WO2006104046A1

WO2006104046A1 - Radiation dose measuring element and radiation dose measuring device using electric-insulating polymer material

Info

Publication number: WO2006104046A1
Application number: PCT/JP2006/305986
Authority: WO
Inventors: Mitsuo Shimozuma; Hiroyuki Date; Josuke Nakata; Hidemasa Tomozawa
Original assignee: National University Corporation Hokkaido University; Kyosemi Corporation
Priority date: 2005-03-25
Filing date: 2006-03-24
Publication date: 2006-10-05
Also published as: JPWO2006104046A1

Abstract

A radiation dose measuring element and a radiation dose measuring device that use an electric-insulating polymer material which is excellent in processability, measures the dose of a material kept very close to a body tissue, and can detect a large signal current over a wider voltage (for example, a small under-current at a low voltage of up to 10V). The measuring element comprises a substrate (11) made of a polymer material having an electric-insulating property at room temperature, and at least a pair of electrodes (12, 12) provided on the surface of or inside this electric-insulating polymer substrate (11), wherein, when radiation is applied to the substrate (11), an output current value linear and unique to the dose rate of the radiation is obtained.

Description

Specification

Radiation dosimetry element and radiation dosimeter using electrical insulating polymer material

Technical field

TECHNICAL FIELD [0001] The present invention relates to a radiation dosimetry element and a radiation dosimetry device, and more particularly, to in vivo absorbed dose in radiation therapy, exposure dose due to irradiation of diagnostic X-rays, exposure in a radiation control area, and general environmental radiation. The present invention relates to a radiation dosimetry element and a radiation dosimetry apparatus using an electrically insulating polymer material suitable for measuring exposure doses and the like. Background art

[0002] Conventionally, techniques for measuring the absorbed dose, irradiation dose, radiation intensity, and the like of radiation have been proposed. For example, Japanese Patent Laid-Open No. 9-167594 discloses a radiation detector using a proportional counter (Patent Document 1). This radiation detector has a counter tube filled with gas, and a linear electrode is disposed in the center of the counter tube. Then, electrons and ion pairs ionized by the incident radiation are collected on a linear electrode to which a voltage is applied, and the energy and dose of the radiation are measured based on the norse output from the linear electrode. When a proportional counter tube is used as a biological tissue model, the measurement is performed by enclosing a biological tissue equivalent gas inside the counter tube.

[0003] In addition, Japanese Patent Application Laid-Open No. 2004-20249 proposes a radiation detection apparatus using an ionization chamber (Patent Document 2). This radiation detector is provided with a central electrode in an ionization chamber filled with gas. The intensity of the radiation is measured based on the amount of ions ionized and produced in the gas by the radiation incident on the ionization chamber. When using an ionization chamber as a living body model, insert a finger-type ionization chamber into an insertion hole that leads to a tank filled with water, and measure the radiation dose assuming that it is equivalent to a living tissue. ! / Speak.

[0004] Furthermore, the Radiation Detector described in US Pat. No. 6,278,117 is configured so that a metal electrode is wired on a “polymeric substrate” and covered with this metal electrode. An “active polymeric layer” is formed (Patent Document 3). And Thus, it is said that the radiation dose is measured based on the current change in the “active polymeric layer” when irradiated with radiation.

[0005] In addition, the radiation sensor described in JP-A-5-107360 is composed of "organic polymer substance containing halogen" and "polyarine" (Patent Document 4). The dose is calculated using the fact that the electrical conductivity of this “polyaniline” depends on the dose of radiation.

[0006] In addition, the radiation detection element described in JP-A-2-143188 has a “composition” composed of a “conductive polymer compound” and a “radiation sensitive substance” on a pair of electrodes provided on an insulating substrate. It is configured by applying an object ”(Patent Document 5). Then, the amount of radiation is measured by utilizing the fact that the dopant generated when the radiation sensitive substance is irradiated with radiation is doped into the conductive polymer compound and its conductivity and resistance change. is doing.

[0007] Further, in the radiation detection element described in JP-A-62-299780, the detection layer is composed of a polymer or rubber to which a “conductivity imparting agent” is added (Patent Document 6). Then, the amount of irradiation is detected by utilizing the fact that the resistance value decreases as the amount of radiation irradiation increases.

Patent Document 1: Japanese Patent Application Laid-Open No. 9 167594

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-20249

Patent Document 3: US 6,278,117

Patent Document 4: JP-A-5-107360

Patent Document 5: JP-A-2-143188

Patent Document 6: Japanese Patent Laid-Open No. 62-299780

Disclosure of the invention

Problems to be solved by the invention

However, the conventional radiation measuring apparatus including the inventions described in Patent Document 1 and Patent Document 2 described above has the following problems.

(1) Conventional devices that attempt to measure tissue absorbed dose use tissue-equivalent gas or water assuming a biological tissue model, but because the human body is essentially understood as a mixture of liquid and solid. There is a high possibility that an error from the radiation dose actually absorbed by the human body will occur. This Here, the absorbed dose represents the amount of energy absorbed per unit mass of the substance. Therefore, the amount depends on the type of substance.

(2) Since conventional proportional counters and ionization chambers have almost no degree of freedom in shape, they cannot be formed into curved shapes such as human body parts or organs, spherical shapes, or complex shapes for measurement. There is a possibility that an error with the absorbed dose received by a human body part or organ increases.

(3) In the case of a proportional counter, in order to enclose a volume of tissue-equivalent gas equivalent to the biological tissue to be measured, the counter tube must be considerably large, and the entire apparatus becomes large. .

(4) In the case of an ionization chamber, when calculating the radiation dose, it is necessary to calibrate using a conversion formula based on the Bragg's gray principle that takes into account the physical properties of the gas and build-up caps and other wall materials. And the calculation process is complicated.

(5) For proportional counters and ionization chambers, a special power supply is required, with the applied voltage being as high as 500V to 800V.

[0010] On the other hand, radiation detectors using semiconductor elements are also known. Under high-intensity radiation environments, semiconductor elements are electrically broken or deteriorated, and there is a problem of lack of durability. Not suitable as a dosimetry device.

Further, in Patent Document 3 described above, after an electrode is printed on a “polymeric substrate” by photolithography, an “active polymeric layer” corresponding to the “polymer substrate” of the present application is formed thereon. (Active polymer layer) ". For this reason, as shown in FIG. 2, there is a problem that the manufacturing process is increased with a complicated structure and the cost is increased.

Furthermore, in Patent Document 3, as shown in FIG. 2, the metal electrodes are complicatedly wired at extremely small intervals, so that the output current when not irradiated with radiation (hereinafter referred to as “dark current”). ) Will be larger. For this reason, as shown in FIG. 4, when the applied voltage is in the range of IV or higher, the output current value when irradiated with radiation overlaps with the dark current or is lower than the dark current. Also, as shown in FIG. 5, the resistance ratio (radiation OFFZ radiation ON) is 1.0 or less in the range where the applied voltage is 4V or more. That is, in the range of the applied voltage force S IV or more, the dark current is larger than the signal current that increases when radiation is applied, so the signal current cannot be determined and it is difficult to use as a radiation detector. [0013] Furthermore, the radiation detection elements described in Patent Documents 4 to 6 are intended for conductive polymers, and do not consist solely of polymer materials. That is, Patent Document 4 synthesizes “polyarine” to “organic polymer substance containing halogen”, and Patent Document 5 discloses “composition” on a pair of electrodes provided on an insulating substrate. In Patent Document 6, a “conductivity imparting agent” is added to a polymer or rubber, both of which are directed to a conductive polymer.

[0014] The present invention has been made to solve such problems, and has an object to obtain at least one of the following operational effects. In other words, it is possible to reduce the size, simplify, and reduce the cost by forming solid materials as various polymer materials such as tissue equivalent plastics that do not use gas as a measurement element. Therefore, the absorbed dose can be accurately measured in a state closer to a living tissue, for example, by being attached to a human body part or by forming an organ model by forming it into an organ shape. In addition, the radiation dose can be measured in real time. In addition, by using a polymer material that is electrically insulating at room temperature, a large signal current can be detected in a small dark current and used as a dosimetry element even in a wide voltage range (eg, a low voltage of 10 V or less). An object of the present invention is to provide a radiation dosimetry element and a radiation dosimetry device using an electrically insulating polymer material.

Means for solving the problem

In the Japanese Patent Application No. 2004-151087, the present inventors have already formed a thin film layer made of a semiconductor or an insulator on the surface of a base member made of tissue-equivalent plastic, and paired with this thin film layer. We have invented a dosimetry device equipped with these electrodes and are proposing that it can solve the conventional problems. And this time, the inventors have further researched, and even if the element is composed only of an electrically insulating polymer material without forming the above-described semiconductor or insulator thin film layer, The linearity with the output current was obtained, and the operation as a radiation sensor was confirmed. According to this, it is remarkably excellent in formability and drastically reduces costs, and is highly practical. In addition, since polymer materials are close to low atomic number substances in living tissues, it is easy to estimate absorbed doses in living bodies. There is a merit fall.

[0016] Therefore, the radiation dosimetry element using the electrically insulating polymer material according to the present invention is characterized by a substrate made of a polymer material having electrical insulation properties at room temperature, and the electrically insulating polymer. It has at least a pair of electrodes provided on the surface or inside of the substrate.

[0017] Further, in the present invention, the electrically insulating polymer substrate has an output current value linearly unique with respect to the radiation dose by irradiation of radiation.

[0018] Here, the mechanism of the present invention will be described. The phenomenon in which the photovoltaic effect of an insulator or semiconductor irradiated with light when the insulator or semiconductor is irradiated with light is known as an internal photoelectric effect. The inventors of the present application have conducted intensive research and found that even when an electrically insulating polymer material such as a biological tissue equivalent plastic is irradiated with radiation, the current of the polymer material irradiated with radiation is also reduced. It was found that the value changed sufficiently to be taken out as an external signal, and the force was also found to have a linear linearity due to the unique correspondence between changes in radiation intensity, radiation dose, and output current value. . This is a completely new finding. In addition, the change in the current value causes the generation of dangling bonds due to the breakage of the polymer chain bonds by radiation near the inside or inside of the polymer, and carriers such as electrons are generated therefrom. It is considered that the external current can be obtained by drifting in the external electric field. When the current value changes due to the irradiation of radiation, it is confirmed that the current value also changes by irradiation of force β-rays (not electromagnetic waves), which is similar to the internal photoelectric effect from the viewpoint of the radiation phenomenon alone. Is considered to be different. In other words, in the case of ordinary polymer materials, the electrons that carry the charge are in a bound state that cannot move from the atoms that make up the molecule, 380ηπ! In the visible light region of ~ 780nm, it does not have enough energy to break its binding, so no current flows. It is considered that carriers are induced in the vicinity of the surface irradiated with radiation or near the surface. The radiation in the present invention is ionizing radiation and targets γ rays, j8 rays, α rays, and X rays.

[0019] Further, in the present invention, the polymer material is set to an inter-electrode distance at which an electrical resistance value between the electrodes is about 10 Ω or more, more preferably 10 ¹² Ω or more. Person who likes When measuring the exposure dose to the body, it is desirable to use biological tissue equivalent plastic. In this case, the radiation dose corresponds to the absorbed dose of the living tissue. According to this, the amount of absorbed radiation can be measured with a composition equivalent to or similar to that of a living body, and the amount of absorbed radiation to the human body can be further accurately measured.

[0020] Furthermore, in the present invention, it is preferable that the electrically insulating polymer substrate is made of a biological tissue equivalent plastic when being attached to the body surface or inserted into the body.

[0021] In addition, in the present invention, when used for measuring the exposure dose of a patient at the time of imaging by radiation irradiation or radiation irradiation treatment, the electrically insulating polymer substrate is used as the effective radiation to be irradiated. It is preferably composed of an electrically insulating polymer material having a permeability of about 90% or more in energy, and it is desirable to apply it to a patient in the form of a sheet, for example.

[0022] Further, in the present invention, when used in a window of a space that handles radiation, the electrically insulating polymer substrate is constituted by an electrically insulating polymer material having transparency to visible light. Is preferred.

[0023] Further, the radiation dosimetry apparatus according to the present invention is characterized by a radiation dosimetry element having at least a pair of electrodes on the surface or inside of an electrically insulating polymer substrate, and a radiation dosimetry element for the radiation. A voltage applying means for applying a voltage between a pair of electrodes; a current detecting means for detecting a current flowing between the electrodes; a dose acquiring means for converting the detected inter-electrode current force dose; and a display means for displaying the dose The radiation dose is measured by changing the output current value of the dosimetry element with linear uniqueness with respect to the radiation dose by irradiation with radiation.

[0024] According to such a configuration, when the electrically insulating polymer substrate of the radiation dose measuring element receives radiation in a state where a voltage is applied to the pair of electrodes by the voltage applying means, the electrically insulating polymer Since carriers are generated on the surface of the substrate and / or in the vicinity of the surface and the generated carriers flow to the positive and negative electrodes, radiation can be detected by detecting the weak current caused by the carriers by the current detection means. Then, it is possible to detect the radiation dose by measuring the weak current by the current detecting means. In the present invention, the dose measuring element is attached in the distal end of the catheter, and connected to a constant characteristic impedance line such as a microstrip line disposed in the tube of the catheter to connect the voltage applying means and the current detection. It may be configured to have a dose conversion means for converting the dose from the interelectrode current detected by this means, and a display means for displaying the dose.

[0026] Further, in the present invention, an electronic circuit including the dose measuring element, a calculation processing unit having a dose conversion function with a built-in current amplifier, and a storage unit for storing measurement data in a button-shaped small housing. A board, a small battery, an alarm device, and an external connector are built in, and the dose measuring element, the electronic circuit board and the small battery are connected via a pair of constant characteristic impedance lines. Anyway.

[0027] Furthermore, in the bottom of the shoe, an electronic circuit board including the dose measuring element, a calculation processing unit having a dose conversion function incorporating a current amplifier, and a storage unit for storing measurement data, and a small battery And an alarm device and an external connection connector, and the dose measuring element, the electronic circuit board and the small battery may be connected via a pair of constant characteristic impedance lines. .

The invention's effect

[0028] According to the present invention,

1) Since the radiation dose measuring element can be formed in any shape such as a curved surface or a spherical shape, it can be affixed to the human body or organ for radiation therapy to measure the absorbed dose in the body, or irradiation with diagnostic X-rays It is possible to measure the exposure dose. In this case, the absorbed dose can be predicted using an organ model case by forming it in the shape of a human body part or organ, or it can be measured in real time while irradiating with radiation.

2) It is also possible to measure the radiation dose in the radiation control area and the general environment with a tissue model that simulates the human body.

3) Compared with the prior art, the entire apparatus can be reduced in size, simplified and reduced in cost.

4) Measurements with excellent operational stability, reliability, and durability are possible even in high-intensity radiation environments.

5) Even in a wide voltage range (low voltage of 10V or less is acceptable) It is possible to detect the flow and measure the radiation dose.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a radiation dose measuring element 1 using an electrically insulating polymer material according to the present invention and a radiation dose measuring apparatus 2 using the same will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration of a radiation dose measuring apparatus 2 according to the present embodiment. The radiation dose measuring device 2 of this embodiment includes a radiation dose measuring element 1 for detecting the radiation dose, and a device main body 3 for controlling the radiation dose measuring element 1 and calculating the radiation dose 3. And a display device 4 for displaying the measurement result of the radiation dose. In this embodiment, the dose indicates a dose corresponding to the absorbed dose of a substance such as a living tissue.

First, the radiation dose measuring element 1 will be described. As a result of earnest research on the above-described problems, the inventors of the present application have found that an electric current flows by irradiating the surface of an electrically insulating polymer substrate composed of only an electrically insulating polymer material. In addition, it was found that the output current value has a linear uniqueness with respect to the dose of irradiated radiation. By using such a linear relationship between the current value and the radiation dose, the current value generated in the electrically insulating polymer substrate, or is detected by detecting a change in the voltage between the electrodes caused by the current. I came up with this invention that can measure the dose rate of the emitted radiation.

As shown in FIG. 1, the radiation dose measuring element 1 of the present embodiment is composed of a tissue-equivalent plastic or a material having properties equivalent to this, and is a polymer having electrical insulation properties at room temperature. The substrate 11 is composed of a pair of electrodes 12 and 12 provided on the surface of the electrically insulating polymer substrate 11. The electrodes 12 and 12 need not be limited to a pair. For example, the electrodes 12 and 12 may be formed on the lower surface side to form two pairs of electrodes 12 and 12.

[0033] The electrically insulating polymer substrate 11 is for generating a carrier and causing a change in conductance on the surface, in the vicinity of the surface thereof, in the interior thereof, or both by irradiation, and for tissue equivalent plastics. It can be molded with various polymer materials including The electrically insulating polymer substrate 11 is electrically insulative when not exposed to radiation. On the other hand, a minute current flows when irradiated with radiation, and the current value has a linearity proportional to the radiation dose.

[0034] The electrical insulating polymer substrate 11 in the present embodiment is more preferable because the electrical resistance value between the pair of electrodes is about 101 ^(> Ω or more ⁾ in order to detect a signal having a practical size due to radiation irradiation. The distance between the electrodes is set to about 10 ¹² Ω or more, and the resistivity of the electrically insulating material is generally about 10 ^{1 (>} Ω cm or more). The resistivity of the polymer material used for the substrate 11 is more preferably about 10 ¹⁴ Ωcm or more, preferably about 10 ¹² Qcm or more, if signal detection by irradiation is possible. For example, volume resistivity at around room temperature is 10 ¹⁶ Ωcm or more for polyethylene, polypropylene, polyimide, polycarbonate, etc., and 10 ¹⁵ to 10 ¹⁷ Ω for IOU IO Q CH ^ epoxy resin for phenol resin. cm, about 10 ¹⁴ Ωcm for polyester resin.

[0035] Here, the tissue equivalent plastic is an electrically insulating polymer material having a chemical formula (or mixing ratio) close to the composition of the elements (C, H, O, N, F, etc.) constituting the living tissue. It is (plastic) and has similar chemical composition, so it can be regarded as equivalent to living tissue when considering interaction with radiation. The composition of the tissue-equivalent plastic is similar to the elemental composition of living soft tissue and muscle tissue, and a physical quantity representing the amount of energy imparted as stopping power is equivalent to radiation particles having high energy. Examples of the tissue equivalent plastic include polycarbonate, acrylic resin, polyethylene, polyamide nylon, polyethylene terephthalate, water equivalent plastic, urethane resin, epoxy resin, polytetrafluoroethylene, and the like. In addition, since tissue equivalent plastics have properties as plastics, they can be formed into any shape and can easily cope with curved or complex shapes.

Next, the pair of electrodes 12 and 12 are composed of a positive electrode and a negative electrode, and are provided on the surface of the electrically insulating polymer substrate 11 at a predetermined interval as shown in FIG. It has been. Each of the electrodes 12 and 12 of this embodiment is formed as a metal thin film made of gold (Au) by using a thin film technique such as vacuum deposition. The pair of electrodes 12 and 12 are connected to the apparatus main body 3 via a predetermined cable. The arrangement of the electrodes 12 and 12 is not limited to the above configuration, but may be inserted into the electrically insulating polymer substrate 11 as described later. Next, the apparatus main body 3 will be described with reference to FIG. The apparatus main body 3 of the present embodiment includes a voltage application circuit 31 that applies a bias voltage between the electrodes 12 and 12 of the radiation dose measuring element 1 and a current detector 32 that detects a weak current flowing between the electrodes 12 and 12. And an amplification circuit 33 that amplifies the weak current detected by the current detector 32, a display drive circuit 34 that displays the display device 4, and the current detector 32, the amplification circuit 33, and the display drive circuit 34. 35 and a microcomputer 36 connected via 35.

As shown in FIG. 2, the voltage application circuit 31 is connected to the electrodes 12 and 12 of the radiation dose measuring element 1 by a predetermined cable. Further, it is connected to the microphone port computer 36 via the interface 35, and the applied noise voltage is adjusted. The bias voltage applied between the electrodes 12 and 12 is appropriately determined according to the material of the electrically insulating polymer substrate 11 and the distance between the pair of electrodes 12 and 12, and in this embodiment, about 1 to: DC of LOOV The voltage is set.

As shown in FIG. 2, the current detector 32 is connected to the positive electrode 12 of the radiation dose measuring element 1. In this embodiment, a solenoid coil (not shown) and a Hall element are included, and the Hall element detects a magnetic field line generated in the solenoid coil by a weak current from the positive electrode 12. Therefore, even a weak current is detected with high accuracy. Note that an inexpensive current operational amplifier may be used as the current detector 32.

[0040] The microcomputer 36 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and a CPU (Central Processing Unit), and various control means including a dose conversion means. Function as. In the ROM, a dose measurement program for measuring the radiation dose, a display control program for displaying on the display device 4 and the like are input and stored in advance. The dosimetry program incorporates a predetermined conversion formula or conversion table for calculating the dose of detected current value radiation. The conversion formula or conversion table is obtained for each dosimetry element 1 having a different configuration or material, and is proportional to the intensity of radiation and the current value in the electrically insulating polymer substrate 11 irradiated with the radiation. Determined by a linear relationship. The RAM stores the weak current value detected by the current detector 32 while being updated at a predetermined time interval (for example, 1 second). The CPU is based on the dosimetry program stored in ROM and the latest stored in RAM. Current value data is acquired, and the radiation dose is acquired by a predetermined conversion formula or conversion table. The acquired value is displayed on the display device 4 via the display drive circuit 34.

Next, the operation of the radiation dose measuring element 1 using the electrically insulating polymer material of the present embodiment and the radiation dose measuring apparatus 2 using the same will be described.

First, the radiation dose measuring element 1 is set at a position where radiation is irradiated. At this time, since the radiation dose measuring element 1 can be thinly formed in an arbitrary shape, it can be attached along the surface shape of the irradiated object. In addition, for example, when a model of a predetermined part of the human body (such as an organ) is formed of tissue equivalent plastic, and electrodes 12 and 12 are formed on the surface of this model, the dose of radiation applied to that part is monitored. Configured as radiation dosimetry element 1

After the radiation dose measuring element 1 is set at a predetermined position, a predetermined bias voltage is applied to the pair of electrodes 12 and 12 by the voltage application circuit 31. As a result, an almost constant weak current flows through the electrically insulating polymer substrate 11 to the positive electrode force and the negative electrode. The current detector 32 constantly detects the weak current, and the detected current value is amplified by the amplifier circuit 33 and then input to the microcomputer 36 via the interface 35. The microcomputer 36 stores the acquired latest current value while updating it in the RAM at predetermined time intervals. The stored current value is acquired sequentially by the CPU, and the increase or decrease is monitored.

As described above, when radiation is applied to the surface of the electrically insulating polymer substrate 11 with a bias voltage applied to the radiation dose measuring element 1, the vicinity of the surface of the electrically insulating polymer substrate 11 is irradiated. A career occurs. As a result, the generated carriers are caused to flow to the electrodes 12 and 12 by the noise voltage, so that the current flowing to the electrodes 12 and 12 slightly increases. When the CPU detects a small current increase due to radiation irradiation, the current increase and the above-mentioned conversion formula ヽ is based on the conversion table and the radiation incident on the electrically insulating polymer substrate 11 is detected. Calculate the dose. The calculated radiation dose is displayed on the display device 4 in the form of numerical values and graphs.

[0045] Next, an experimental example according to the radiation dose measuring element 1 of the present embodiment will be described. The inventors of the present patent application use alumina (Al 2 O 3) or tissue-equivalent plastic as the insulating substrate before applying the electrically insulating polymer substrate 11 to the dosimetry element 1. A basic experiment was conducted in which a titanium oxide thin film layer, an alumina thin film layer, and an oxide-zirconium thin film layer were formed on these substrates and irradiated with radiation. As a result, it is disclosed in Japanese Patent Application No. 2004-151087. However, in this case, it was not necessary to form the metal oxide thin film by further experiments, and the electrically insulating polymer was not formed. An experimental result was obtained that the output current had a linear uniqueness with respect to the radiation dose by using the substrate 11 made of only the material. Hereinafter, each experimental example will be described.

[0046] "Experiment 1"

An experimental example according to the present invention will be described. Fig. 3 is a schematic diagram of the measurement circuit of radiation detector 1 (also a radiation dosimetry device) used in the experiment. The radiation detection element 1 includes a substrate 11 made of various electrically insulating polymer materials, and a pair of linear electrodes 12, which are provided on the electrically insulating polymer substrate 11 so as to face each other at an interval. It consists of twelve. The thickness of the electrically insulating polymer substrate 11 was 1 mm, and the vertical and horizontal lengths were each 10 mm. The electrodes 12 and 12 are formed at the end of the substrate 11 and have a length of 10 mm, a width of 3 mm, a thickness of 200 to 300 nm, and an interelectrode distance of 6 mm.

[0047] Materials for the electrically insulating polymer substrate 11 include plastic water (registered trademark of CIRS, USA), polycarbonate, polyimide, polyetheretherketone (PEEK: registered trademark of Victrex, UK), Teflon (registered) Trademark) (DuPont, USA). Plastic Water (registered trademark) has a specific gravity of 1.039 (g / cm ³ ) and has a specific gravity very close to that of water, and its composition ratio is 0.599 for carbon C, 0.235 for oxygen O, Hydrogen H force SO. 078, Nectar N force SO. 018, Kanoreshikum Ca force 0. 068, Element C1 force 0.002. Polyimide is a wholly aromatic polyimide, using TI-3000 (Toray), and its specific gravity is about 1.4 (g / cm ³ ). , Hydrogen H is 0.300, oxygen O is 0.125, and nitrogen N is 0.05. The specific gravity of polycarbonate is about 1.2 (g / cm ³ ). On the other hand, the experimental power supply was a DC stabilized power supply with a built-in electometer with 0 ~: L00V output, and the current output was measured with a galvanometer (electrometer) G.

[0048] In Experimental Example 1, first, an experiment of irradiating X-rays was performed. The X-ray irradiation device uses Stabilipan II (Siemens), and the irradiation conditions are tube voltage 100 kV and effective voltage 57 keV. , Tube current 20 mA, irradiation time 60 sec, irradiation distance 40-: L 10 cm. The applied voltage was set to 10V-constant.

FIG. 4 is a graph showing the relationship between the irradiation dose rate and the output current value when various types of electrically insulating polymer substrates 11 are irradiated with X-rays. The horizontal axis of the graph shows the X-ray irradiation dose rate, and the vertical axis shows the output current value. As is apparent from this graph, the current value generated in the substrate 11 made of various electrically insulating polymer materials is uniquely determined by showing linearity proportional to the X-ray irradiation dose rate. Among the polymers used in this experiment, polycarbonate showed the highest output current, and a current value of about 35 OpA was output at an X-ray irradiation dose rate of 35 X 10 ^_4 (C / kg / min). . The average sensitivity, which is the inclination based on the proportional characteristics of this polycarbonate, is about 90 [nA / (C / kg / min)]. On the other hand, PEEK (registered trademark), plastic water (registered trademark) and polyimide have a smaller output current value than polycarbonate and Teflon (registered trademark), and show an output current value of about 150 pA. Therefore, it is a problem as a sensor. In particular, it has been confirmed that each electrically insulating polymer material has a sufficient output even at a voltage of 10V, and an output current can be obtained even at IV. It can be utilized as a practically preferable. Since the irradiation dose and absorbed dose are almost proportional in the soft tissue of the living body, such as muscles and internal organs, the results in the above graph are similar to the relationship between the generated current value and the absorbed dose. It can be applied and can be said to have proportional linearity.

[0050] "Experiment 2"

Next, as Experimental Example 2, the characteristics of the output current value with respect to the irradiation dose rate when γ-rays of radiation were irradiated were examined. The dimensions of radiation dosimeter 1 and the type of electrically insulating polymer material are the same as in Experimental Example 1. Further, gamma ray irradiation apparatus is gamma ray source 60Co using Toshiba Cobalt 60 rotation therapy apparatus (manufactured by Toshiba), irradiation conditions, average _Ύ ray energy 1. 25 MeV, irradiation time 60 sec, irradiation distance 65 125 cm. The applied voltage is 10 V.

FIG. 5 shows the results of Experimental Example 2. FIG. 5 is a graph showing the relationship between the irradiation dose rate and the output current value when γ rays are irradiated to various electrically insulating polymer substrates 11. Experimental example 1 As in the case of X-rays, it can be seen that the current values generated in the substrate 11 by various electrically insulating polymer materials are uniquely determined by showing a proportional relationship with the irradiation dose rate of γ-rays. In addition, when the output current value of polycarbonate, Teflon (registered trademark) and PEEK (registered trademark) is about 9 X 10 " ⁴ (C / kg / min), the current value is about 35pA to 40pA. In contrast, the current value of polyimide was about 8 pA and the plastic water (registered trademark) was about 14 pA for the same radiation dose rate, but 10 V for any electrically insulating polymer material. Since the current value that can be measured sufficiently by the applied voltage is output, each of them has practicality as a sensor.The average sensitivity of the polycarbonate is about 30 [nA / (C / kg / min)].

[0052] Experimental Example 3

Next, an experiment was conducted to determine whether the output current value has a linearity proportional to the radiation dose even when the electrically insulating polymer substrate 11 is in a vacuum atmosphere. This is because the proportional characteristics of the irradiation dose and the current value in Experimental Example 1 and Experimental Example 2 are affected by the ambient atmosphere, for example, the ionization of the gas existing in the vicinity of the electrically insulating polymer substrate 11. This is an experiment to confirm this. As the material for the electrically insulating polymer substrate 11, polycarbonate showing the highest current output was used, and X-rays were irradiated under the same conditions as in Experimental Example 1 except under vacuum conditions. The degree of vacuum was 10 ^_3 T _OTr order ₀

FIG. 6 is a graph showing the results of Experimental Example 3. The horizontal axis is the radiation dose rate, and the vertical axis is the output current value. From this graph, it can be seen that the output current value has a proportional linearity to the radiation dose rate even in a vacuum atmosphere. When the output current value is about 20 X 10 " ⁴ (C / kg / min) X-ray irradiation dose rate (dose rate on the vacuum chamber surface), it is about 13 pA and the result in the atmosphere (about 230 pA) This is thought to be because the radiation dose reaching the dosimetry element 1 is attenuated by setting the radiation dosimetry element 1 in the vacuum chamber.

[0054] Experimental Example 4

Next, the response characteristics of the external output current to X-ray ONZOFF were investigated. The electrically insulating polymer material uses polycarbonate and the X-ray irradiation time is 60 seconds. External application Voltage is constant at 10V, X-ray intensity is 8 X 10 " ⁴ (C / kg / min), 9 X 10" ⁴ (C / kg / min), ll X 10 ^_4 (C / kg / min), ^{13 X 10_ 4 (C / kg} / min) and is sequentially changed, to measure the output voltage current values at that time.

FIG. 7 is a graph showing the results of Experimental Example 4. The horizontal axis represents the X-ray irradiation time, and the vertical axis represents the output current value. According to Fig. 7, the output current value is about 115pA when the X-ray intensity is 8 X 10 ^_4 (C / kg / min), and about 130pA when 9 X IO— ⁴ (C / kg / min). it can be seen that shows the 11 X 10 ^_4 current value of about 185pA when (C / kg / min) when about ^{155pA, 13 X 10_ 4 (C} / kg / min). It can be seen that when the X-ray intensity is increased in this way, the amount of charge carriers generated in the electrically insulating polymer substrate 11 increases, and the output current increases. It can also be seen that the response speed of the X-ray source to O NZOFF is within 1 second.

Next, an embodiment using the radiation detection element 1 having other constituent forces will be described.

In each of the above-described embodiments, the radiation detection element 1 in which the electrodes 12 and 12 are arranged on the surface of the electrically insulating polymer substrate 11 is used. However, in the following experimental example, as shown in FIG. An experiment was conducted to determine whether the same effect can be obtained by using the radiation detection element 1 in which 12 and 12 are inserted into the electrically insulating polymer substrate 11.

[0057] "Experiment 5"

In this Experimental Example 5, an experiment was conducted to confirm whether or not the force is such that a practical current is output even when the pair of electrodes 12 and 12 are inserted inside instead of the surface. As shown in FIG. 8, a pair of electrodes 12 and 12 were configured by inserting a needle electrode having a maximum diameter of 0.5 mm into a 10 mm × 10 mm × lmm size radiation detection element 1 and having a maximum diameter of 0.5 mm in the lmm thickness portion. The distance between electrodes 12 and 12 is 6 mm. An experiment was performed by applying a voltage of 1 to 100 V to the electrodes 12 and 12. X-ray irradiation dose was constant ^{35 X 10_ 4 (C / kg} / min).

FIG. 9 is a graph showing the results of Experimental Example 5. The horizontal axis represents the interelectrode voltage, and the vertical axis represents the output current value. According to Fig. 9, when the number of charged particles generated in the radiation detection element 1 at a fixed radiation dose is considered to be constant, the charged particle velocity V increases by increasing the applied voltage to IV ~: LOOV. It can be seen that the current increases according to the relational expression of current density i = nev (AZm ² ). Where n is the density of charged particles, e is the charge amount of charged particles, V is the velocity of charged particles, and ν = μ (VZd). Where μ is the mobility of charged particles. But Thus, it can be seen that even when the electrodes 12 and 12 are inserted into the electrically insulating polymer substrate 11, the function as the dosimetry element 1 can be obtained in the same manner as that formed on the surface.

[0059] Experimental Example 6

Next, the response characteristics of the external output current with respect to X-ray ONZOFF were investigated for the radiation detection element 1 of the type in which the electrodes 12 and 12 were inserted. The X-ray irradiation dose was set to a constant of 35 X 10 " ⁴ (C / kg / min), and X-rays were applied for 5 minutes at an applied voltage of 10V.

FIG. 10 is a graph showing the results of Experimental Example 6. The horizontal axis represents the X-ray irradiation time, and the vertical axis represents the output current value. As can be seen from FIG. 10, the radiation detection element 1 generates a constant and stable output current with respect to the irradiation time. Therefore, a stable signal can be guaranteed even for long-term measurements. In Fig. 10, spike-like signals are seen at 1 minute and 5 minutes. This is an electrical noise that generates X-ray generator power when X-ray irradiation is turned on and off.

[0061] According to each experimental example as described above, when various types of electrically insulating polymer substrates 11 are irradiated with radiation such as X-rays or γ-rays, the current value generated between the electrodes 12 and 12 is the radiation. It was found that there is a proportional relationship with the irradiation dose. Further, based on the results of the above experimental example, if the above-described phenomenon is mainly caused by the reaction of electrons (secondary charged particles) generated in the electrically insulating polymer substrate 11, it is configured from the electrically insulating polymer substrate 11. It is considered that the same results can be obtained even when the dose measuring element 1 is irradiated with j8 rays or α rays. The measured current value strongly depends on the material of the electrically insulating polymer substrate 11, and if a tissue equivalent plastic is used, a value equivalent to the radiation dose to the human tissue can be estimated.

[0062] Experimental Example 7

Next, a suitable thickness of the electrically insulating polymer substrate 11 used as the dose measuring element 1 was calculated using a general-purpose Monte Carlo simulation code EGS4. 12 and 13 are graphs showing the results of Experimental Example 7. The horizontal axis represents the irradiation depth for the tissue equivalent plastic used in the present embodiment, and the vertical axis represents the energy accumulation amount. Fig. 12 shows the energy accumulation with respect to the irradiation depth under the condition of 1.25 MeV Co60 (γ-ray) irradiation, and Fig. 13 shows the case of 200 keV photon irradiation corresponding to X-ray irradiation. Shows the amount of energy stored with respect to the irradiation depth.

[0063] Referring to FIG. 12, Co60, which is a γ-ray, is saturated at 3 to 4 mm. Therefore, when applied to the electrically insulating polymer substrate 11, it is preferable to configure the thickness to be equal to or greater than this saturation depth. Good. On the other hand, as shown in FIG. 13, when 200KeV photons assuming X-rays are irradiated, saturation occurs at 0.1 mm or more, so it is preferable to configure a thickness larger than that! /.

[0064] Considering the above results, when measuring the dose of γ rays, the electrically insulating polymer substrate 11 having a thickness of 3 to 4 mm or more preferably measures the dose of X rays. In this case, the electrically insulating polymer substrate 11 having a thickness of 0.1 mm or more is preferable. In the present embodiment, in which the thinner one is preferable for taking advantage of the good workability of the polymer material, an electrically insulating polymer substrate 11 having a thickness of lmm is used in the experiment.

[0065] When the electrical resistance between the electrodes of the electrically insulating polymer substrate 11 used in this experimental example was measured, all were 5 x 10 ¹² Ω or more.

[0066] According to the present embodiment as described above, the following effects can be obtained.

(1) Since electrically insulating polymer materials such as tissue equivalent plastics can be formed into any shape such as the human body or organ, measurement can be performed using conventional proportional counters using tissue equivalent gas or ionization chambers in water. Compared to this, the measurement accuracy and convenience are expected to improve significantly. In particular, since the main body of the dose measuring element 1 can be formed of only an electrically insulating polymer material, it is easy to manufacture and the cost can be reduced. For example, it is formed into a thin curved surface and attached directly to the human body, etc., and the absorbed dose in the body is measured while performing radiation therapy, or there is a dose measuring element 1 attached to the tip of the catheter and inserted into the body, In vivo (in blood) absorbed dose during surgery can be measured, and it can be said that the applicability and feasibility are extremely high.

(2) An organ model is made of tissue equivalent plastic, and it is possible to know beforehand by experiment how much radiation dose is absorbed in which part. In this case, according to the spherical radiation dose measuring element 1 as shown in FIG. 11, the radiation dose can be measured not only in one direction but also in multiple directions. The effect is that measurement can be performed without direction dependency, such as radiation dose measurement not only on the front side but also on the back side.

(3) Since electrically insulating polymer materials such as tissue equivalent plastics are solid, Become a big device like tissue equivalent gas! /, And can be downsized because it can detect the current value and measure the radiation dose even at low voltage. Furthermore, it has the effect of being able to perform measurements with excellent operational stability, reliability, and durability even under high-intensity radiation environments.

(4) The radiation dose can be measured by detecting a large signal current with a small dark current even in a wide voltage range including a low voltage of 10V or less.

(5) It is also possible to measure the radiation dose in the radiation control area and the general environment with a tissue model that simulates the human body.

It should be noted that the radiation dose measuring element 1 and the radiation dose measuring device 2 using the radiation measuring element 1 according to the present invention are not limited to the above-described embodiments, but can be changed as appropriate.

[0068] For example, an alarm device may be provided for notifying that radiation of a predetermined value or more has been detected. According to this, even if excessive radiation is irradiated to the human body, since the alarm device issues an alarm, the irradiation can be stopped immediately.

[0069] Next, more specific examples of the radiation dose measuring element 1 and the dose measuring apparatus 2 according to the present invention will be described.

[0070] "Example 1"

As shown in FIG. 14, the first embodiment is an example in which the dose measuring element 1 is configured in a sheet shape when used in X-ray imaging or CT scan imaging, and the patient's exposure dose by X-ray imaging is measured. It is.

In Example 1, the electrically insulating polymer substrate 11 is added in the form of a sheet with an electrically insulating polymer material having a transmittance of about 90% or more of the effective energy of radiation to be irradiated. It is preferable that the electrically insulating polymer substrate 11 has a thickness of about 100 m to 1 mm and has a flexibility that can be easily deformed with a size force S 10 cm × 10 cm or more. For example, by processing polyethylene into a sheet shape, embedding a pair of electrodes 12 and 12 at both ends, and connecting it to the device body 3 via coaxial cables 41 and 41, which are a pair of constant impedance wires The dosimetry apparatus 2 is configured. The main unit 3 has a voltage application control function, a current detection / display function, a current-one-dose rate conversion function, a data storage function, and a recording function. Then, a predetermined voltage is applied between the electrodes 12 and 12 by the device body 3 to By monitoring the flow value and converting it to exposure dose, it is possible to manage the exposure dose of the whole body of patient p in real time. Also, place the electrically insulating polymer substrate 11 only on specific parts of the patient's genitals, etc., and manage the exposure dose for each organ.

[0072] When used in the embodiment 1, the characteristics required for determining the material and size of the substrate 11 include, in addition to electrical insulation and flexibility, the image quality of the transmitted image. It is desirable to select a material and thickness that can ensure 90% or more transparency in the effective energy of the X-ray generator.

[0073] Sarako, although not shown, is a clean bench used when handling high-level radioactive substances by hand by providing a function of transparency to visible light as a characteristic of the electrically insulating polymer substrate 11. It is also possible to monitor the exposure dose of workers in real time by applying it to windows such as glove boxes.

[0074] "Example 2"

Next, Example 2 of the present embodiment will be described. The second embodiment is an example in which the dose measuring element 1 is attached to the distal end of the catheter so that it can be inserted into a blood vessel, and the dose of blood or the dose of a specific organ can be measured.

As shown in FIG. 15, a cylindrical electrically insulating polymer substrate 11 is attached to the distal end of the catheter 50, a pair of electrodes 12 and 12 are embedded in the substrate 11, and the pair of electrodes 12 and 12 are attached. Connect to a pair of microstrip lines 52 and 52 arranged in the tube 51 of the catheter 50, and connect the pair of microstrip lines 52 and 52 to a pair of coaxial cables 41 and 41 to connect to the main body 3 of the apparatus. The dosimetry apparatus 2 is configured with this. As in Example 1, the main body 3 has a voltage application control function, a current detection / display function, a current-one dose rate conversion function, and a data storage / recording function.

[0076] By applying a predetermined voltage and monitoring the current value by the apparatus main body 3 and converting it to an exposure dose, it becomes possible to measure absorbed doses of various organs and tissues in the human body. The catheter 50 to which such a function is added makes it possible to manage the radiation dose of each organ at the distal end of the catheter during an interventional radiology (IVR) procedure.

[0077] "Example 3" Next, Example 3 of the present embodiment will be described. In this third embodiment, the dose measuring element 1 is built in the button-shaped housing 60 so that it can be easily attached as a part of the clothes of the worker, so that the radiation handling worker can receive the dose in real time. This is an example that enables measurement.

As shown in FIG. 16, the dose measuring apparatus 2 of Example 3 includes a pair of electrodes 12 and 12 embedded in a cylindrical tubular casing 60 having a diameter of about 20 mm and a thickness of about 10 mm. A disk-shaped electrically insulating polymer substrate 11, an electronic circuit board 61, a small battery 62 composed of a button battery, a coin battery, etc., an alarm device 63, and an external connection connector 64 are incorporated. The electronic circuit board 61 is provided with a CPU 65 having a dose conversion function with a built-in current amplifier 33, and a measurement data storage electronic circuit element 66 such as an EPROM. The small battery 62 and the measurement data storage electronic circuit element 66 are connected via a microstrip line 52, 52 which is a pair of specific impedance lines.

[0079] Then, the dose measurement device 3 is configured by connecting to the dose management device 67 installed outside via the external connection connector 64, and the integrated dose can be measured instantaneously at an arbitrary time. it can. Therefore, it is possible to manage individual exposure dose in the radiation control area. In addition, the measurement data storage electronic circuit element 66 can be reset to the initial value by the exposure dose management device 67, so that one dose measurement element 1 can be used as many times as a personal dosimeter. can do.

[0080] Further, by setting a dose threshold for the CPU 65 having a dose conversion function with a built-in current amplifier 33 and controlling the alarm device 63 to be activated when the accumulated dose exceeds the threshold, the worker can be controlled. A warning of exposure can be issued in real time. As the alarm device 63, a sound generating device such as a buzzer, a visible light generating device such as a semiconductor light emitting element, or a device using both of them can be considered. The threshold value can be changed by the exposure dose management device 67. Note that the disk-shaped dose measuring element 1 of Example 3 is an example, and may be formed in a square cross section, a hexagonal cross section, or the like.

[0081] "Example 4"

Next, Example 4 of the present embodiment will be described. In this example 4, the sole 70 of the shoe 70 This is an example in which the dose measuring element 1 is built in to measure the exposure dose of the shoe sole 71, and radiation damage can be prevented from spreading due to the radioactive material adhering to the shoe sole of the worker.

As shown in FIG. 17, a flexible electrically insulating polymer substrate 11 having a pair of electrodes 12 and 12 embedded in a shoe sole 71 is embedded, and an electronic circuit board 61 is embedded in a heel portion of a shoe 70. A dosimetry device is configured by incorporating a small battery 62 and an alarm device 63. On the electronic circuit board 61, a CPU 65 having a dose conversion function with a built-in current amplifier 33 and a measurement data storage electronic circuit element 66 such as an EPROM are attached, and the electrically insulating polymer board 11, the CPU 65 and the small battery 62 are mounted. Are connected via a pair of coaxial cables 41, 41.

[0083] A threshold value for exposure dose is set in the CPU 65, and the alarm device 63 is activated when the cumulative exposure dose exceeds the threshold value. With this dosimetry device 3, it is possible to monitor radiation contamination of the floor in the radiation control area in real time. By using such shoes 70, it is possible to immediately notify the danger to the worker and to prevent the spread of contamination. In the case of Example 4, the alarm device 63 is preferably a sound generator such as a buzzer. In addition, it is desirable to embed a lead thin film in the parts other than the sole 71 in order to shield radiation from other than the floor. Further, similarly to the third embodiment, an external connection connector 64 may be provided in the dose measuring apparatus 2 so that measurement data can be exchanged with an external apparatus and a threshold value can be changed for generating an alarm.

[0084] As described above, the dose measuring element 1 and the dose measuring device 2 of the present embodiment are not limited to the above embodiments, and can be applied to various modes affected by radiation. Brief description of

FIG. 1 is a schematic diagram showing an embodiment of a radiation dose measuring apparatus according to the present invention.

FIG. 2 is a block diagram showing an apparatus main body of the present embodiment.

FIG. 3 is a schematic diagram of a radiation detection element in Experimental Example 1.

4) A graph showing the relationship between the X-ray irradiation dose rate (horizontal axis) and the output current value (vertical axis) in Experimental Example 1.

[Fig.5] Shows the relationship between γ-ray irradiation dose rate (horizontal axis) and output current value (vertical axis) in Experimental Example 2 It is a graph.

FIG. 6 is a graph showing the relationship between the X-ray irradiation dose rate (horizontal axis) and the output current value (vertical axis) on the vacuum chamber surface in a vacuum atmosphere in Experimental Example 3.

7) A graph of response characteristics showing the relationship between the X-ray irradiation time (horizontal axis) and the output current value (vertical axis) in Experimental Example 4.

[8] FIG. 8 is a schematic diagram showing an embodiment using a radiation detection element having another configuration.

[9] A graph showing the relationship between the interelectrode voltage (horizontal axis) and the output current value (vertical axis) in Experimental Example 5.

[10] This is a graph showing the relationship between the X-ray irradiation time (horizontal axis) and the output current value (vertical axis) in Experimental Example 6.

[11] FIG. 11 is a diagram showing variations in the shape of the radiation dose measuring element according to the present invention. 12] A graph showing the relationship between Co60 irradiation depth (horizontal axis) and energy storage (vertical axis) in Experimental Example 7.

13] A graph showing the relationship between the irradiation depth (horizontal axis) of 200KeV photons and energy storage (vertical axis) in Experimental Example 7.

[14] FIG. 14 is a schematic diagram showing Example 1 in which the dosimetry apparatus according to the present invention is applied in the form of a sheet.

[15] FIG. 15 is a schematic diagram showing Example 2 in which the dosimetry apparatus according to the present invention is applied to a catheter.

FIG. 16 is a schematic view showing Example 3 in which the dose measuring apparatus according to the present invention is applied to a button-shaped housing.

圆 17] It is a schematic diagram showing Example 4 in which the dose measuring apparatus according to the present invention is applied to shoes. Explanation of symbols

1 Radiation dosimetry device

2 Radiation dosimetry equipment

3 Main unit

4 Display device

11 Electrically insulating polymer substrate electrode

Voltage application circuit

Current detector

Amplifier circuit

Display drive circuit

interface

Microcomputer Coaxial cable

Force Tetenore

Tube of force tensioner Microstrip line Button-shaped housing

Electronic circuit board

Small battery

Alarm device

External connector

CPU

Measurement data storage electronics circuit dose management equipment shoes

Shoe sole

Claims

The scope of the claims

[1] A highly insulating material characterized by comprising a substrate made of a polymer material having electrical insulation properties at room temperature and at least a pair of electrodes provided on or inside the electrically insulating polymer substrate. Radiation dosimetry element using molecular materials.

[2] In Claim 1, the electrically insulating polymer substrate is characterized in that the output current value has linear uniqueness with respect to the radiation dose by irradiation of radiation. Radiation dosimetry element.

[3] In claim 1 or 2, the electrically insulating polymer substrate is configured to have an inter-electrode distance such that an electrical resistance value between the electrodes is about ΙΟ ^ Ω or more. Radiation dose measuring element.

[4] In claim 1 or 2, the electrically insulating polymer substrate is configured to have an interelectrode distance in which an electrical resistance value between the electrodes is about 10 ¹² Ω or more. Radiation dose measuring element.

[5] In claim 1 or claim 2, the electrically insulating polymer substrate is composed of a living tissue equivalent plastic force, and is applied to a body surface or inserted into the body. Radiation dose measuring element.

[6] In claim 1 or claim 2, when used for measurement of exposure dose in transmission imaging or radiation treatment by radiation irradiation, the electrically insulating polymer substrate is used to measure the effective radiation. A radiation dosimetry element comprising an electrically insulating polymer material having a permeability of about 90% or more in terms of energy.

[7] In claim 1 or claim 2, when used for a window in a space for handling radiation, the electrically insulating polymer substrate is made of an electrically insulating polymer material having transparency to visible light. A radiation dose measuring element characterized by that.

[8] The radiation dose measuring element according to any one of claims 1 to 7, and

Voltage applying means for applying a voltage between a pair of electrodes of the radiation dose measuring element; current detecting means for detecting a current flowing between the electrodes;

A dose conversion means for converting a dose from the detected interelectrode current;

A radiation dose measuring apparatus comprising: a display means for displaying a dose.

[9] The dose measuring element according to any one of claims 1 to 4 is attached to the distal end of the catheter, and the voltage applying means and the current detection are connected to a certain characteristic impedance line arranged in the catheter tube. A radiation dose measuring apparatus comprising: a dose conversion means for converting a dose from an inter-electrode current detected by the means, and a display means for displaying the dose.

[10] A dose measurement element according to any one of claims 1 to 4, a calculation processing unit having a dose conversion function with a built-in current amplifier, and a storage unit for storing measurement data in a button-shaped small housing An electronic circuit board with a small battery, an alarm device, and an external connection connector are built in, and the dose measuring element, the electronic circuit board and the small battery are connected via a pair of constant characteristic impedance lines. Radiation dose measurement device characterized by being configured as above.

[11] The dose measuring element according to any one of claims 1 to 4, an arithmetic processing unit having a dose conversion function incorporating a current amplifier, and a storage unit for storing measurement data are provided in a shoe bottom. The electronic circuit board, the small battery, the alarm device, and the external connector are built in, and the dose measuring element, the electronic circuit board and the small battery are connected via a pair of constant characteristic impedance lines. A radiation dose measuring device characterized by