate passing through the inclined surface thereof to form an inclined surface; Located below the wedge plate and characterized in that it comprises a radiation dose measuring unit for measuring the dose of radiation passing through the wedge plate.

In addition, the radiation dose measuring unit; An acrylic plate having a predetermined thickness is characterized by including a dosimeter mounting plate having one or more accommodation holes therein for accommodating the thermofluorescence dosimeter, and a thermofluorescence dosimeter inserted into the accommodation holes.

In addition, the receiving hole is characterized in that a plurality of horizontally extending side by side and each end is open to the outside of the dosimeter mounting plate.

In addition, the radiation dose measuring unit; An acrylic plate having a predetermined thickness is characterized in that it comprises an ion chamber mounting plate having an installation tool for inserting and installing a tubular ion chamber therein, and an ion chamber mounted to the installation tool.

In addition, between the wedge plate and the radiation dose measuring unit, a mimetic accommodation plate for passing the radiation irradiated from the radiation emitting portion, and accommodates a mimetic body having a tissue density corresponding to the tissue density of a predetermined portion in the body further Characterized in that it is provided.

In addition, the mimetic accommodation plate; Acrylic member having a predetermined thickness, characterized in that it has at least one space that can accommodate the mimetic body therein.

In addition, the space portion is characterized in that it extends horizontally and both ends open to the outside of the replica receiving plate.

In addition, the mimetics are; It is made of Teflon and is characterized in that it comprises one or more teflon plates or cork having a certain thickness and one or more cork plates having a certain thickness.

In addition, the upper portion of the wedge plate is further provided with another wedge plate having the same shape as the wedge plate is laminated so that the inclined surface is in close contact with the wedge plate, the radiation dose irradiated from the outside between the wedge plate in close contact with each other It is characterized in that the x-ray film is inserted for measuring.

Hereinafter, one embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view illustrating an example of using a phantom for radiation dose measurement according to an embodiment of the present invention. In this embodiment, the linear accelerator 11 is used as a radiation emitting device.

Referring to FIG. 1, it can be seen that the phantom 21 according to the present exemplary embodiment is positioned below the vertical portion of the radiation emitting unit 17 in a state where it is placed on the treatment table 19. The treatment table 19 constitutes a set with the linear accelerator 11 and is a bed which the patient to treat is exposed on.

In addition, the linear accelerator 11 includes a main body 13 and a rotating gantry 15 rotatably installed on the main body 13. In the main body 13, a high voltage generator, a microwave generator, and the like are installed, and inside the rotary gantry 15, devices such as an accelerator tube, a magnetic field generator, and a radiation emitter 17 for accelerating electrons are provided. It is provided. The radiation output from the radiation emitter 17 is irradiated to the tumor of the patient lying on the treatment table 19.

On the other hand, the phantom 21 according to the present embodiment, to receive the radiation irradiated downward from the radiation emitting portion 17 in the state set in the vertical lower portion of the radiation emitting portion 17 to be able to grasp the dose of the irradiated radiation do.

The phantom 21 may include one or more base plates 27, a matrix receiving plate 29 having various kinds of replicas 23 embedded therein, a plurality of flat plates 31, and wedges. A plate 25, a thermofluorescence dosimeter mounting plate (hereinafter referred to as TLD mounting plate) (33 in FIG. 2), an ion chamber mounting plate (39 in FIG. 3), and the like are combined. Combination examples of the various components described above may vary as the case may be, for example, may have a laminate structure illustrated in FIGS. 4 to 6.

Reference numeral 51 is an x-ray film. The X-ray film 51 represents the energy level of the radiation reaching the surface as a target of the radiation passing through the wedge plate 25, the flat plate 31, and the mimetic accommodation plate 29.

As a result, the X-ray film 51 is a radiation dose measuring unit for measuring the dose (at the corresponding depth) of the radiation irradiated from the radiation emitting unit 17. In addition to the X-ray film 51, the radiation dose measuring unit includes a TLD mounting plate 33 and a thermoluminescent dosimeter (hereinafter referred to as TLD) (53 in FIG. 2) and an ion chamber mounting plate (in FIG. 3). 39) and an ion chamber (55 in FIG. 4C) applied thereto.

The said radiation dose measuring part has the purpose of measuring the dose of radiation in the depth in which the radiation dose measuring part is located. The depth at which the radiation dose measuring unit is located depends on the combination example described above, and also what kind of mimetic body 23 is located on the upper portion of the radiation dose measuring unit or not, and the like depends on the case.

Figure 2 is an exploded perspective view showing a combination example of the radiation dose measurement phantom according to an embodiment of the present invention.

As shown in the drawing, the radiation dose measurement phantom 21 according to the combination example includes a base plate 27 having a shape of a square plate having a predetermined thickness, and a TLD mounting plate stacked on the base plate 27 ( 33), a replica receiving plate 29, a flat plate 31, a wedge plate 25, which are sequentially stacked on the TLD mounting plate 33, and a fixed rod 35 for coupling the components to each other. It has a configuration including.

The base plate 27 horizontally supports the TLD mounting plate 33 at a predetermined height from the treatment table 19 while being placed on the treatment table 19 as shown in FIG. The base plate 27 is to adjust the distance of the radiation dose measuring unit relative to the radiation emitting unit 17. For example, the thickness of the base plate 27 may be made thick or the number of base plates 27 may be increased to narrow the separation distance of the radiation dose measuring unit with respect to the radiation emitter 17.

Female screw holes 27a are formed at the four corners of the base plate 27. The female threaded mouth 27a is a groove in which a female thread is formed on an inner circumferential surface thereof, and the male threaded portion 35a of the lower end of the fixed rod 35 is coupled thereto. The fixing rod 35 extends vertically in a state coupled to the female screw thread 27a and tightly fixes each component.

The TLD mounting plate 33 is a rectangular acrylic plate having a certain thickness and has five TLD receiving holes 33b extending horizontally therein. The TLD accommodation holes 33b have a predetermined diameter and are side by side, and both ends thereof are open to the outside. Of course, the number of the TLD accommodation holes 33b may vary depending on the case.

For reference, acrylic has a tissue density corresponding to the density of general tissue in the body.

The TLD 53 is inserted into the TLD accommodation hole 33b. As is well known, TLD is a dosimeter made of a material having thermofluorescent properties, and may be manufactured in the form of a chip or in powder form. When in powder form it is sealed in a cylindrical capsule.

In this embodiment, a capsule TLD 53 is used. That is, the capsule-type TLD 53 is inserted into the TLD accommodation hole 33b, and then pushed to the center part to be in position. In particular, a plurality of TLDs 53 may be inserted into one TLD receiving hole 33b, or may be applied only to the selected TLD receiving hole 33b. The TLD 53 receives the radiation irradiated from the top in the state of being located in the TLD receiving hole 33b, and can be quantitatively assessed the radiation dose collected by an operator later and exposed through a TLD reader (not shown). do.

Through holes 33a are formed at four corners of the TLD mounting plate 33. The through hole 33a is a hole through which the fixed rod 35 passes.

In particular, although the TLD mounting plate 33 is illustrated in FIG. 2, the ion chamber mounting plate 39 (the state in which the ion chamber is inserted) and the X-ray film (FIG. 1) shown in FIG. 3 are replaced with the TLD mounting plate 33. 51) may optionally be used. That is, the TLD mounting plate 33, the ion chamber mounting plate 39, or the X-ray film is selectively used.

The upper part of the TLD mounting plate 33 is provided with a mimetic accommodation plate 29. The mimetic accommodating plate 29 is a hexahedral acryl block having a vertical through hole 29a at four corners, and includes two spaces 29b and 29c therein. The spaces 29b and 29c extend horizontally in parallel with each other and are rectangular holes with both ends open to the outside. The cross-sectional shape or size of the spaces 29b and 29c may vary depending on the case.

Basically, the spaces 29b and 29c may be empty or filled with the mimetic body 23, depending on the object to be copied in the body. For example, when simulating an empty space such as an oral cavity, the space 29c is left empty. Also, when simulating lungs, cork is known to have a similar tissue density to the lungs, and when simulating bones, a teflon having a similar tissue density to bones is inserted. The replica 23 may be manufactured in the form of a block, or may be manufactured in the form of a thin plate and then laminated as necessary. The mimetic accommodation plate 29 may not be used in some cases.

The flat plate 31 located above the mimetic accommodation plate 29 is a rectangular acrylic plate having various thicknesses. The flat plate 31 serves to control the distance of the target to the radiation emitting unit 17. Therefore, the position or the number of sheets of the flat plate 31 may vary as necessary. For example, it may be located between the base plate 27 and the TLD mounting plate 33, or may be installed between the wedge plate 25 and the mimetic accommodation plate 29 as shown. It goes without saying that the through holes 31a are also provided at four corners of the flat plate 31.

On the other hand, the wedge plate 25 is an acrylic member having a side shape of a right triangle. The wedge plate 25 has a horizontal bottom surface and an inclined surface 25b inclined at a predetermined angle with respect to the bottom surface. The inclination angle of the inclined surface 25b is about 15 to 30 degrees.

Basically, the wedge plate 25 serves to linearly determine the degree of radiation arrival to the target of different depths. For example, when the radiation is irradiated onto the wedge plate 25 in a state where the X-ray film is positioned below the wedge plate 25, the energy of the radiation is linear to the wedge plate 25 (the thickness of the wedge plate is inclined because the wedge plate is inclined). As it passes downward, the radiation of the smaller and smaller energy is reflected on the X-ray film, and thus the radiation attenuation information about the thickness of the acrylic can be obtained. If the radiation passes through the thick portion of the wedge plate 25, the attenuation rate is so great that less radiation passes through the relatively thin portion.

The through hole 25a is formed in the four corners of the wedge plate 25.

The fixed rod 35 is to vertically support the components on the upper portion of the base plate 27 (the combination example of each component can be different), the TLD mounting plate 33 and the replica receiving body Through-holes 33a, 29a, 31a, and 25a of the plate 29, the flat plate 31 and the wedge plate 25 penetrate the male threaded portion 35a at the lower end thereof and the female threaded mouth 27a of the base plate 27. It is fixed to).

Reference numeral 36 is a nut for fastening the components to each other by coupling to the male screw portion 35a of the upper end of the fixing rod 35.

3 is a perspective view separately showing the ion chamber mounting plate 39 that may be added to the phantom shown in FIG.

As shown, the ion chamber mounting plate 39 is a rectangular acrylic plate having a predetermined thickness and has a through hole 39a through which the fixing rod 35 passes at four corners. Moreover, one ion chamber fitting 39b is provided inside.

The ion chamber fitting 39b extends horizontally as a groove into which the ion chamber 55 shown in FIG. 4C or 5C is fitted. The ion chamber 55 is a known radiation dose measuring device that receives radiation from the outside and generates an electrical signal proportional to the radiation dose received.

4 to 6 are views schematically shown to explain various uses of the phantom for radiation dose measurement according to an embodiment of the present invention. For convenience, the fixed rod 35 is not shown.

Referring to FIG. 4A, it can be seen that two flat plates 31 and wedge plates 25 are sequentially stacked on the base plate 27 to form one phantom 21. In particular, an X-ray film 51 is sandwiched between the base plate 27 and the flat plate 31. The position of the X-ray film 51 may be changed as much as required.

The X-ray film 51 receives the radiation irradiated from the top while being in close contact with the base plate 27, and shows the dose of the radiation that has passed through the wedge plate 25 and the two flat plates 31 in sequence. That is, the X-ray film 51 is developed later to display the planar level of the radiation energy at the depth where the film is located.

In FIG. 4B, the TLD mounting plate 33 is provided in place of the X-ray film 51. That is, the phantom 21 shown in FIG. 4B is located on the base plate 27, the TLD mounting plate 33 stacked on the base plate 27, and the upper portion of the TLD mounting plate 33. It consists of a flat plate 31 and a wedge plate 25. The TLD 53 is inserted into the TLD receiving hole 33b of the TLD mounting plate 33, of course.

When radiation is irradiated to the phantom 21 laminated as described above, the radiation passes through the wedge plate 25 and the flat plate 31 in order to reach the TLD 53. The TLD 53 memorizes the radiation dose at the location and informs of the radiation dose that was later retrieved and irradiated through a known reader.

4C is a diagram illustrating a case where the ion chamber 55 is applied as the radiation dose measuring unit.

As shown in FIG. 4C, the ion chamber mounting plate 39 and the wedge plate 25 are stacked on the base plate 27. In addition, the ion chamber 55 is inserted into the ion chamber mounting plate 39.

Therefore, the radiation irradiated from the radiation emitting unit 17 passes through the wedge plate 25 to reach the ion chamber 55. The ion chamber 55 generates an electric signal corresponding to the received radiation dose and transmits it to the outside, and allows the operator to determine the radiation dose passing through the wedge plate 25.

5A to 5C are diagrams showing an example in which the mimetic body 23 is positioned on the radiation dose measuring unit (X-ray film 51, TLD 53, ion chamber 55).

The phantom 21 illustrated in FIG. 5A includes a base plate 27, an X-ray film 51 fitted to an upper portion of the base plate 27, and a replica body stacked on an upper portion of the X-ray film 51. The plate 29 and the flat plate 31 and the wedge plate 25 are sequentially stacked on the mimetic accommodation plate 29.

In particular, a replica 23 is inserted into one space 29b of the replica receiving plate 29. The mimetics mimic the lungs or bones as mentioned above as members made of cork or Teflon. Whether cork or Teflon is used as the mimetics depends on the radiation site of the actual patient to be treated with the linear accelerator.

For example, cork is used as the mimetic body 23 when the patient's lung is to be irradiated, and teflon is used when the radiation is to be irradiated to or under the bone. The thickness of the mimetic 23 corresponds to the depth of the site of interest (eg, tumor) to be irradiated.

Using the mimetic body 23 (instead of the actual patient) as described above, the amount of radiation to be applied to the radiation target site of the actual patient is determined in advance, and it is determined whether the radiation is properly irradiated to determine the linear accelerator. You can verify the accuracy. As such, it is well known in the medical engineering field to check the precision of a radiation generator such as a linear accelerator using a mimetic instead of a real patient.

In any case, referring to FIG. 5A, it can be seen that the radiation irradiated from the radiation emitting unit passes through the wedge plate 25, the flat plate 31, and the mimetic accommodation plate 29 in order to reach the X-ray film 51. have. Particularly, part of the radiation to be irradiated passes through the mimetic body 23 and the space part 29c so that the plane level of the radiation energy passing through the mimetic body 23 and the space part 29c is displayed on the X-ray film 51. do.

The phantom 21 shown in FIG. 5B is a case where the TLD mounting plate 33 is located under the mimetic accommodation plate 29. The TLD 53 applied to the TLD mounting plate 33 receives radiation from the upper part and passes through the mimetic body 23 and the space part 29c, and stores the dose of radiation at the corresponding location. Inform the user through the method.

5C, it can be seen that the ion chamber mounting plate 29 and the ion chamber 55 are installed under the mimetic accommodation plate 29. The ion chamber 55 measures and informs the dose of radiation that has passed through the wedge plate 25, the flat plate 31, the replica 23, and the space 29c.

Meanwhile, the phantom 21 illustrated in FIG. 6 includes a base plate 27, a flat plate 31 stacked on an upper portion of the base plate 27, and a wedge provided on an upper surface of the flat plate 31. The plate 25 and the other wedge plate 25 is stacked on top of the wedge plate 25, the inclined surface thereof is installed to be in close contact with the inclined surface of the lower wedge plate toward the bottom.

In particular, the X-ray film 51 is sandwiched between the two wedge plates (25). Since the X-ray film 51 is in close contact with the inclined surface of the wedge plate 25, the x-ray film 51 is irradiated with the radiation in the inclined angle of the inclined surface. Therefore, the X-ray film 51 is developed later to let you know the three-dimensional energy level of the radiation passing through the wedge plate (25).

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to the said Example, A various deformation | transformation is possible for a person with ordinary knowledge within the scope of the technical idea of this invention.

The radiation dose measurement phantom of the present invention as described above has a large number of mimetics having a simple structure, low cost, and having a tissue density corresponding to the tissue density of a predetermined part of the body at all depths and parts of the body. The radiation dose can be accurately predicted, and in particular with a wedge plate having an inclined surface, it is possible to linearly grasp the degree of radiation reaching the target having a different depth.

Claims (9)

It is to take the radiation irradiated from the radiation emitting portion in the state located vertically below the radiation emitting portion and measure the dose, A wedge plate through which the radiation irradiated from the radiation emitter passes downward, the upper surface of which is inclined to form an inclined surface; Radiation dose measurement phantom, characterized in that it comprises a radiation dose measuring unit for measuring the dose of radiation passing through the wedge plate and located below the wedge plate. The method of claim 1, The radiation dose measuring unit; Radiation dose measurement phantom, comprising: a dosimeter mounting plate having one or more accommodation holes therein for accommodating the thermofluorescence dosimeter as an acrylic plate having a predetermined thickness, and a thermofluorescence dosimeter inserted into the accommodation holes; . The method of claim 2, A plurality of receiving holes are horizontally extended side by side and each end of the radiation dose measurement phantom, characterized in that both ends are open to the outside of the dosimeter mounting plate. The method of claim 1, The radiation dose measuring unit; An ion chamber mounting plate having an installation hole for inserting and installing a tubular ion chamber therein as an acrylic plate having a predetermined thickness, and an ion chamber mounted to the installation hole. The method according to any one of claims 1 to 4, Between the wedge plate and the radiation dose measuring unit, A radiation dose measurement phantom, characterized in that the radiation receiving unit passes through the radiation, the body receiving plate for receiving a mimetic body having a tissue density corresponding to the tissue density of a predetermined portion in the body is provided. The method of claim 5, The mimetic accommodation plate; An acrylic member having a predetermined thickness, wherein the radiation dose measurement phantom, characterized in that it has at least one space portion capable of accommodating the mimetic body therein. The method of claim 6, The space portion, the radiation dose measurement phantom, characterized in that it extends horizontally and both ends open to the outside of the replica receiving plate. The method of claim 6, The mimetics; Radiation dose phantom, characterized in that it comprises one or more teflon plate or cork plate made of Teflon and having a certain thickness and having a certain thickness. The method of claim 1, The upper side of the wedge plate is further provided with another wedge plate having the same shape as the wedge plate, but the inclined surface is laminated so as to closely contact the wedge plate, Radiation dose phantom, characterized in that the x-ray film for measuring the radiation dose from the outside is inserted between the wedge plate in close contact with each other.

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