JPWO2006104046A1 - Radiation dosimetry element and radiation dosimetry device using electrically insulating polymer material - Google Patents

Abstract

Radiation dose using an electrically insulating polymer material that is excellent in processability, measures the dose in a state closer to living tissue, and can detect a large signal current in a wider voltage range (for example, a low dark voltage of 10 V or less). In order to achieve this object, a substrate 11 made of a polymer material having electrical insulation properties at room temperature and a surface or inside of the electrical insulation polymer substrate 11 are provided. When the substrate 11 is irradiated with radiation, an output current value having linear uniqueness with respect to the radiation dose rate is obtained.

Description

  The present invention relates to a radiation dosimetry element and a radiation dosimetry device, and in particular, an in vivo absorbed dose in radiation therapy, an exposure dose due to irradiation with diagnostic X-rays, an exposure dose in a radiation control area, an exposure dose due to general environmental radiation, etc. The present invention relates to a radiation dosimetry element and a radiation dosimetry apparatus using an electrically insulative polymer material suitable for measuring the radiation.

  Conventionally, techniques for measuring the absorbed dose, irradiation dose, radiation intensity, and the like of radiation have been proposed. For example, Japanese Patent Application 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 a pulse output from the linear electrode. And when using a proportional counter as a biological tissue model, it is measured by enclosing a biological tissue equivalent gas inside the counter.

  Japanese Laid-Open Patent Publication No. 2004-20249 proposes a radiation detection apparatus using an ionization chamber (Patent Document 2). In this radiation detection apparatus, a center electrode is provided in an ionization chamber filled with gas. And the intensity | strength of the radiation is measured based on the quantity of the ion ionized and produced in gas by the radiation which injected in the ionization chamber. When using an ionization chamber as a living body model, a finger-type ionization chamber is inserted into an insertion hole leading to a water-filled tank, and the radiation dose is measured assuming that it is equivalent to a living tissue. .

  Furthermore, a radiation detector described in US Pat. No. 6,278,117 discloses a “active polymeric layer” in which a metal electrode is wired on a “polymeric substrate” and the metal electrode is covered. (Active polymer layer) "is formed (Patent Document 3). And it is supposed that a radiation dose will be measured based on the electric current change in the "active polymeric layer" at the time of irradiation.

  The radiation sensor described in JP-A-5-107360 is composed of “an organic polymer substance containing halogen” and “polyaniline” (Patent Document 4). And the irradiation dose is calculated | required using the electrical conductivity of this "polyaniline" depending on the irradiation dose of a radiation.

  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 coating (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 the conductivity and resistance change. ing.

  Furthermore, 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). And the amount of irradiation is detected using the fact that the resistance value decreases as the amount of radiation irradiation increases.

JP 9-167594 A JP 2004-20249 A US Pat. No. 6,278,117 JP-A-5-107360 JP-A-2-143188 JP-A 62-299780

However, the conventional radiation measurement apparatus including the inventions described in Patent Document 1 and Patent Document 2 described above has the following problems.
(1) In a conventional apparatus for measuring a tissue absorbed dose, a tissue equivalent gas or water is used assuming a biological tissue model. However, since the human body is originally grasped 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. 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 measured with curved shapes such as human body parts or organs, spherical shapes, and complex shapes. 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 tissue equivalent gas of a volume equivalent to a living tissue to be measured, the counter 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-Gray principle that takes into account the physical properties of the wall material such as the gas used and build-up cap. The calculation process is complicated.
(5) In proportional counters and ionization chambers, the applied voltage is as high as ± (500 V to 800 V), and a special power source is required.

  On the other hand, radiation detectors using semiconductor elements are also known, but in high-intensity radiation environments, there is a problem that semiconductor elements are electrically broken or deteriorated, resulting in poor durability, and radiation dosimetry Not suitable as an element.

  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. Molecular layer) ”. For this reason, FIG. As shown in FIG. 2, there is a problem that the manufacturing process is increased with a complicated structure, and the cost is increased.

  Further, in Patent Document 3, FIG. As shown in FIG. 2, the metal electrodes are complicatedly wired at extremely small intervals, so that it is considered that the output current (hereinafter referred to as “dark current”) when not irradiated with radiation increases. For this reason, FIG. As shown in FIG. 4, in the range where the applied voltage is 1 V or more, the output current value when irradiated with radiation overlaps with the dark current or is lower than the dark current. In addition, FIG. As shown in FIG. 5, the resistance ratio (radiation OFF / radiation ON) is 1.0 or less in the range where the applied voltage is 4 V or more. In other words, when the applied voltage is in the range of 1 V or more, the dark current is larger than the signal current that increases when radiation is applied, so that the signal current cannot be determined and is difficult to use as a radiation detector.

  Furthermore, the radiation detection elements described in Patent Documents 4 to 6 are intended for conductive polymers and are not composed of only polymer materials. That is, Patent Document 4 synthesizes “polyaniline” to “organic polymer substance containing halogen”, and Patent Document 5 applies “composition” to a pair of electrodes provided on an insulating substrate. Patent Document 6 adds a “conductivity-imparting agent” to a polymer or rubber, both of which are directed to a conductive polymer.

  The present invention has been made to solve such problems, and has an object of obtaining at least one of the following effects. In other words, the radiation measuring element is made of solid as various polymer materials such as tissue equivalent plastic instead of gas, so that it can be miniaturized, simplified and reduced in cost, and can be molded into any shape. 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 adopting a polymer material having electrical insulation properties at room temperature, even in a wide voltage range (for example, a low voltage of 10 V or less is acceptable), a large signal current can be detected with a small dark current and used as a dosimetry element. An object of the present invention is to provide a radiation dosimetry element and a radiation dosimetry apparatus using an insulating polymer material.

  The present inventors have already disclosed in Japanese Patent Application No. 2004-151087 a dose measurement in which a thin film layer made of a semiconductor or an insulator is formed on the surface of a base member made of a tissue equivalent plastic, and a pair of electrodes is provided on the thin film layer. An element has been invented, and it has been proposed that conventional problems can be solved. And this time, the inventors proceeded further research, and even with an element composed only of an electrically insulating polymer material without forming the above-described semiconductor or insulator thin film layer, the radiation dose and the output current It was possible to confirm the operation as a radiation sensor. According to this, the moldability is remarkably excellent, and the cost can be drastically reduced, which is highly practical. In addition, since the polymer material is close to a low atomic number substance in living tissue, there is also an advantage that it is easy to estimate the absorbed dose of the living body.

  Therefore, the radiation dosimetry element using the electrically insulating polymer material according to the present invention is characterized by a substrate composed of a polymer material having electrical insulation properties at room temperature and the surface of the electrically insulating polymer substrate. Alternatively, it has at least a pair of electrodes provided inside.

  In the present invention, the electrically insulating polymer substrate has an output current value that is linearly unique with respect to the radiation dose when irradiated with radiation.

  Here, the mechanism of the present invention will be described. A phenomenon in which a photovoltaic effect of an insulator or semiconductor irradiated with light occurs 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 the current value of the polymer material irradiated with radiation is also an external signal by irradiating the electrically insulating polymer material including biological tissue equivalent plastics with radiation. As a result, it was found that the change of the radiation intensity, the dose of radiation, and the change of the output current value uniquely correspond to each other and have a linear linearity. 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 polymer chain-like bonds by radiation mainly near or inside the polymer surface, and carriers such as electrons are generated from the dangling bonds. It is conceivable that an external current is obtained by drifting in an external electric field. It is similar to the internal photoelectric effect when viewed only from the phenomenon that the current value changes due to irradiation of radiation, but it has been confirmed that the current value also changes due to irradiation of β rays (not electromagnetic waves). Are considered different. In other words, in the case of a normal polymer material, electrons, which are particles that carry charge, are in a bound state where they cannot move from the atoms that constitute the molecule, and do not have enough energy to break the binding in the visible light region of 380 nm to 780 nm. So no current flows. It is considered that carriers are induced by or near the surface irradiated with radiation. The radiation in the present invention is ionizing radiation and targets γ rays, β rays, α rays, and X rays.

In the present invention, it is preferable that the polymer material is set to an inter-electrode distance at which an electric resistance value between the electrodes is about 10 ¹⁰ Ω or more, more preferably 10 ¹² Ω or more. When the dose is to be measured, it is desirable to use a 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 radiation absorbed can be measured with a composition equivalent to or similar to that of a living body, and the amount of radiation absorbed into the human body can be further accurately measured.

  Furthermore, in the present invention, the electrically insulating polymer substrate is preferably composed of a biological tissue equivalent plastic when being attached to the body surface or inserted into the body.

  Further, 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 about 90% in effective energy of the irradiated radiation. It is desirable that it is made of an electrically insulating polymer material having the above permeability, and is applied to a patient after being processed into a sheet shape, for example.

  In the present invention, when used for a window of a space for handling radiation, the electrically insulating polymer substrate is preferably made of an electrically insulating polymer material having transparency to visible light.

  The radiation dose measuring device according to the present invention is characterized in that a radiation dose measuring element having at least a pair of electrodes on the surface or inside of an electrically insulating polymer substrate, and a pair of electrodes of the radiation dose measuring element. A voltage applying means for applying a voltage to the electrode, a current detecting means for detecting a current flowing between the electrodes, a dose acquiring means for converting a dose from the detected interelectrode current, and a display means for displaying the dose. The radiation dose is measured using the fact that the output current value of the dosimetry element changes with linear uniqueness with respect to the radiation dose due to radiation irradiation.

  According to such a configuration, when the electrically insulating polymer substrate of the radiation dosimetry element receives radiation in a state where a voltage is applied to the pair of electrodes by the voltage applying means, the surface of the electrically insulating polymer substrate In addition, carriers are generated in the vicinity of the surface, and the generated carriers flow to the positive and negative electrodes. Therefore, radiation can be detected by detecting a weak current due to 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.

  And in this invention, while attaching the said dosimetry element in the front-end | tip of a catheter, it connects to fixed characteristic impedance lines, such as a microstrip line arrange | positioned in the tube of a catheter, and a voltage application means and an electric current detection means It is good also as a structure which has a dose conversion means which converts a dose from the current between electrodes detected by this, and a display means which displays a dose.

  Further, in the present invention, in the button-shaped small housing, the dose measuring element, an electronic processing board having a dose conversion function with a built-in current amplifier and a storage unit for storing measurement data, and a small size A 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. Also good.

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

According to the present invention,
1) Since the radiation dose measuring element can be formed into any shape such as a curved surface or a spherical shape, it can be applied to the human body or organ in radiation therapy to measure the absorbed dose in the body, or the radiation dose due to irradiation with diagnostic X-rays. Can be measured. 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 a radiation control area or 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 can be performed even in a high-intensity radiation environment.
5) Even in a wide voltage range (low voltage of 10 V or less is possible), it is possible to detect a large signal current with a small dark current and measure a radiation dose.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a radiation dose measuring element 1 and a radiation dose measuring apparatus 2 using the same using an electrically insulating polymer material according to the present invention 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 apparatus 2 of the present embodiment includes a radiation dose measuring element 1 for detecting a radiation dose, an apparatus main body 3 for controlling the radiation dose measuring element 1 and calculating a radiation dose, and radiation. And a display device 4 for displaying the measurement result of the dose. In addition, in this embodiment, a dose shows the dose corresponding to the absorbed dose of substances including a biological tissue.

  First, the radiation dose measuring element 1 will be described. As a result of earnest research on the problems described above, the inventors of the present application have found that an electric current flows by irradiating the surface of an electrically insulating polymer substrate composed only of an electrically insulating polymer material, Moreover, it was found that the output current value has linear uniqueness with respect to the dose of irradiated radiation. Radiation irradiated by detecting a change in the current value generated in the electrically insulating polymer substrate or the voltage between electrodes caused by the current by utilizing the linear relationship between the current value and the radiation dose. The present invention has been conceived in which the dose rate can be measured.

  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 the same properties, and has a polymer substrate 11 having electrical insulation at room temperature, It is comprised from a pair of electrodes 12 and 12 provided on the surface of the insulating polymer substrate 11. The electrodes 12 and 12 need not be limited to a pair, and may be formed on the lower surface side to form two pairs of electrodes 12 and 12, for example.

  The electrically insulative polymer substrate 11 is for generating carriers on the surface, in the vicinity of the surface thereof, in the interior thereof, or both by irradiation, and for causing a change in conductance. Various polymer materials including tissue equivalent plastics are used. Can be molded. The electrically insulating polymer substrate 11 is excellent in electrical insulation when not irradiated with radiation, while a minute current flows when irradiated with radiation, and the current value has a linearity proportional to the radiation dose. Have.

In the present embodiment, the electrical insulating polymer substrate 11 has an electrical resistance value between a pair of electrodes of about 10 ¹⁰ Ω or more, more preferably about 10 ¹² Ω, in order to detect a signal of a practical size due to radiation irradiation. The distance between the electrodes is set as described above. In addition, the resistivity of the electrically insulating substance is generally about 10 ¹⁰ Ωcm or more, but the resistivity of the polymer material used for the electrically insulating polymer substrate 11 is a signal detection by radiation irradiation. Is preferably about 10 ¹² Ωcm or more, more preferably about 10 ¹⁴ Ωcm or more. For example, volume resistivity at about room temperature is 10 ¹⁶ Ωcm or more for polyethylene, polypropylene, polyimide, polycarbonate, etc., 10 ¹¹ to 10 ¹² Ωcm for phenol resin, 10 ¹⁵ to 10 ¹⁷ Ωcm for epoxy resin, and polyester resin About 10 ¹⁴ Ωcm.

  Here, the tissue equivalent plastic is an electrically insulating polymer material (plastic) having a chemical formula (or mixing ratio) close to the composition of elements (C, H, O, N, F, etc.) constituting the living tissue. Since the chemical composition is similar, it can be regarded as equivalent to a living tissue in considering the interaction with radiation. The composition of the tissue-equivalent plastic is similar to the elemental composition of living soft tissue and muscle tissue, and for a radiation particle having high energy, a physical quantity representing an amount of energy imparted as a stopping power shows an equivalent value. 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 the tissue equivalent plastic has properties as a plastic, it can be formed into an arbitrary shape and can easily cope with a curved surface shape or a complicated shape.

  Next, the pair of electrodes 12 and 12 is composed of a positive electrode and a negative electrode, and is provided on the surface of the electrically insulating polymer substrate 11 at a predetermined interval as shown in FIG. . 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 a vacuum deposition method. 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, and 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 this 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. An amplifying circuit 33 for amplifying the weak current detected by the current detector 32, a display driving circuit 34 for displaying the display device 4, the current detector 32, the amplifying circuit 33, the display driving circuit 34, and an interface 35. And a microcomputer 36 connected thereto.

  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, the bias voltage to be applied is adjusted by being connected to the microcomputer 36 via the interface 35. 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, a DC voltage of about 1 to 100V. Is set to

  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, it is comprised from the solenoid coil and Hall element which are not shown in figure, and the Hall element has detected the magnetic force line which generate | occur | produced in the solenoid coil by the weak electric 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.

  The microcomputer 36 has a ROM (Read Only Memory), a RAM (Random Access Memory), and a CPU (Central Processing Unit) (not shown), and functions as various control means including a dose conversion means. 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 radiation dose from the detected current value. The conversion formula or conversion table is obtained for each dose measuring 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 weak current value detected by the current detector 32 is stored in the RAM while being updated at a predetermined time interval (for example, 1 second). The CPU acquires the latest current value data stored in the RAM based on the dose measurement program stored in the ROM, and acquires the radiation dose 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 the 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. Also, for example, when a model of a predetermined part of a human body (such as an organ) is formed of tissue equivalent plastic, and electrodes 12 and 12 are formed on the surface of the model, the dose of radiation irradiated to that part is monitored. The radiation dose measuring element 1 is configured.

  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. Thereby, a substantially constant weak current flows from the positive electrode to the negative electrode through the electrically insulating polymer substrate 11. The current detector 32 always 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 sequentially acquired by the CPU, and its increase / 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, carriers are generated near the surface of the electrically insulating polymer substrate 11. appear. As a result, the generated carriers are caused to flow to the electrodes 12 and 12 by the bias 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 CPU calculates the dose of radiation incident on the electrically insulating polymer substrate 11 based on the current increase and the predetermined conversion formula or conversion table described above. The calculated radiation dose is displayed on the display device 4 in the form of a numerical value and a graph.

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 an insulating substrate before applying the electrically insulating polymer substrate 11 to the dosimetry element 1, and A basic experiment was conducted in which a titanium oxide thin film layer, an alumina thin film layer, and a zirconium oxide thin film layer were formed on a substrate and irradiated with radiation, and the result that the output current had a linear uniqueness with respect to the radiation dose was obtained. As disclosed in Japanese Patent Application No. 2004-151087, in this case, it is not necessary to form the metal oxide thin film by a further experiment, and by using the substrate 11 made of only an electrically insulating polymer material. The experimental result that the output current has linear uniqueness with respect to the radiation dose was obtained. Hereinafter, each experimental example will be described.

"Experiment 1"
An experimental example according to the present invention will be described. FIG. 3 is a schematic diagram of a measurement circuit of the radiation detection element 1 (also a radiation dose measurement element) 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 provided on the electrically insulating polymer substrate 11 so as to face each other at an interval. 12. The film 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.

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) (USA) DuPont) was used. Plastic Water (registered trademark) has a specific gravity of 1.039 (g / cm ³ ) and a specific gravity very close to that of water. The composition ratio is 0.599 for carbon C, 0.235 for oxygen O, hydrogen H is 0.078, nitrogen N is 0.018, calcium Ca is 0.068, and chlorine Cl is 0.002. The polyimide is a wholly aromatic polyimide and uses TI-3000 (manufactured by Toray Industries), the specific gravity is about 1.4 (g / cm ³ ), and the composition ratio is 0.525 for carbon C, 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, a DC power supply with a built-in electrometer having an output of 0 to 100 V was used as the experimental power supply, and the current output was measured with a galvanometer (electrometer) G.

  In Experimental Example 1, first, an experiment of irradiating X-rays was performed. As the X-ray irradiation apparatus, Stabilpan II (manufactured by Siemens) was used, and the irradiation conditions were tube voltage 100 kV, effective voltage 57 keV, tube current 20 mA, irradiation time 60 sec, and irradiation distance 40 to 110 cm. The applied voltage was fixed at 10V.

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 represents the X-ray irradiation dose rate, and the vertical axis represents 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 with 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 350 pA was output at an X-ray irradiation dose rate of 35 × 10 ⁻⁴ (C / kg / min). . When the average sensitivity which is the inclination based on the proportional characteristic of this polycarbonate is obtained, it 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. Because it has, there is no problem as a sensor. In particular, it has been confirmed that each electrically insulating polymer material can provide a sufficient output even at a voltage of only 10 V, and that an output current can be obtained even at a voltage of 1 V, and can be used as a sensor even when a low voltage is applied. Is suitable for practical use. Note that the radiation dose and absorbed dose are approximately proportional to the soft tissue of the living body, such as muscles and internal organs. Therefore, the results in the above graph apply equally to the relationship between the generated current value and the absorbed dose. It can be said that it has proportional linearity.

"Experiment 2"
Next, as Experimental Example 2, the characteristics of the output current value with respect to the irradiation dose rate when γ rays were irradiated among the radiation were examined. The dimensions of the radiation dose measuring element 1 and the type of the electrically insulating polymer material are the same as in Experimental Example 1. The γ-ray irradiation device is a 60Co γ-ray source using a Toshiba Cobalt 60 rotation therapy device (manufactured by Toshiba). The irradiation conditions are γ-ray energy average 1.25 MeV, irradiation time 60 sec, irradiation distance 65-65. It was 125 cm. The applied voltage is 10V.

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. As in the case of the X-ray in Experimental Example 1, the current value generated in the substrate 11 by various electrically insulating polymer materials can be uniquely determined by showing a proportional relationship with the irradiation dose rate of γ-rays. Recognize. Further, when the output current value of polycarbonate, Teflon (registered trademark) and PEEK (registered trademark) is an X-ray irradiation dose rate of approximately 9 × 10 ⁻⁴ (C / kg / min), a current value of approximately 35 pA to 40 pA is obtained. In contrast to polyimide, polyimide had a current value of about 8 pA and Plastic Water (registered trademark) had a current value of about 14 pA for the same radiation dose rate. However, since any electrically insulating polymer material outputs a current value that can be sufficiently measured by an applied voltage of about 10 V, all of them are practical as a sensor. The average sensitivity of the polycarbonate was about 30 [nA / (C / kg / min)].

"Experiment 3"
Next, an experiment was conducted to determine whether or not the electrically insulating polymer substrate 11 has a linearity in which the output current value is proportional to the radiation dose even in a vacuum atmosphere. This is because the proportional characteristics of the irradiation dose and the current value in the experimental example 1 and the experimental example 2 are affected by the influence of the surrounding atmosphere, for example, the ionization of the gas existing in the vicinity of the electrically insulating polymer substrate 11. It is an experiment to confirm whether there is any. Polycarbonate showing the highest current output was used as the material of the electrically insulating polymer substrate 11, and X-rays were irradiated under the same conditions as in Experimental Example 1 except for the conditions in a vacuum atmosphere. The degree of vacuum was set to 10 ⁻³ Torr order.

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 is recognized that the output current value has a proportional linearity with respect to the radiation dose rate even in a vacuum atmosphere. In addition, when the output current value is an X-ray irradiation dose rate (dose rate on the vacuum chamber surface) of about 20 × 10 ⁻⁴ (C / kg / min), it is about 13 pA and the result in the atmosphere (about 230 pA) It is decreasing more. This is considered because the radiation dose reaching the dose measuring element 1 is attenuated by setting the radiation dose measuring element 1 in the vacuum chamber.

“Experiment 4”
Next, the response characteristic of the external output current with respect to ON / OFF of the X-ray was examined. The electrically insulating polymer material uses polycarbonate, and the X-ray irradiation time is 60 seconds. The externally applied voltage is constant at 10 V, and the X-ray intensity is 8 × 10 ⁻⁴ (C / kg / min), 9 × 10 ⁻⁴ (C / kg / min), 11 × 10 ⁻⁴ (C / kg / min) and 13 × 10 ⁻⁴ (C / kg / min) in order, and the output current value at that time was measured.

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, when the X-ray intensity is 8 × 10 ⁻⁴ (C / kg / min), an output current value of about 115 pA is shown, and when the X-ray intensity is 9 × 10 ⁻⁴ (C / kg / min), about 130 pA, It can be seen that the current value is about 155 pA at 11 × 10 ⁻⁴ (C / kg / min) and about 185 pA at 13 × 10 ⁻⁴ (C / kg / min). It can be seen that increasing the X-ray intensity in this way increases the amount of charge carriers generated in the electrically insulating polymer substrate 11 and increases the output current. Moreover, it turns out that the response speed with respect to ON / OFF of an X-ray source is less than 1 second.

  Next, an embodiment using the radiation detection element 1 having another configuration 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. Using the radiation detection element 1 in which 12 and 12 are inserted into the electrically insulating polymer substrate 11, an experiment was conducted as to whether similar effects could be obtained.

"Experiment 5"
In this Experimental Example 5, an experiment was conducted to confirm whether or not a practical current is output even when the pair of electrodes 12 and 12 are inserted not inside the surface but inside. 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 1 mm thick portion into a 10 mm × 10 mm × 1 mm size radiation detection element 1. The distance between the electrodes 12, 12 is 6 mm. An experiment was performed by applying a voltage of 1 to 100 V to the electrodes 12 and 12. The X-ray irradiation dose was kept constant at 35 × 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, in a state where the number of charged particles generated in the radiation detection element 1 is considered to be constant at a constant radiation dose, the charged particle velocity v increases by increasing the applied voltage from 1 V to 100 V. It can be seen that the current increases according to the relational expression of current density i = nev (A / m ² ). Here, n is the density of charged particles, e is the charge amount of charged particles, v is the speed of charged particles, and v = μ (V / d). Where μ is the mobility of charged particles. Therefore, 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 dose measuring element 1 can be obtained in the same manner as the structure on the surface.

Experimental Example 6
Next, the response characteristic of the external output current with respect to the X-ray ON / OFF was examined 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 × 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. FIG. 10 shows that the radiation detection element 1 generates a constant and stable output current with respect to the irradiation time. Accordingly, it is considered that a stable signal is guaranteed even for a long-time measurement. In FIG. 10, spike-like signals are seen at 1 minute and 5 minutes, which are electrical noises generated from the X-ray generator when X-ray irradiation is turned on / off.

  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 dose. Was found to have a proportional relationship. Further, based on the result of the above experimental example, if the phenomenon described above is mainly due to 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 result can be obtained even when the dose measuring element 1 is irradiated with β 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.

"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 amount with respect to the irradiation depth when 1.25 MeV of Co60 (γ-rays) is used as a condition. FIG. 13 shows the case where 200 keV photons corresponding to X-ray irradiation are used as a condition. The energy accumulation amount with respect to the irradiation depth is shown.

  Referring to FIG. 12, Co60, which is γ-ray, is saturated at 3 to 4 mm. Therefore, when applied to the electrically insulating polymer substrate 11, it is preferable that the thickness be equal to or greater than the saturation depth. On the other hand, as shown in FIG. 13, when a 200 KeV photon assuming X-rays is irradiated, it is saturated at 0.1 mm or more.

  In consideration of the above results, the electrically insulating polymer substrate 11 having a thickness of 3 to 4 mm or more is preferable when measuring the dose of γ-ray, and 0 when measuring the dose of X-ray. An electrically insulating polymer substrate 11 having a thickness of 1 mm or more is preferable. In order to make use of the workability of the polymer material, the thinner one is preferable. In this embodiment, the electrically insulating polymer substrate 11 having a thickness of 1 mm is used for the experiment.

In addition, when the electrical resistance between the electrodes was measured for the electrically insulating polymer substrate 11 used in this experimental example, all were 5 × 10 ¹² Ω or more.

According to the present embodiment as described above, the following effects can be obtained.
(1) Electrically insulating polymer materials such as tissue-equivalent plastics can be formed into any shape such as the human body and organs, so it can be used with 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 suppressed. For example, it is formed into a thin curved surface and directly attached to the human body, etc., and the absorbed dose in the living body is measured while performing radiotherapy, or the dose measuring element 1 is attached to the distal end of the catheter and inserted into the body, The absorbed dose in vivo (in blood) can be measured, and it can be said that the applicability and feasibility are extremely high.
(2) An organ model is made of a 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 irradiation from multiple directions. There is an effect that measurement can be made without direction dependency, such as radiation dose measurement not only on the front side but also on the back side part.
(3) Since electrically insulating polymer materials such as tissue-equivalent plastics are solids, they do not become large devices like tissue-equivalent gases, and can detect the current value and detect radiation dose even at low voltages. Miniaturization can be achieved. In addition, there are effects such as measurement with excellent operational stability, reliability, and durability even under a high-intensity radiation environment.
(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 10 V or less.
(5) It is also possible to measure the radiation dose in a radiation control area or general environment with a tissue model that simulates the human body.

  The radiation dose measuring element 1 and the radiation dose measuring device 2 using the same according to the present invention are not limited to the above-described embodiments, and can be appropriately changed.

  For example, you may provide the alarm device which alert | reports that the radiation beyond a predetermined value was 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.

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

“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 exposure dose by X-ray imaging is measured. is there.

  In the first embodiment, the electrically insulating polymer substrate 11 is processed into a sheet shape with an electrically insulating polymer material having a permeability of about 90% or more of the effective energy of the radiation to be irradiated. The electrically insulating polymer substrate 11 has a thickness of about 100 μm to 1 mm, and preferably has a flexibility that can be easily deformed and has a size of 10 cm × 10 cm or more. For example, polyethylene is processed into a sheet shape, a pair of electrodes 12 and 12 are embedded at both ends thereof, and dose measurement is performed by connecting to the apparatus body 3 via coaxial cables 41 and 41 which are a pair of constant characteristic impedance wires. The apparatus 2 is configured. The apparatus main body 3 has a voltage application control function, a current detection / display function, a current-dose rate conversion function, and a data storage / recording function. Then, by applying a predetermined voltage between the electrodes 12 and 12 by the apparatus body 3 and monitoring the current value and converting it to the exposure dose, it is possible to manage the whole body exposure dose of the patient P in real time. Alternatively, the electrically insulating polymer substrate 11 may be placed only on a specific part such as a genital organ of a patient to manage the exposure dose for each organ.

  When used in the form of Example 1, the characteristics required for determining the material and size of the substrate 11 are to maintain the quality of the transmitted image in addition to the electrical insulation and flexibility. Therefore, it is desirable to select a material and a thickness that can ensure 90% or more transparency in the effective energy of the X-ray generator.

  Furthermore, although not shown in the figure, the window surface of a clean bench or a glove box 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.

“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, 12 are embedded in the substrate 11, and the pair of electrodes 12, 12 are attached to the catheter 50. Dose measurement is performed by connecting to a pair of microstrip lines 52 and 52 disposed in the tube 51, connecting the pair of microstrip lines 52 and 52 to a pair of coaxial cables 41 and 41, and connecting to the apparatus body 3. The apparatus 2 is configured. Similar to the first embodiment, the apparatus main body 3 has a voltage application control function, a current detection / display function, a current-dose rate conversion function, and a data storage / recording function.

  By applying a predetermined voltage by the apparatus main body 3 and monitoring the current value 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 exposure dose of each organ at the distal end of the catheter during an interventional radiology (IVR) procedure.

“Example 3”
Next, Example 3 of the present embodiment will be described. In the 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, and the radiation measurement is performed in real time for the worker who handles radiation. It is an example that makes possible.

  As shown in FIG. 16, the dose measuring apparatus 2 according to the third embodiment has a disk shape in which a pair of electrodes 12 and 12 are embedded in a cylindrical tubular casing 60 having a diameter of about 20 mm and a thickness of about 10 mm. The electrically insulating polymer substrate 11, the electronic circuit substrate 61, a small battery 62 made up of a button battery, a coin battery or the like, 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, and a disk-shaped electrically insulating polymer substrate 11; The small battery 62 and the measurement data storage electronic circuit element 66 are connected via microstrip lines 52 and 52 which are a pair of specific impedance lines.

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

  Further, by setting a dose threshold value in 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 integrated dose exceeds the threshold value, the operator is notified in real time. An exposure warning can be issued. 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 these in combination is conceivable. The threshold value can be changed by the exposure dose management device 67. In addition, the disk-shaped dose measuring element 1 of Example 3 is an example, and may be formed in a cross-sectional square shape, a cross-sectional hexagonal shape, or the like.

Example 4
Next, Example 4 of the present embodiment will be described. In the fourth embodiment, the dose measuring element 1 is incorporated in the shoe sole 71 of the shoe 70 so as to measure the exposure dose of the shoe sole 71, and radiation damage is diffused by the radiation material adhering to the shoe sole of the worker. This is an example that can prevent this.

  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 substrate 61 and a small battery 62 are embedded in a heel portion of a shoe 70. And the alarm device 63 is built in, and a dose measuring device is comprised. 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, and the electrically insulating polymer substrate 11, the CPU 65 and the small battery 62. Connection is made via a pair of coaxial cables 41, 41.

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

  As described above, the dose measuring element 1 and the dose measuring device 2 of the present embodiment are not limited to the above-described examples, and can be applied to various modes affected by radiation.

It is a schematic diagram which shows one Embodiment of the radiation dose measuring apparatus which concerns on this invention. It is a block diagram which shows the apparatus main body of this embodiment. It is a schematic diagram of the radiation detection element in Experimental Example 1. 6 is a graph showing a relationship between an X-ray irradiation dose rate (horizontal axis) and an output current value (vertical axis) in Experimental Example 1. 6 is a graph showing a relationship between a γ-ray irradiation dose rate (horizontal axis) and an output current value (vertical axis) in Experimental Example 2. It is a graph which shows the relationship between the X-ray irradiation dose rate (horizontal axis) in the vacuum chamber surface in the vacuum atmosphere in Experimental example 3, and an output electric current value (vertical axis). It is a graph of the response characteristic which shows the relationship between the X-ray irradiation time (horizontal axis) and output current value (vertical axis) in Experimental Example 4. It is a schematic diagram which shows the Example using the radiation detection element which consists of another structure. It is a graph which shows the relationship between the voltage between electrodes (horizontal axis) and the output current value (vertical axis) in Experimental Example 5. It is a graph which shows the relationship between the X-ray irradiation time (horizontal axis) and the output current value (vertical axis) in Experimental Example 6. It is a figure which shows the shape variation of the radiation dose measuring element which concerns on this invention. It is a graph which shows the relationship between the irradiation depth (horizontal axis) of Co60 and energy accumulation (vertical axis) in Experimental Example 7. It is a graph which shows the relationship between the irradiation depth (horizontal axis) of 200 KeV photon in Experimental example 7, and energy storage (vertical axis). It is a schematic diagram which shows Example 1 which applied the dosimetry apparatus based on this invention to the sheet form. It is a schematic diagram which shows Example 2 which applied the dosimetry apparatus based on this invention to the catheter. It is a schematic diagram which shows Example 3 which applied the dosimetry apparatus based on this invention in the button-shaped housing | casing. It is a schematic diagram which shows Example 4 which applied the dosimetry apparatus based on this invention to shoes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiation dose measuring element 2 Radiation dose measuring device 3 Apparatus main body 4 Display apparatus 11 Electrical insulating polymer substrate 12 Electrode 31 Voltage application circuit 32 Current detector 33 Amplifying circuit 34 Display drive circuit 35 Interface 36 Microcomputer 41 Coaxial cable DESCRIPTION OF SYMBOLS 50 Catheter 51 Catheter tube 52 Microstrip line 60 Button-shaped housing 61 Electronic circuit board 62 Small battery 63 Alarm device 64 External connection connector 65 CPU
66 Measurement data storage electronic circuit element 67 Dose management device 70 Shoes 71 Shoes sole

[0005]
There is also a merit that
[0016]
Therefore, the radiation dosimetry element using the electrically insulating polymer material according to the present invention is characterized by a substrate composed of a polymer material having electrical insulation properties at room temperature and the surface of the electrically insulating polymer substrate. Or having at least a pair of electrodes provided inside, and collecting electrons and holes generated in the electrically insulating polymer substrate upon irradiation of radiation to the electrodes and detecting them as current. .
[0017]
In the present invention, the electrically insulating polymer substrate has an output current value that is linearly unique with respect to the radiation dose when irradiated with radiation.
[0018]
Here, the mechanism of the present invention will be described. A phenomenon in which a photovoltaic effect of an insulator or semiconductor irradiated with light occurs 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 the current value of the polymer material irradiated with radiation is also an external signal by irradiating the electrically insulating polymer material including biological tissue equivalent plastics with radiation. As a result, it was found that the change of the radiation intensity, the dose of radiation, and the change of the output current value uniquely correspond to each other and have a linear linearity. 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 polymer chain-like bonds by radiation mainly near or inside the polymer surface, and carriers such as electrons are generated from the dangling bonds. It is conceivable that an external current is obtained by drifting in an external electric field. It is similar to the internal photoelectric effect when viewed only from the phenomenon that the current value changes due to irradiation of radiation, but it has been confirmed that the current value also changes due to irradiation of β rays (not electromagnetic waves). Are considered different. In other words, in the case of a normal polymer material, electrons, which are particles that carry charge, are in a bound state where they cannot move from the atoms constituting the molecule, and do not have enough energy to break the binding in the visible light region of 380 nm to 780 nm. So no current flows. It is considered that carriers are induced by or near the surface irradiated with radiation. The radiation in the present invention is ionizing radiation and targets γ rays, β rays, α rays, and X rays.
[0019]
In the present invention, the polymer material is preferably set to an interelectrode distance at which an electrical resistance value between the electrodes is about 10 ¹⁰ Ω or more, more preferably 10 ¹² Ω or more.

Claims (11)

  An electrically insulating polymer material 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 used.   2. The radiation dose measurement according to claim 1, wherein the electrically insulating polymer substrate has an output current value linearly unique with respect to the radiation dose due to radiation irradiation. element. 3. The radiation dose measurement according to claim 1, wherein the electrically insulating polymer substrate is configured to have an interelectrode distance in which an electrical resistance value between the electrodes is about 10 ¹⁰ Ω or more. element. 3. The radiation dose measurement according to claim 1, wherein 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. element.   3. The radiation dose measurement according to claim 1, wherein the electrically insulating polymer substrate is made of a biological tissue equivalent plastic and is affixed to or inserted into a body surface. element.   In claim 1 or claim 2, when used for measurement of exposure dose at the time of transmission imaging by radiation irradiation, radiation irradiation treatment or the like, the electrically insulating polymer substrate is approximately reduced in effective energy of the irradiated radiation. A radiation dose measuring element comprising an electrically insulating polymer material having a transmittance of 90% or more.   3. The method according to claim 1, wherein the electrically insulating polymer substrate is made of an electrically insulating polymer material having transparency with respect to visible light when used for a window of a space that handles radiation. Radiation dosimetry element. A radiation dosimetry element according to any one of claims 1 to 7,
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.   A dose measuring element according to any one of claims 1 to 4 is attached to the distal end of the catheter, and connected to a certain characteristic impedance line arranged in the tube of the catheter, and a voltage applying means and a current detecting means A radiation dose measuring apparatus comprising: a dose conversion means for converting a dose from an interelectrode current detected by the connection, and a display means for displaying the dose.   An electronic device comprising a dose measuring element according to any one of claims 1 to 4, an arithmetic 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 circuit 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. Radiation dosimetry apparatus characterized by being made.   An electronic circuit board comprising a dose measuring element according to any one of claims 1 to 4, an arithmetic processing unit having a dose conversion function with a built-in current amplifier, and a storage unit for storing measurement data in a bottom portion of a shoe And a small battery, an alarm device, and an external connection connector, 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 dosimetry apparatus characterized by that.

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