Method for constructing a radiation protection device to visualize interaction with ionizing radiation

Abstract

The invention relates to a method for making a radiation protection device for visualizing interaction with ionizing radiation, characterized in that it consists of preparing a homogeneous mixture of a resin and at least one scintillator material in powder form, then adding a hardener, mixing homogeneously, and then pouring the mixture thus prepared into a mold to form a homogeneous part. Figure 1

Description

Title of the invention: Method for making a radiation protection device to visualize the interaction with ionizing radiation Scope of the invention

[0001] The present invention relates to the field of prevention against risks arising from exposure to ionizing radiation.

[0002] Ionizing radiation is extremely useful in medicine and industry. For example, medical radiography uses the ability of X-rays to penetrate the human body for imaging bone structure or the vascular network, or for destroying tumor cells by applying high, precisely localized doses. In industry, ionizing radiation is used to destroy microorganisms, fungi, bacteria, and viruses, to sterilize equipment or food, and to treat or analyze materials.

[0003] However, notwithstanding these beneficial effects, ionizing radiation contributes to the ionization of molecules present in living organisms and can produce more or less harmful effects on health in the event of excessive exposure. Researchers have observed the damage and disruptions caused by ionizing radiation to DNA. They are also analyzing the repair mechanisms that a cell is able to activate when its DNA has been damaged.

[0004] High-intensity irradiation by ionizing radiation causes immediate effects on living organisms, such as burns of varying severity. The absorbed dose (in grays) is used to characterize these immediate effects following high-intensity irradiation (accidental or therapeutic for treating cancer). For example, radiation oncologists use the absorbed dose to quantify the energy delivered to the tumors they treat with radiation.

[0005] Exposure to higher or lower doses of ionizing radiation can have long-term effects in the form of cancers and leukemias.

[0006] The potential effect of radiation is quantified by a unit called the Sievert (symbol Sv). This represents the absorption of radiation by the human body and the associated effects. For example, the natural radioactivity to which the average French person is exposed is 2.4 mSv (2.4 millisieverts) per year. For a nuclear worker, the average is 20 mSv per year. The lethal dose is around 8,000 to 10,000 mSv. Measuring devices (Geiger counters) or dosimeters are used to detect radiation and measure the doses received.

[0007] This is why people working in environments using ionizing radiation are subject to strict radiation protection rules, requiring them to maintain as much distance as possible from the radiation source, use personal or fixed shielding, and minimize their radiation exposure. Workers who may be exposed to ionizing radiation during their work (nuclear industries, doctors, radiologists, etc.) wear dosimeters, gloves, belts, and rings that measure the amount of radiation to which they have been exposed.

[0008] These devices make it possible to ensure that the person has not received a dose exceeding the tolerated standard or to measure its location and extent.

[0009] However, dosimeters are expensive equipment, and often provide information only after the fact, not allowing the operator to become immediately aware of an accidental exposure to ionizing radiation that no human sense can perceive directly.

[0010] Two main families of dosimeters are used:

[0011] Passive dosimeters do not provide instantaneous measurement and require a Post-hoc laboratory analysis. These devices are considered the most reliable and are generally used for legal dosimetry. These devices do not allow differentiation between the day or worksite on which the dose was captured and do not provide instantaneous information on the dose rate or the integrated dose.

[0012] Passive dosimeters are used for whole-body dosimetry to estimate the dose taken by the operator, or for extremity dosimetry to estimate more precisely the dose taken by the operator at the level of the fingers or the lens for example.

[0013] Active dosimeters allow for real-time measurement of the dose rate and dosimetry of operators. These devices make it possible to alert the operator in real time and, in particular, to indicate if they risk exceeding the dosimetry threshold for which their operation was planned during the preliminary study phase. State of the art

[0014] French patent FR3051919A1 describes a dosimeter for the detection of ionizing radiation, comprising a polymer matrix made of a radiosensitive material, in which particles capable of producing free radicals when exposed to ionizing radiation are dispersed. The dosimeter is characterized in that said particles are diamond particles having a submicrometer or nanometer size and whose surface has a negative electron affinity. The radiosensitive material may be of the gel type (such as dosimetric gels, including polymerizable gels and radiochromic polymerized gels) or of the type solid polymer (such as solvent-free radiosensitive polymers). The incorporation of nanometer-sized (these particles are also called nanoparticles) or submicrometer-sized diamond particles into a radiosensitive material improves the detection performance of the dosimeter by allowing it to have better sensitivity, while maintaining the tissue equivalence of the dosimeter.

[0015] Patent application EP3374801 describes a device for determining a dose deposited in a scintillator by ionizing radiation, comprising:

[0016] - a scintillator configured to be irradiated by ionizing radiation and suitable for emit scintillation photons when interacting with ionizing radiation;

[0017] - a measuring device comprising a single photodetector, said photodetector being a low-noise photodetector, the determining device being configured such that the photodetector operates in single-photon counting mode, the photodetector providing, at its output, a measure of the total light intensity received by the photodetector from the scintillator; and

[0018] - an analyzer configured to determine a dose deposited in the scintillator by ionizing radiation only from the total light intensity measured by the photodetector and a predetermined constant depending only on the scintillator, the luminous efficiency of the determining device and the type of ionizing radiation.

[0019] US patent application 20120106716A1 describes a method for determining the alignment of a light field and an X-ray field of a radiographic apparatus. The method consists of directing the light field onto an exposure area, positioning a scale and an X-ray indicator element together on the exposure area such that the scale and the X-ray indicator element intersect an edge of the light field. The X-ray indicator element is designed to emit light upon X-ray exposure in such a way that the X-ray exposed areas can be distinguished from the unexposed areas. Disadvantages of prior art

[0020] Prior art solutions are not satisfactory because their manufacturing and usage complexity does not allow them to be used as routine equipment that immediately and intuitively alerts the operator in a context subject to ionizing radiation. Solution provided by the invention

[0021] In its most general sense, the invention relates to a method for making a radiation protection device for visualizing the interaction with ionizing radiation, characterized in that it consists of preparing a homogeneous mixture of a resin and at least one scintillator material in powder form, then add a hardener, mix homogeneously and then pour the mixture thus prepared into a mold to form a homogeneous part.

[0022] Advantageously: - the resin is an epoxy type resin - the scintillator material is of the strontium aluminate type - the scintillator material is of the gadolinium oxysulfide type doped with terbium (Gd2O2S: Tb) - it includes an additional step of embedding a radiopaque, comb-shaped structure in the mold - said radio-opaque structure is cut from a metal sheet - said radiopaque structure is produced by additive printing from a ceramic - the radiation protection device consists of a resin part mixed with at least one scintillator material in powder form.

[0023] The invention also relates to a radiation protection device for visualizing the interaction with the aforementioned ionizing radiation characterized in that it has the shape of a ruler, and contains an inclusion of a radio-opaque comb-shaped structure.

[0024] Advantageously it includes equipment for shooting the interaction zone between ionizing radiation and said ruler, and in that it includes an opaque cover to preserve the shooting field from ambient lighting.

[0025] According to one variant, it has the shape of a ring.

[0026] Detailed description of a non-limiting example of embodiment

[0027] The present invention will be better understood upon reading the following description, concerning a non-limiting example of an embodiment illustrated by the accompanying drawings where:

[0028] [Fig-1] [Fig.1] represents a schematic view of an installation for photographic recording.

[0029] [Fig.2] [Fig.2] represents a schematic view of a device for inserting a measuring fiber

[0030] [Fig.3] [Fig.3] represents a schematic view of an assembly for measuring the size of the field with rules according to the invention. Reminder of the goals of the invention

[0031] The invention aims to provide a solution for managing the risks associated with ionizing radiation by facilitating the identification of the presence of radiation, quantifying the size of the radiation field(s), and delimiting the affected areas. Indeed, exposure to ionizing radiation can be hazardous to health and lead to In some cases, harmful effects appear more or less rapidly depending on the type of exposure (i.e., deterministic effects in the form of tissue reactions such as radiation burns; or stochastic effects in the form of cancers or genetic abnormalities). However, since ionizing radiation is not visible to the naked eye, as is the case with X-rays or gamma rays, for example, it is impossible to detect its presence and reveal an exposed area without a detection tool.

[0032] This is particularly the case in medical imaging and radiotherapy, where checking the size of the exposure fields is mandatory and must be carried out periodically and after each intervention on the collimation system (see regulatory decisions below). The purpose of these checks is to verify the proper functioning of the machines and, in particular, the components responsible for emitting radiation (X-ray tube, beam collimators, etc.).

[0033] In medical imaging, poor machine performance, particularly in the radiation-emitting components, can lead to poor image quality. In such cases, obtaining a "diagnosable" image sometimes requires multiple attempts or adjustments to the machine parameters. The patient then risks being overexposed without real justification, which violates the ALARA (As Low As Reasonably Achievable) principle. This principle aims to obtain sufficient image quality for accurate diagnosis while minimizing the radiation dose delivered to patients.

[0034] In radiotherapy, an inappropriate field size can lead to poor treatment. The patient then risks overexposure of their healthy organs / tissues, which can lead to significant side effects, or conversely, underexposure of the area to be treated and therefore potentially a loss of treatment efficacy. Principles of the invention

[0035] The present invention relates to a system for detecting and / or delimiting a field of ionizing radiation (e.g. X-rays, electrons, hadrons...) to make it visible to the naked eye, usable in all fields using ionizing radiation (e.g., medical, industrial, nuclear, aerospace...).

[0036] To this end, the invention relates to a part formed by molding a resin, in particular an epoxy resin available in viscous form, combined with a hardener, to produce a homogeneous part after incorporating a scintillator in powder form into the resin. These scintillating compounds act as a fluorophore, that is to say, a molecule that has the property of emitting scintillation (fluorescence and / or phosphorescence).

[0037] The resin is marketed for example under the trade names EPODEX PRO™ of the company EPODEX™ or equivalent resins marketed under the trade names RESIN PRO™ or ECOPOXY™.

[0038] By way of example, for a scintillator made of strontium aluminate powder, of the formula SrA12O4: Eu2+, Dy3, marketed for example by the company Arco Iris™. The quantity – by volume – of scintillator is approximately 10% to a maximum of 15%. The scintillator can also be made of terbium-doped gadolinium oxysulfide (Gd2O2S: Tb) in powder form.

[0039] This scintillator, generally used to emit fluorescence under UV exposure, surprisingly possesses good fluorescence efficiency when placed in ionizing radiation fields such as low (<100keV) and high energy (>MeV) X-rays and has the advantage of low cost.

[0040] The scintillator powder is intimately mixed with the resin, avoiding the formation of bubbles or by de-bubbling, before the addition of the hardener and the pouring of the preparation into a mold having the desired shape (strip formed by a parallelepiped block, ring, bracelet, ...).

[0041] According to one embodiment, the invention also relates to a system for measuring the field size of ionizing radiation used in the context of quality assurance of medical equipment emitting ionizing radiation.

[0042] Among these checks, some consist of verifying the geometry of the beams and in particular the size of the irradiation field. In this specific case, since the radiation is not visible to the human eye, it is necessary to use equipment sensitive to the radiation in question and capable of reacting in such a way that the result of the reaction is visible.

[0043] In medical imaging, in addition to controlling the size of the field produced by the machine, there is also control of the size of the imaged field. In this case, an analysis of the images produced is necessary.

[0044] For these applications, a radio-opaque comb made by cutting or stamping a metal sheet or by additive printing of a ceramic is included in the mixture before hardening, to form an indexing structure with a millimeter pitch for example.

[0045] In the case of application in interventional radiology, dosimetric monitoring must be implemented for healthcare professionals exposed to radiation.

[0046] In the case of gamma radiography, an annual leak detection check is mandatory, zoning must be implemented for each use of the gamma radiograph, and medical monitoring must be implemented for operators.

[0047] Variant of coupling to a photographic recording system

[0048] Figure 1 shows a schematic view (camera, photo, webcam, other) for photographing the result. The device (11) according to the invention is placed in front of a lead screen (12) temporarily protecting a detector (13). A camera (14) takes an image of the assembly to allow measurement of the field covered by the ionizing radiation source (15) with a maximum Kerma rate. For this purpose, the device (11) consists of a ruler including a radiopaque comb with a millimeter pitch, for example, to provide a metrological reference.

[0049] The shooting system advantageously includes a cover allowing the camera, camcorder or other means of shooting to be in the dark and to improve sensitivity.

[0050] This cover consists of an opaque envelope surrounding the entire shooting area to improve contrast with ambient lighting and enhance sensitivity. This cover can serve as a support for the shooting device. Variant with insert

[0051] Figure 2 represents another variant where the device according to the invention is formed by a parallelepiped block (21) having a longitudinal channel (22) for the introduction of an optical fiber allowing the transmission of light to a photosensitive detector. Variant design in the form of strips

[0052] According to this embodiment, the devices produced are in the form of rulers (31, 32, 33, 34) measuring between 5 cm and 22.5 cm (4 rulers arranged in a cross) and 45 cm (two rulers arranged in a cross), as shown in [Fig. 3]. They are centered on the edges of the light field as schematically illustrated. In this embodiment, the rulers are smaller and their cost is therefore reduced. This measurement method allows for the simple characterization of field sizes, particularly when these are non-square or non-circular (hexagonal, orthogonal, etc.). The size of the light field is measured with a standard ruler, a plate, or any other graduated support. The ruler(s) is / are centered on the edge(s) of the light field. The difference between the light field and the X-ray field is directly evaluated. The graduations on the ruler are also radio-opaque so that the gap on the radiological image can be read directly.When the field in which the rulers (31 to 34) are placed is exposed to a light field and to a beam of ionizing radiation from a head (35), observation of the rulers reveals the shift between the two fields, which results in variations between the areas illuminated by white ambient light and the green fluorescent areas. Other use cases

[0053] Other embodiments of the invention relate to the application or integration of this optically active resin to form or coat gloves or other materials or fabrics used by healthcare professionals or civilians. The integration of this optically active resin into the materials used for making dosimetry rings and bracelets or into surgical gloves can also be considered. In this case, the compound is mixed with the plastic before molding. This optically active resin can also be applied in the form of a paint or varnish. The purpose of this embodiment is to alert the worker or civilian when they have the organ or body area within the radiation field and thus move away from it if possible.

Claims

Demands

1. A method for making a radiation protection device for visualizing interaction with ionizing radiation characterized in that it consists of preparing a homogeneous mixture of a resin and at least one scintillator material in powder form, then adding a hardener, mixing homogeneously and then pouring the mixture thus prepared into a mold to form a homogeneous part and in that said method comprises a step of including a radio-opaque comb-shaped structure in the mold.

2. Method of making a radiation protection device according to claim 1 characterized in that the resin is an epoxy type resin.

3. Method of making a radiation protection device according to claim 1 characterized in that the scintillator material is of the strontium aluminate type.

4. Method of making a radiation protection device according to claim 1 characterized in that the scintillator material is of the type terbium-doped gadolinium oxysulfide (Gd2O2S:Tb).

5. Method of making a radiation protection device according to claim 1 characterized in that said radio-opaque structure is cut out of a metal sheet.

6. Method of making a radiation protection device according to claim 1 characterized in that said radio-opaque structure is made by additive printing from a ceramic.

7. Radiation protection device for visualizing interaction with ionizing radiation characterized in that it consists of a ruler-shaped piece made of a resin mixed with at least one scintillator material in powder form, and containing an inclusion of a comb-shaped radio-opaque structure.

8. Radiation protection device for visualizing interaction with ionizing radiation according to the preceding claim characterized in that it further comprises equipment for taking pictures of the interaction zone between ionizing radiation and said ruler, and in that it comprises an opaque cover to preserve the field of view from ambient lighting.

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