WO2006104046A1 - Élément de mesure de dose de radiation et dispositif de mesure de dose de radiation utilisant un matériau polymère isolant électrique - Google Patents

Élément de mesure de dose de radiation et dispositif de mesure de dose de radiation utilisant un matériau polymère isolant électrique Download PDF

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Publication number
WO2006104046A1
WO2006104046A1 PCT/JP2006/305986 JP2006305986W WO2006104046A1 WO 2006104046 A1 WO2006104046 A1 WO 2006104046A1 JP 2006305986 W JP2006305986 W JP 2006305986W WO 2006104046 A1 WO2006104046 A1 WO 2006104046A1
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Prior art keywords
radiation
dose
electrically insulating
insulating polymer
measuring element
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PCT/JP2006/305986
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English (en)
Japanese (ja)
Inventor
Mitsuo Shimozuma
Hiroyuki Date
Josuke Nakata
Hidemasa Tomozawa
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National University Corporation Hokkaido University
Kyosemi Corporation
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Application filed by National University Corporation Hokkaido University, Kyosemi Corporation filed Critical National University Corporation Hokkaido University
Priority to JP2007510455A priority Critical patent/JPWO2006104046A1/ja
Publication of WO2006104046A1 publication Critical patent/WO2006104046A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/02—Dosimeters

Definitions

  • 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.
  • 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.
  • 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.
  • Patent Document 2 proposes a radiation detection apparatus using an ionization chamber.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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
  • 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.
  • the absorbed dose represents the amount of energy absorbed per unit mass of the substance. Therefore, the amount depends on the type of substance.
  • 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.
  • 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.
  • the output current value when irradiated with radiation overlaps with the dark current or is lower than the dark current.
  • the resistance ratio (radiation OFFZ radiation ON) is 1.0 or less in the range where the applied voltage is 4V or more.
  • 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.
  • the present invention has been made to solve such problems, and has an object to obtain at least one of the following operational effects.
  • 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.
  • the radiation dose can be measured in real time.
  • An object of the present invention is to provide a radiation dosimetry element and a radiation dosimetry device using an electrically insulating polymer material.
  • 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.
  • a dosimetry device equipped with these electrodes and are proposing that it can solve the conventional problems.
  • 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.
  • 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.
  • 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.
  • the electrically insulating polymer substrate has an output current value linearly unique with respect to the radiation dose by irradiation of radiation.
  • 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.
  • 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.
  • the external current can be obtained by drifting in the external electric field.
  • the current value changes due to the irradiation of radiation, it is confirmed that the current value also changes by irradiation of force ⁇ -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.
  • force ⁇ -rays not electromagnetic waves
  • the radiation in the present invention is ionizing radiation and targets ⁇ rays, j8 rays, ⁇ rays, and X rays.
  • the polymer material is set to an inter-electrode distance at which an electrical resistance value between the electrodes is about 10 ⁇ or more, more preferably 10 12 ⁇ or more.
  • an electrical resistance value between the electrodes is about 10 ⁇ or more, more preferably 10 12 ⁇ or more.
  • 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.
  • 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.
  • the electrically insulating polymer substrate when used for measuring the exposure dose of a patient at the time of imaging by radiation irradiation or radiation irradiation treatment, 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.
  • the electrically insulating polymer substrate when used in a window of a space that handles radiation, is constituted by an electrically insulating polymer material having transparency to visible light. Is preferred.
  • the radiation dosimetry apparatus 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.
  • 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.
  • 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.
  • 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.
  • 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 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.
  • 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.
  • 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.
  • the dose indicates a dose corresponding to the absorbed dose of a substance such as a living tissue.
  • the radiation dose measuring element 1 will be described.
  • 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.
  • the output current value has a linear uniqueness with respect to the dose of irradiated radiation.
  • 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.
  • 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.
  • the electrodes 12 and 12 may be formed on the lower surface side to form two pairs of electrodes 12 and 12.
  • 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.
  • 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 (> ⁇ 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 ⁇ or more, and the resistivity of the electrically insulating material is generally about 10 1 (> ⁇ cm or more).
  • the resistivity of the polymer material used for the substrate 11 is more preferably about 10 14 ⁇ cm or more, preferably about 10 12 Qcm or more, if signal detection by irradiation is possible.
  • volume resistivity at around room temperature is 10 16 ⁇ cm or more for polyethylene, polypropylene, polyimide, polycarbonate, etc., and 10 15 to 10 17 ⁇ for IOU IO Q CH ⁇ epoxy resin for phenol resin. cm, about 10 14 ⁇ cm for polyester resin.
  • 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.
  • the tissue equivalent plastic include polycarbonate, acrylic resin, polyethylene, polyamide nylon, polyethylene terephthalate, water equivalent plastic, urethane resin, epoxy resin, polytetrafluoroethylene, and the like.
  • tissue equivalent plastics have properties as plastics, they can be formed into any shape and can easily cope with curved or complex shapes.
  • 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.
  • 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.
  • 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.
  • the current detector 32 is connected to the positive electrode 12 of the radiation dose measuring element 1.
  • 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.
  • an inexpensive current operational amplifier may be used as the current detector 32.
  • 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.
  • ROM Read Only Memory
  • RAM Random Access Memory
  • CPU Central Processing Unit
  • various control means including a dose conversion means Function as.
  • 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.
  • 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
  • a predetermined bias voltage is applied to the pair of electrodes 12 and 12 by the voltage application circuit 31.
  • 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.
  • the CPU detects a small current increase due to radiation irradiation, the current increase and the above-mentioned conversion formula ⁇ 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.
  • 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.
  • 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
  • Plastic Water 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
  • nitrogen N is 0.05.
  • the specific gravity of polycarbonate is about 1.2 (g / cm 3 ).
  • 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.
  • 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.
  • 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.
  • 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)].
  • PEEK registered trademark
  • plastic water registered trademark
  • 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.
  • 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.
  • gamma ray irradiation apparatus is gamma ray source 60Co using Toshiba Cobalt 60 rotation therapy apparatus (manufactured by Toshiba), irradiation conditions, average ⁇ 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 ⁇ 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 ⁇ -rays.
  • 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.
  • 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)].
  • FIG. 6 is a graph showing the results of Experimental Example 3.
  • the horizontal axis is the radiation dose rate
  • 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.
  • 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.
  • 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.
  • 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).
  • 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.
  • FIG. 1 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.
  • 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.
  • 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
  • the vertical axis represents the output current value.
  • 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.
  • 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.
  • 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.
  • 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 ⁇ 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.
  • 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 ( ⁇ -ray) irradiation
  • 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.
  • Co60 which is a ⁇ -ray
  • Co60 which is a ⁇ -ray
  • the thickness 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.
  • 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! /.
  • the electrically insulating polymer substrate 11 having a thickness of 3 to 4 mm or more preferably measures the dose of X rays.
  • the electrically insulating polymer substrate 11 having a thickness of 0.1 mm or more is preferable.
  • an electrically insulating polymer substrate 11 having a thickness of lmm is used in the experiment.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the dosimetry apparatus 2 is configured with this.
  • 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.
  • 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.
  • IVR interventional radiology
  • Example 3 Next, Example 3 of the present embodiment will be described.
  • 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.
  • 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.
  • 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.
  • 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.
  • the worker can be controlled.
  • a warning of exposure can be issued in real time.
  • 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.
  • 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.
  • Example 4 of the present embodiment will be described.
  • 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.
  • 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.
  • 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.
  • 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.
  • the alarm device 63 is preferably a sound generator such as a buzzer.
  • 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.
  • 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.
  • FIG.5 Shows the relationship between ⁇ -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.
  • FIG. 8 is a schematic diagram showing an embodiment using a radiation detection element having another configuration.
  • 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.
  • 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.
  • 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.

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Abstract

L’invention concerne un élément de mesure de dose de radiation et un dispositif de mesure de dose de radiation qui utilisent un matériau polymère isolant vis-à-vis de l’électricité, excellent en matière de traitement, mesurant la dose d’un matériau maintenu très près d’un tissu corporel et susceptible de détecter un courant de signal important sur une tension plus vaste (par exemple, un faible courant sous-jacent à une faible tension allant jusqu’à 10V). L’élément de mesure comprend un substrat (11) fait d’un matériau polymère ayant une propriété isolante vis-à-vis de l’électricité à la température ambiante, et au moins une paire d’électrodes (12, 12) installées à la surface ou à l’intérieur de ce substrat polymère isolant vis-à-vis de l’électricité (11). En cas d’application d’une radiation au substrat (11), on obtient une valeur de courant de sortie linéaire et unique à la fréquence de dose de la radiation.
PCT/JP2006/305986 2005-03-25 2006-03-24 Élément de mesure de dose de radiation et dispositif de mesure de dose de radiation utilisant un matériau polymère isolant électrique WO2006104046A1 (fr)

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JP2010172427A (ja) * 2009-01-28 2010-08-12 Japan Health Science Foundation 陽子線治療におけるポジトロン放出核種のアクティビティ分布のシミュレーション方法
WO2011044221A3 (fr) * 2009-10-06 2012-04-26 Massachusetts Institute Of Technology Procédé et appareil pour déterminer un rayonnement
JP2013506850A (ja) * 2009-10-01 2013-02-28 ローマ リンダ ユニヴァーシティ メディカル センター イオン誘起衝突電離検出器及びその使用
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KR20200059008A (ko) * 2018-11-20 2020-05-28 한국원자력연구원 방사선 피조사체의 흡수선량의 측정 방법 및 방사선 피조사체의 흡수선량의 측정 장치
WO2022233826A1 (fr) 2021-05-06 2022-11-10 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif de mesure de dose de radiations reçue par réflectométrie ou transférométrie
US11505467B2 (en) 2017-11-06 2022-11-22 Massachusetts Institute Of Technology High functionalization density graphene

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US9267908B2 (en) 2008-03-04 2016-02-23 Massachusetts Institute Of Technology Devices and methods for determination of species including chemical warfare agents
US8951473B2 (en) 2008-03-04 2015-02-10 Massachusetts Institute Of Technology Devices and methods for determination of species including chemical warfare agents
US9114377B2 (en) 2008-12-12 2015-08-25 Massachusetts Institute Of Technology High charge density structures, including carbon-based nanostructures and applications thereof
US8735313B2 (en) 2008-12-12 2014-05-27 Massachusetts Institute Of Technology High charge density structures, including carbon-based nanostructures and applications thereof
JP2010172427A (ja) * 2009-01-28 2010-08-12 Japan Health Science Foundation 陽子線治療におけるポジトロン放出核種のアクティビティ分布のシミュレーション方法
US8456073B2 (en) 2009-05-29 2013-06-04 Massachusetts Institute Of Technology Field emission devices including nanotubes or other nanoscale articles
JP2013506850A (ja) * 2009-10-01 2013-02-28 ローマ リンダ ユニヴァーシティ メディカル センター イオン誘起衝突電離検出器及びその使用
US9213107B2 (en) 2009-10-01 2015-12-15 Loma Linda University Medical Center Ion induced impact ionization detector and uses thereof
US8426208B2 (en) 2009-10-06 2013-04-23 Massachusetts Institute Of Technology Method and apparatus for determining radiation
WO2011044221A3 (fr) * 2009-10-06 2012-04-26 Massachusetts Institute Of Technology Procédé et appareil pour déterminer un rayonnement
US8187887B2 (en) 2009-10-06 2012-05-29 Massachusetts Institute Of Technology Method and apparatus for determining radiation
US9770709B2 (en) 2010-11-03 2017-09-26 Massachusetts Institute Of Technology Compositions comprising functionalized carbon-based nanostructures and related methods
US8476510B2 (en) 2010-11-03 2013-07-02 Massachusetts Institute Of Technology Compositions comprising and methods for forming functionalized carbon-based nanostructures
JP2015516183A (ja) * 2012-03-08 2015-06-11 ザ・ジョンズ・ホプキンス・ユニバーシティ 放射線治療における機械及び線量測定の品質確度をリアルタイムに測定する方法及び装置
US11505467B2 (en) 2017-11-06 2022-11-22 Massachusetts Institute Of Technology High functionalization density graphene
KR20200059008A (ko) * 2018-11-20 2020-05-28 한국원자력연구원 방사선 피조사체의 흡수선량의 측정 방법 및 방사선 피조사체의 흡수선량의 측정 장치
KR102172729B1 (ko) * 2018-11-20 2020-11-02 한국원자력연구원 방사선 피조사체의 흡수선량의 측정 방법 및 방사선 피조사체의 흡수선량의 측정 장치
WO2022233826A1 (fr) 2021-05-06 2022-11-10 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif de mesure de dose de radiations reçue par réflectométrie ou transférométrie
FR3122740A1 (fr) 2021-05-06 2022-11-11 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif de mesure de dose de radiations reçue par réflectométrie ou transférométrie

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