Hybrid two-dimensional detector

Abstract

To provide a hybrid two-dimensional detector.SOLUTION: Regarding a detector (1) characterizing measurement of the dose of radiation, the detector includes an ionization detector (1IC) that is configured so as to measure the dose of radiation beams (5) propagating along the Z axis, includes an ionization box (ICi) dispersed to an entire section of a surface (X, Y) vertical to the Z axis, and has first spatial resolution over the entire section of the surface (X, Y), includes an additional detector (1A) that differs from the ionization detector (1IC), has second spatial resolution in the entire section of a surface (X, Y) higher than the first spacial resolution in the entire section of the surface (X, Y) of the ionization detector, and is placed in series along the Z axis relative to the ionization detector (1IC), and intelligence configured so as to obtain a calculation dose distribution from a dose (DICi) measured by the ionization detector (1IC) and a dose (D) measured by the additional detector (1A).SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to the field of detectors for measuring the dose of radiation (for example, a beam of protons, electrons, helium ions, carbon ions or oxygen ions, or a beam of electromagnetic radiation such as X-rays or γ-rays). The detector of the present invention depends on the high accuracy and low beam energy dependence of the means obtained by an ionization chamber having a much finer spatial resolution that can be utilized by the ionization chamber.

Background Art

[0002] Radiation therapy for the treatment of tumor cells within a patient is widely used. Various radiations can be considered, including beams of protons, electrons, helium ions, carbon ions or oxygen ions, or beams of electromagnetic radiation (for example, protons, preferably X-rays or γ-rays). The dose prescription is defined by a physician in the form of a treatment plan (TP), and the treatment planning system (TPS) optimizes the treatment plan (TP) to deliver the prescribed dose at a predetermined site.

[0003] Quality Assurance (QA) refers to the process of ensuring the quality of patient treatment (i.e., ensuring accurate and safe treatment). The dosimetry chain requires machine quality assurance and patient specific quality assurance (PSQA). The detectors of the present invention are suitable for both machine quality assurance and patient specific quality assurance, and are preferably but not exclusively applied to patient specific quality assurance (PSQA). Quality assurance is required to verify that the treatment delivery corresponds to the dose calculated by the TPS. For example, PSQA typically involves measuring the dosimetry parameters of the emitted radiation in 2D or 3D. The most common form of PSQA involves comparing the TPS dose calculation with 2D or 3D dosimetry measurements. The gamma evaluation method is widely used to compare such measurement results. Currently, the following two other forms of PSQA are being increasingly used in clinics: log-based QA and PSQA based on independent dose calculation by Monte Carlo simulation.

[0004] As shown in FIG. 2a, the 2D detector (1) is placed across the path of the radiation beam (5) propagating along the Z-axis. The 2D detector (1) measures the dose distribution on a "slice" within the plane (X, Y) perpendicular to the Z-axis as shown in FIGS. 1b and 2b. The 2D detector can be placed within a phantom (7) that defines the water equivalent thickness (WET) corresponding to the equivalent depth within the patient's body. As shown in FIGS. 2a, 2c, and 2d, the phantom can be a tank filled with water or other liquid. The phantom can also be made of plates of a given thickness and a given material with a known WET. The 3D dose distribution as shown in FIG. 1a can be obtained by placing several 2D detectors along the Z-axis as shown in FIG. 2c or by moving the 2D detector (1) along the Z-axis as shown in FIG. 2d. Thus, the dose distribution over several slices can be measured as shown in FIG. 2e, and the dose distribution along the Z-axis can be obtained as shown in FIGS. 1c and 2f.

[0005] Various detectors are known for measuring the dose accumulated by a given radiation in a given WET. One of the most widely used detectors is an ionization chamber detector (= IC detector) formed by an array of ionization chambers dispersed on a surface (X, Y) as described in (Patent Document 1). As shown in FIGS. 6b and 6c, the ionization chamber (ICi) is composed of two polarized electrodes (3-, 3+) separated by a gap (3g) filled with a fluid (preferably a gas, generally air, or a liquid). The fluid is ionized by radiation (5) crossing the ionization chamber (ICi) that forms charge ions. An electric field is generated by an external voltage source applied between the two polarized electrodes (3-, 3+). The charge ions are collected by an electrode that generates a measurable charge. For a given electric field applied to the ionization chamber, for a given design of the ionization chamber including the width of the gap, when the dimensions of the electrodes (3-, 3+) etc. are given, the dose measurement parameters including the radiation dose and distribution of linear energy transfer (LET) can be determined from the amplitude of the charge measured at the electrodes (3-, 3+) by a measurement device (e.g., a voltmeter or an ammeter) (3V).

[0006] However, the ionization chamber provides a limited spatial resolution on the order of mm (e.g., 5 to 8 mm) that severely limits the accuracy of the dose map constructed from the measurement results by the IC detector. It has been found that increasing the spatial resolution of the array of ionization chambers is very difficult because the signal-to-noise ratio rapidly deteriorates when the distance (t0x, t0y) separating adjacent ionization chambers is reduced.

[0007] Other detectors are available on the market. For example, 2D semiconductor-based detectors are an alternative to IC detectors and provide a significantly finer spatial resolution on the order of μm (e.g., 10 - 300 μm). Semiconductor detectors are solid-state detectors that detect radiation and convert it into charge. This can be achieved by using either direct conversion or indirect conversion. In a direct conversion detector, ionizing radiation directly generates electron-hole pairs in the semiconductor. Under the influence of an electric field, free electrons and free holes travel to the electrodes where the current can be measured. Indirect conversion detectors include scintillation detectors, which contain a scintillation layer that converts ionizing radiation into optical photons, and the optical photons are converted into charge by a photodetector. Some semiconductor-based detectors can also be used to quantify the linear energy transfer (LET) of particles. Thermoluminescence detectors are another type of indirect conversion detector.

[0008] However, the values measured by both direct conversion semiconductor detectors and indirect conversion semiconductor detectors show high energy dependence and can "quench" when exposed to particle radiation. The mechanism of ionization quenching is not fully understood, but the result is a detector response that deviates from the actual dose in regions with "high" linear energy transfer values. As shown in Figure 1c, the mechanism of ionization quenching is, for example, within the region of the Bragg peak by a clinical proton beam (compare the dashed line Bragg peak measured by the ionization chamber and the thick dotted line measured by the semiconductor detector exposed to quenching in Figure 1c).

[0009] Subsequently, direct conversion detectors are called "semiconductor detectors", and indirect conversion detectors are called "scintillation detectors" or "thermoluminescence detectors".

[0010] There is a need to develop a new generation of dosimetry detectors specialized for PSQA. This new generation of detectors should provide a fast and accurate response with high spatial resolution under various conditions, including not only conventional dose rates and doses but also ultra-high dose rates and high doses (also known as FLASH) irradiation, various types of particles, various delivery modalities (scattered beam, scanned pencil beam), various beam time structures (pulsed beam, continuous beam), and so on.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

[0012] The present invention proposes a detector that characterizes radiation dosimetry by combining high accuracy, high precision, and high spatial resolution with a significantly low energy dependence of the measured values. These and other advantages of the present invention will be described in more detail in the following sections.

Means for Solving the Problems

[0013] The present invention relates to a detector for characterizing radiation dosimetry, including an ionization detector configured to characterize the dosimetry of a radiation beam propagating along the Z-axis. The radiation beam can be a beam of charged particles (preferably protons, electrons, helium ions, carbon ions, or oxygen ions) or a beam of electromagnetic radiation (preferably photons, more preferably X-rays or gamma rays).

[0014] The ionization detector includes a matrix of ionization boxes distributed across the entire plane (X,Y) perpendicular to the Z-axis. Each ionization box includes a first and a second electrode separated by a medium, where the ionization detector has a first spatial resolution across the plane (X,Y).

[0015] An additional detector (1A) different from the ionization detector, the additional detector (1A) having a second spatial resolution over the entire surface (X,Y) that is finer than the first spatial resolution over the entire surface (X,Y) of the ionization detector, is placed in series with the ionization detector along the Z-axis. The detector includes or is coupled to an intelligence configured to calculate a dose distribution calculated from the dose measured by the ionization detector and the dose measured by the additional detector.

[0016] The additional detector may be selected from the group consisting of semiconductor detectors, scintillation detectors, thermoluminescence detectors, membranes, chemical detectors including polymer gels, and alanine detectors.

[0017] The ionization detector has a thickness measured along the Z-axis, and the additional detector has a thickness measured along the Z-axis. The detector having a thickness that results in the lowest water equivalent thickness (WET) for a given radiation is preferably placed upstream along the Z-axis with respect to the radiation beam. For example, the additional detector can be a semiconductor detector placed upstream of the ionization detector along the Z-axis with respect to the radiation beam. Alternatively, the additional detector can be a scintillation detector placed downstream of the ionization detector along the Z-axis with respect to the radiation beam.

[0018] The detector has a thickness (t1) that is preferably less than 100 cm, more preferably less than 70 cm, more preferably less than 50 cm, more preferably less than 10 cm, or less than 5 cm, measured along the Z-axis. A detector (1) having a physical thickness (t1) within the upper limit range includes, for example, a scintillator detector as an additional detector (1A), and the scintillator detector requires not only a thin scintillation plate but also optical structures (such as mirrors and photodetectors like a camera (e.g., a CCD camera) that significantly increases the thickness (1A,t1) of the additional detector (1A) and thus the detector (1)). A detector having a physical thickness (t1) within the lower limit range may include, for example, a semiconductor detector as an additional detector (1A). The distance (tIC-A) between the effective measurement point of the ionization detector and the effective measurement point of the additional detector is preferably 5 cm or less, preferably 2 cm or less. In some embodiments, the IC detector (1IC) and the additional detector (1A) may even be in contact with each other, reducing the distance close to 0 (i.e., tIC-A→0). The thickness (t1) of the detector (1) is 5 g / cm 2 is preferably adapted to correspond to the following WET.

[0019] In a preferred embodiment, the ionization chambers are distributed over the entire surface (X,Y) of the ionization detector, and the surface (X,Y) of the ionization detector is cm 2 has at least 1 ionization chamber (IC) per cm, preferably 2 has a resolution of at least 1.5 ionization chambers (ICi) per cm. It is preferred that the additional detector has a pixel resolution that is at least twice the resolution of the ionization detector. The additional detector may have a resolution of at least 50 pixels / cm 2 or at least 70 pixels / cm 2 or at least 100 pixels / cm 2 respectively.

[0020] The intelligence is preferably also configured to determine the distribution of the linear energy transfer (LET) of the radiation from the measured dose.

[0021] In a preferred embodiment, each ionization chamber is separated from an adjacent ionization chamber of the same ionization detector by only an inter chamber space. One or more sensors (Aij) of the additional detector face the ionization chamber of the ionization detector, and one or more sensors of the additional detector face the inter chamber space. The sensors of the additional detector have a higher energy dependence than the ionization chamber of the ionization detector. The calculated dose Dij in the unit volume enclosed in or intersecting the detector at the level of the ionization chamber is a function Dij = f(DAij, DICi) of the dose DICi measured by the ionization chamber and the dose DAij measured by a given sensor of the additional detector facing the ionization chamber along the Z axis. Preferably, the function Dij = f(DAij, DICi) also depends on one or more of the following doses: ● the dose DICia measured by the neighboring ionization chamber adjacent to the unit volume, ● the dose DAija measured by the neighboring sensor of the additional detector facing the ionization chamber (and preferably adjacent to a given sensor), and ● the dose DA0ja measured by the neighboring sensor of the additional detector facing the inter chamber space adjacent to the unit volume.

[0022] The calculated dose (Dij) may depend on a sub - function f1(DICAij) (i.e., Dij = f(DAij, DICi, f1(DCAij))) that relates the dose measured by the ionization chamber (DICi) and the dose measured by the sensor of the additional detector facing the ionization chamber along the Z axis (DAij). The sub - function f1(DICAij) is preferably the ratio (DICi / DAij) or the difference (DICi - DAij) between the dose measured by the additional detector and the dose measured by the ionization detector (DAij and DICi).

[0023] In a preferred embodiment, at least one sensor of the additional detector faces the inter chamber space. The calculated dose (D0j) at the level of a given sensor enclosed in the intermediate unit volume intersecting the detector in the inter chamber space between adjacent ionization chambers is a function D0j = g(DA0j, DICia, DAija) of at least the following doses: ● The dose (DA0j) measured by a given sensor of the additional detector, and one or more of the following, ● The dose (DICia) measured by the neighboring ionization chambers adjacent to the intermediate unit volume, and one or more of the following ● The dose (DA0ja) measured at least by the neighboring sensors of the additional detector enclosed within the same intermediate volume and adjacent to a given sensor, and ● The dose (DAija, i>0) of the neighboring sensors of the additional detector facing the neighboring ionization chambers.

[0024] The present invention also relates to a dose measurement characterization unit configured to characterize the dose measurement in the plane (X, Y) of a radiation beam propagating over the entire Z-axis perpendicular to the plane (X, Y) at various positions (k = 1 to K, K>1)) along the Z-axis separated from each other by a distance (tk). The dose measurement characterization unit includes the aforementioned detector placed at the position (k), and is one of the following: ● Further includes (K-1) defined neighboring detectors aligned with the detector along the Z-axis and placed at their respective positions (k+m; m≠0), or ● The detector is configured to be moved to various positions.

[0025] In a preferred embodiment, the detector and preferably the neighboring detectors are as described above, and the calculated dose (Dij, D0j) in the unit volume enclosed within or intersecting the detector at the level of the ionization chamber (ICi) is a function Dij = f(DAij, DICi), and preferably a function (D0j = g(DA0j, DICia, DAija)). The functions Dij = f(DAij, DICi) and / or D0j = g(DA0j, DICia, DAija) determined at the position (k) are also one or more of the following functions: ● The dose (DAija) measured by the corresponding sensor at the positions ((k-1); (k+1)) directly adjacent to the position (k), and / or ● The dose (DA0ja) measured by the corresponding sensor at the positions ((k-1); (k+1)) directly adjacent to the position (k).

[0026] The present invention also relates to a method for characterizing the dosimetry of a radiation beam propagating along the Z-axis, the method comprising the following: ● Placing a previously defined dosimeter perpendicular to the Z-axis, ● Propagating a radiation beam along the Z-axis across the dosimeter, ● Measuring the dose (DICi, DAij, DA0j) by the ionization detector and additional detectors of the dosimeter, ● Calculating the calculated dose (Dij, D0j) according to the dose (DICi, DAij, DA0j) thus measured.

[0027] These and other aspects of the invention will be described in more detail by way of example and with reference to the accompanying drawings.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0029] As shown in Figure 6a, a detector (1) characterizing the dose measurement of a radiation beam (5) according to the present invention includes an ionization detector (1IC) and an additional detector (1A) aligned along the Z-axis, and both the ionization detector (1IC) and the additional detector (1A) are configured to characterize the dose measurement of the radiation beam (5) propagating along the Z-axis. The radiation beam (5) can be a beam of charged particles (preferably protons, electrons, helium ions, carbon ions or oxygen ions), or a beam of electromagnetic radiation (preferably photons, more preferably X-rays or gamma rays).

[0030] The ionization detector (1IC) includes a matrix of ionization chambers (ICi) distributed across the entire plane (X,Y) perpendicular to the Z-axis. As shown in FIGS. 6b and 6c, each ionization chamber (Ici) includes first and second electrodes (3-, 3+) separated by a medium (preferably a gas or liquid such as air). The ionization detector has a first spatial resolution across the entire plane (X,Y).

[0031] The additional detector (1A), unlike the ionization detector (1IC), has a second spatial resolution across the entire plane (X,Y) that is finer than the first spatial resolution across the entire plane (X,Y) of the ionization detector (Ici). The additional detector is placed in series along the Z-axis with respect to the ionization detector (1IC).

[0032] The detector also includes or is coupled to intelligence configured to calculate the distribution of the calculated dose (Dij) from the dose (DICi) measured by the ionization detector (1IC) and the doses (Daij, DA0j) measured by the additional detector (1A).

[0033] Detector configuration for quality assurance As shown in FIGS. 1b, 2a, and 2b, the detector (1) for quality assurance (preferably for PSQA) according to the present invention is a 2D detector configured to characterize the dose measurement of the radiation beam (5) in the plane (X,Y) perpendicular to the radiation beam propagating along the Z-axis. The desired depth within the patient of the plane (X,Y) can be simulated by placing the detector (1) within the phantom (7) at the corresponding water equivalent thickness (WET). The phantom is typically formed by a tank filled with water. The phantom can also be filled with different liquids or formed of solid plates of known WET and given thickness. Accordingly, the detector (1) is placed at the relevant strategic depth or WET. For example, with respect to a proton beam, the plane (X,Y) preferably intercepts the Bragg curve.

[0034] As shown in FIGS. 1a, 1c and FIGS. 2c-2f, the 3D dose distribution map can be obtained by combining dose distributions along various planes (X, Y) dispersed along the Z-axis. This can be obtained by aligning a plurality of detectors (1) along the Z-axis or by moving a single detector along the Z-axis (e.g., along the rail shown in FIG. 2d) by a dose measurement characterization unit as shown in FIG. 2c.

[0035] However, the detector configurations previously described and shown in FIGS. 2a-2f require that the detectors used exhibit sufficiently high spatial resolution and sufficiently high accuracy, precision, and reliability. In particular, the values measured by the detector shall be independent of the quenching effect. However, as previously discussed in the "Background Art" chapter, this combination is not satisfactorily achieved by ionization chambers based on detectors currently available on the market. This is achieved by the detector (1) of the present invention including ionization detectors (1IC) and additional detectors (1A) aligned in series along the Z-axis.

[0036] Ionization detector (1IC) As shown in FIGS. 4a and 6a, the ionization detector (=IC detector) is formed by an array of ionization chambers (ICi) dispersed on the plane (X, Y). The ionization chamber (ICi) includes first and second electrodes (3-, 3+) separated by a medium (preferably a gas or liquid such as air). As shown in FIGS. 6b and 6c, the electrodes (3-, 3+) can be planar electrodes parallel to each other or concentric cylindrical electrodes as shown in FIGS. 6b and 6c. The current generated between the electrodes by the ionized molecules of the medium traversed by the radiation beam (5) is measured by a measurement unit (3V) such as a potentiometer.

[0037] Each ionization cell (ICi) has a width (tICy) and a height (tICx) measured along the Y-axis and X-axis respectively (see FIGS. 6a and 6d). The physical thickness along the Z-axis of each ionization cell (ICi) is not as important as its WET. It is preferable that the WET of the ionization cell be as low as possible: that is, it is preferable that the radiation beam (5) loses as little energy as possible when traversing the ionization chamber (ICi). This is particularly important if the ionization detector (1IC) is placed upstream of the additional detector (1A). When several detectors (1.k) are aligned in series along the Z-axis as shown in FIG. 2c, it is also important to establish a 3D dose accumulation mapping of the radiation beam (5).

[0038] The ionization chambers (ICi) are separated from each other by a distance (t0x, t0y) along the X-axis and Y-axis respectively. The spatial resolution of the IC detector (1IC) depends on the one hand on the dimensions (tICx, tICy) of the ionization chambers (ICi) and on the other hand on the distance (t0x, t0y) separating adjacent IC chambers (ICi). The response of the ionization chamber regarding well-known effects (temperature, pressure, polarity, recombination) has to be corrected in a manner well known to the person skilled in the art. The dimensions of the ionization chambers (ICi) are physically and technically limited. Reducing the distance (t0x, t0y) separating adjacent ionization chambers is limited by the resulting rapid deterioration of the signal-to-noise ratio. As a result, the spatial resolution of the IC detector (1IC) is limited and thus cannot currently be substantially increased. The ionization chambers (ICi) are distributed over the entire surface (X, Y) of the ionization detector (1IC) (cm 2 with at least one ionization chamber (IC) per cm (preferably cm 2 with at least 1.5 ionization chambers (ICi) per cm) resolution). It is also preferable that the additional detector (1A) has a pixel resolution that is at least twice that of the ionization detector (1IC).

[0039] However, the value (DICi) measured by the IC detector (1IC, 1IC.k) is highly reliable and not sensitive to quenching. FIG. 4a shows a series of several IC detectors (1IC) that are distributed along the Z-axis and perpendicular thereto and intersect the radiation beam (5). FIG. 4b shows the dose values measured by the various IC detectors of FIG. 4a aligned along the Z-axis, which are obtained by combining the dose values measured by each IC detector (1IC) of the series of IC detectors of FIG. 3a at the same position along the X-axis. The values measured by each ionization cell (ICi) of each IC detector (1IC) that intersects the (Y, Z) plane are represented by shaded squares dispersed on the (Y, Z) plane over the entire predicted Bragg curve, and their thickness (tICz) is measured along the Z-axis. It can be seen that although the dose value (DICi) measured by each ionization cell (ICi) conforms to the predicted beam shape in each (X, Y) plane as shown in FIG. 1b (thin dashed line), the spatial resolution is insufficient to satisfactorily characterize the beam. The IC detector (1IC) has a first spatial resolution over the entire (X, Y) plane on the order of mm (e.g., 5 - 8 mm).

[0040] Additional detector (1A) The additional detector (1A) must be different from the IC detector (1IC) and must have a second spatial resolution over the entire (X, Y) plane that is finer than the first spatial resolution over the entire (X, Y) plane of the IC detector (1IC). The additional detector (1A) preferably has a pixel resolution that is at least twice the resolution of the ionization detector (1IC). For example, the additional detector (1A) can have at least 50 pixels / cm 2 and preferably at least 100 pixels / cm 2 of resolution.

[0041] The additional detector (1A) can be selected from the group consisting of semiconductor detectors, scintillation detectors, thermoluminescence detectors, films, chemical detectors including polymer gels, and alanine detectors. The additional detector (1A) is preferably a semiconductor detector or a scintillation detector.

[0042] Figure 3a shows an example of a series of additional detectors (1A, 1A.k) that are aligned along the Z-axis and perpendicular thereto and are traversed by a radiation beam (5). Each additional detector (1A) is formed by a series of sensors (Aij, A0j) distributed across the corresponding surface (X, Y). As can be seen in Figure 6d, the dimensions of the sensors (Aij, A0j) are substantially smaller than the dimensions of the ionization chambers (ICi) of the IC detector (1IC), and the sensors of the additional detector are separated from each other by a substantially smaller distance than the ionization chambers (ICi) of the IC detector (1IC). This results in a very dense series of sensors with an accordingly increased spatial resolution. However, many additional detectors (1A) including semiconductor detectors are sensitive to quenching when traversed by a high-energy particle radiation beam (5). This can be the case, for example, within the region of the Bragg peak of a proton beam. In the embodiment shown in Figure 3a, the additional detector (1A) is a semiconductor detector and the sensors (Aij, A0j) are semiconductors.

[0043] The scintillation detector includes a series of scintillation layers. In response to the incident radiation beam (5), each scintillation layer generates an amount of photons that depends on the dose accumulated by the radiation beam. These are collected by a photodetector (e.g., a camera) that converts the optical energy into electrical energy whose amplitude can be measured.

[0044] Figure 3b shows the dose distribution across the surface (Y, Z) obtained by combining the dose values measured by each semiconductor detector (1A) of the series of semiconductor detectors of Figure 3a at the same position along the X-axis. Different from the IC detector results plotted in Figure 4b, the spatial resolution of the dose distribution plotted in Figure 3b and measured by the semiconductor (additional) detectors (1A, 1A.k) of Figure 3a is high, having a second spatial resolution on the order of μm (e.g., 10 - 300 μm). However, the absolute values (DAij, DA0j) obtained by the additional detectors of Figure 3a are not reliable due to the quenching effect observed at high energies (having a Bragg peak with a flat geometry).

[0045] Figures 1b, 3b and 4b show this. Neither the IC detector (1IC) nor the additional detector (1A) (e.g., a semiconductor detector) can satisfactorily characterize the dose measurement of the radiation beam (5) (due to either poor spatial resolution or poor reliability of the results in a high-energy particle beam). The detector (1) of the present invention solves this problem by combining the advantages of both detectors and compensating for their respective drawbacks.

[0046] Detector (1) of the present invention = combination of an IC detector (1IC) and an additional detector (1A) Since all existing detectors have advantages but also unsatisfactory drawbacks, the present invention combines the advantages of various detectors in order to reduce and even neutralize their corresponding drawbacks. The detector (1) of the present invention includes an IC detector (1IC) having a first spatial resolution, and an additional detector (1A) placed in series along the Z-axis and having a second spatial resolution finer than the first spatial resolution. FIG. 6a shows an example of a detector (1) according to the present invention including an IC detector (1IC) and an additional detector (1A) (a semiconductor detector in this embodiment). The two detectors (1IC, 1A) are coupled in series along the Z-axis and separated from each other by a distance (tIC-A). For example, the distance (tIC-A) between the effective measurement points of the ionization detector (1IC) and the additional detector (1A) is preferably 5 cm or less, which preferably corresponds to 5 g / cm 2 Corresponds to the following WET.

[0047] The additional detector (1A) has a physical thickness (tA) such that it has a physical thickness (t1) measured along the Z-axis of t1 = tIC + tA + (tIC-A), and the IC detector (1IC) has a physical thickness (tIC). For example, the detector (1) can have a measured physical thickness (t1) along the Z-axis of less than 100 cm as previously discussed.

[0048] Among the IC detector (1IC) and the additional detector (1A), the detector having the physical thicknesses (tIC, tA) that produce the lowest water equivalent thickness (WET) for a given radiation has the lowest energy absorption effect on the cross-radiation beam (5) before reaching the second detector placed downstream. Therefore, it is preferably placed upstream along the Z-axis with respect to the radiation beam (5). For example, as shown in FIG. 6a, the additional detector (1A) can be a semiconductor detector placed upstream of the ionization detector (1IC) along the Z-axis with respect to the radiation beam (5). Alternatively, the additional detector (1A) can be a scintillation detector placed downstream of the ionization detector (1IC) along the Z-axis with respect to the radiation beam (5). The scintillation detector alone may have a lower WET than the IC detector (1IC), but the scintillation detector is usually equipped with optical elements including mirrors and cameras or photodetectors that can significantly increase the corresponding WET.

[0049] The detector (1) of the present invention measures the dose (DICi) by the IC detector (1IC) and measures the dose (DAij, DA0j) by the additional detector (1A). The dose (DAij) is measured by the sensor (Aij) facing directly the corresponding ionization cell (ICi) of the IC detector (1IC), and the dose (DA0j) is measured by the sensor (A0j) facing directly the inter-box space separating adjacent ionization cells (ICi) of the IC detector (1IC). FIG. 6d shows the positions (Aij, A0j) of the sensors of the additional detector (1A) with respect to the ionization boxes (ICi) of the IC detector (1IC) in the front view of the detector (1). The intelligence (10) collects and uses the dose values (DICi, DAij, DA0j) measured by the IC detector (1IC) and the additional detector (1A) forming the detector (1) of the present invention to determine the calculated dose distribution (Dij, D0j) having the accuracy, precision, and reliability of the IC detector and the second spatial resolution of the additional detector (1A).

[0050] Figure 5b shows the calculated dose distribution over the entire plane (Y,Z) measured by the series of detectors (1, 1.k) shown in Figure 5a and calculated by the intelligence (10). The detector (1) is formed of a semiconductor detector shown in Figure 3a aligned upstream of the IC detector (1IC) as shown in Figure 4a. The calculated dose distribution (Dij = f(DAij, DA0j, DICi)) shown in Figure 5b characterizes the Bragg curve of the proton beam (5) in Figure 5a with high reliability, accuracy, and precision and with high spatial resolution. The intelligence (10) is preferably also configured to calculate other dose measurement parameters (such as the distribution of the linear energy transfer (LET) of the radiation) from the measured doses (DICi, DAij, DA0j).

[0051] Intelligence (10) and calculated dose distribution (Dij) As shown in Figures 5a and 6a, the detector (1) of the present invention includes or is coupled to an intelligence (10) (represented as a laptop in the figure), but can take any other shape and format known in the art (such as an integrated circuit attached to or inserted into the detector (1)). The intelligence (10) is configured to calculate the distribution of the calculated doses (Dij, D0j) from the dose (DICi) measured by the ionization detector (1IC) and the doses (DAij, DA0j) measured by the additional detector (1A).

[0052] As shown in Figures 6d and 9a, at least one (preferably two or more) sensors (Aij) of the additional detector (1A) face the ionization chamber (ICi), and at least one (preferably two or more) sensors (A0j) of the additional detector (1A) face the inter-chamber space. Thus, the additional detector (1A) has a greater number of sensors (Aij, A0j) than the number of ionization chambers (ICi) of the IC detector, and thus gives the additional detector a second spatial resolution finer than the first spatial resolution of the IC detector.

[0053] The sensor (Aij) is identical to the sensor (A0j), and the various nomenclatures refer to their positions only with respect to the ionization chamber (ICi). The index "i" refers to the corresponding ionization chamber (ICi) that the sensor (Aij) faces, and the index "0" indicates that the sensor faces the inter-room space. The index "j" counts the sensors according to their positions with respect to the ionization chamber (ICi). For example, in Fig. 6d, four sensors (Aij) numbered Ai1, Ai2, Ai3, and Ai4 face each ionization chamber (ICi) (not all sensors are labeled in Fig. 6d for clarity). Similarly, the sensors (A0j) facing the inter-box space are numbered A01, A02, …, A0j, …. To account for the fact that the sensor (Aij) is not different from the sensor (A0j), the following nomenclature is continuously used: ● ICi and DICi refer to the ionization chamber and the i-th dose measured thereby. The index "i" in ICi and DICi is never equal to zero, i.e., when ICi and DICi are cited, it is necessarily i > 0 without the need to specify this. ● Aij, DAij, i ≧ 0 refer to all sensors of the additional detector (1A) and the dose measured thereby, where ○ The sensor Aij, i > faces the corresponding ionization chamber (ICi), and ○ The sensor Aij, i = 0 faces the inter-box space. Therefore, when referring to Aij or DAij, it is necessary to specify whether i > 0 (thus excluding A0j and DA0j) or i ≧ 0 (thus including A0j and DA0j). ● Dij, i ≧ 0 refers to the calculated dose calculated from the values of DICi and DAij, where ○ Dij, i > 0 refers to the value calculated from the dose measured by the sensor Aij, i > 0, and ○ Dij, i = 0 refers to the value calculated from the dose measured by the sensor Aij, i = 0. Therefore, when referring to Dij, it is necessary to specify whether i > 0 (indicating that Dij is calculated for sensor Aij where i > 0 (i.e., excluding A0j)), or, therefore, Dij where i ≥ 0 indicates that it is calculated for sensors Aij where i ≥ 0 (i.e., all sensors including A0j).

[0054] The sensors of the additional detector (Aij where i ≥ 0) have a higher energy dependence than the ionization chambers (ICi) of the ionization detector (1IC), and thus cannot be safely used alone to determine that "the dose as the value measured thereby is not at all reliable in the case of an additional detector (1A) quenched due to exposure to a radiation beam (5) having too high an energy."

[0055] Judgment of the calculated dose Dij where i > 0 The calculated dose (Dij where i > 0) within the unit volume intersecting the detector (1) at the level of the ionization chamber (ICi) can be a function Dij = f(DAij, DICi) where i > 0 of the dose (DICi) measured by the ionization chamber (ICi) and the dose (DAij where i > 0) measured by a given sensor (Aij where i > 0) of the additional detector (1A) facing the ionization chamber (ICi) along the Z-axis. This is shown in FIGS. 7a and 7b. FIG. 7a shows the single dose (DICi) measured by one ionization chamber (ICi) over the entire area of the ionization chamber (ICi) in the plane (X, Y). FIG. 7a also shows the various dose values (DAij where i > 0) measured by the sensors (Aij where i > 0) facing the ionization chamber (ICi). It can be seen that the additional detector (1A) has a higher spatial resolution than the IC detector (1IC). However, the dose values (DAij where i > 0) measured by the sensors (Aij where i > 0) of the additional detector (1A) are lower than the single value (DICi) measured by the ionization chamber (ICi) of the IC detector (1IC), indicating that the additional detector (1A) is troubled by the quenching effect and renders the dose values (DAij where i > 0) unreliable.

[0056] FIG. 7b shows that "the dose (Dij, i>0) can be characterized by accuracy, precision, and high spatial resolution by calculating the dose (Dij, i>0) according to the dose (DAij, i>0) measured by the additional detector (1A) corrected so that the dose distribution over the entire area of the ionization chamber (ICi) fits the dose (DICi) measured by the IC detector (1IC) according to the calculated dose (Dij, i>0)".

[0057] The function f(DICi, DAij) for determining the value of the calculated dose (Dij, i>0) can take multiple forms, and the present invention is not limited to a single function. The essential thing is that the calculated dose (Dij, i>0) is calculated based at least on the dose (DICi) measured by the IC detector (1IC) and the dose (DAij, i>0) measured by the additional detector (1A). For example, the calculated dose (Dij, i>0) may depend on a sub-function f1(DICAij) that relates the dose (DICi) measured by the ionization chamber (ICi) to the dose (DAij, i>0) measured by the sensor (Aij, i>0) of the additional detector facing the ionization chamber (ICi) along the Z-axis (i.e., Dij = f(DAij, DICi, f1(DCAij)), i>0). The sub-function f1(DICAij) can be the ratio (DICi / DAij) or the difference (DICi - DAij) between the doses (DAij and DICi) measured by the additional detector (1A) and the ionization detector (1IC).

[0058] For example and as shown in FIGS. 7a and 7b, the function f1(DCAij) is the difference TIFF2025102716000002.tif6170, i>0) between the dose (DICi) measured by the ionization chamber (ICi) and the average dose TIFF2025102716000003.tif6170, i>0) measured by the sensor (Aij, i>0) of the additional detector (1A) facing the ionization chamber (ICi). It can be. Next, the calculated dose (Dij) is TIFF2025102716000004.tif6170, i > 0 can be. The average dose ( TIFF2025102716000005.tif6170, i > 0) measured by the sensor (Aij, i > 0) of the additional detector (1A) facing the ionization chamber (ICi) is used, which makes sense because the single dose value (DICi) measured by the ionization chamber (ICi) is an averaged value over the entire area (tICx × tICy) of the ionization cell (ICi).

[0059] It is obvious that "if no quenching occurred on the additional detector (1A) during the QA measurement, the sub - function f1(DAICij) = 0, and no correction of the values (DAij, i ≥ 0) measured by the sensor (Aij, i ≥ 0) of the additional detector (1A) is required".

[0060] In an alternative example, the function f1(DCAij) can be the ratio of the dose (DICi) measured by the ionization chamber (ICi) to the average dose ( TIFF2025102716000006.tif6170, i > 0) measured by the sensor (Aij, i > 0) of the additional detector (1A) facing the ionization chamber (ICi). TIFF2025102716000007.tif6170, i > 0). Next, the calculated dose (Dij, i > 0) can be expressed as TIFF2025102716000008.tif6170, i > 0. Other forms of the functions f(Aij, DICi, f1(DCAij)) and f1(DCAij) that are well within the ability and reach of a person skilled in the art are of course possible.

[0061] In the preferred embodiment shown in Figure 9a, the calculated dose (Dij, i > 0) also depends on one or more of the following measured doses: ● The dose (DICia) measured by the ionization chamber (ICia) adjacent to the unit volume, and / or ● The dose (DAija, i≧0) measured by the sensors (Aija, i≧0) of the additional detectors (1A) adjacent to the given sensor (Aij), including the following doses: ○ The dose (DAija, i>0) measured by the neighboring sensors (Aija, i>0) facing the ionization chamber (ICi) (preferably at least by the neighboring sensors directly adjacent to the given sensor (Aij)), and / or ○ The dose (DA0ja) measured by the neighboring sensors (A0j) facing the inter-box space adjacent to the unit volume.

[0062] By taking into account the doses (DAija, DICia) measured by the adjacent sensors (Aija) and / or the adjacent ionization chambers (ICia), it is possible to obtain a continuous (preferably smooth) dose distribution curve on the surface (X, Y). For example, the condition of having a continuous derivative between the calculated dose (Dij) derived from a given sensor (Aij) and the calculated doses (Dija) derived from the adjacent sensors (Aija) and the adjacent ionization chambers (ICia).

[0063] It is obvious that "the function f1(DCAij) can also be applied by taking into account the dose (DICia) measured by the adjacent ionization chamber (ICi) and / or the dose (DAij, i≧0) measured by the neighboring sensors (Aij, i≧0) of the additional detector (1A)".

[0064] Figures 8a and 8b schematically show the determination of the calculated doses (Dij, i≧0), where for each sensor (Aij, i≧0), in addition to the doses (DICi, DAij) measured by the corresponding ionization chamber (ICi) and the sensor (Aij), the following calculated doses (Dij) are also considered: ● The dose (DICia) including the doses (DIC(i+1), DIC(i+1)) measured by the adjacent ionization chambers (IC(i+1), IC(i+1)) and Dose (DAija, i≧0) including doses (DAij, DAi(j+1), DA(i+1)j, DAi(i+1)(j+1), DA0j, DA0(j+1), etc.) measured by adjacent sensors (Aija, i≧0) including sensors (such as Aij, Ai(j+1)j, A(i+1)j, Ai(i+1)(j+1), A0j, A0(j+1), etc.) (not shown).

[0065] By considering the signals of adjacent sensors (Aija) and / or neighboring ionization chambers (ICia) for the determination of the calculated value of the dose (Dij), it is ensured that the calculated dose distribution over the entire surface (X, Y) is continuous and preferably smooth.

[0066] Determination of the calculated dose D0j The determination of the calculated dose (D0j) in the intermediate unit volume intersecting the detector (1) at the level of the inter-chamber space between neighboring ionization chambers (ICia) adjacent to the inter-chamber space can be performed as follows. In the first embodiment, the calculated dose (D0j) in the inter-chamber space can be simply interpolated between the calculated doses (Dij, i>0) of two or more adjacent ionization chambers (ICi) surrounding the inter-chamber space.

[0067] In a preferred embodiment, the calculated dose (D0j) in the intermediate unit volume is determined as follows. First, the additional detector (1A) must include at least one (preferably two or more) sensors (A0j) facing the inter-chamber space of the IC detector (1IC). As shown in FIG. 9b, the calculated dose (D0j) at one level of a given sensor (A0j) enclosed in the intermediate unit volume can be a function D0j = g(DA0j, DICia, DA0ja, DAija) of at least one of the following doses: ● Dose (DA0j) measured by a given sensor (A0j) of the additional detector (1A), ● Dose (DICia) measured by a neighboring ionization chamber (ICia) adjacent to the intermediate unit volume, and one or more of the following doses: ● The dose (DA0ja) measured by the neighboring sensor (A0ja) of the additional detector (1A) enclosed within the same intermediate volume and adjacent to a given sensor (A0j), and ● The dose (DAija, i>0) of the neighboring sensor (Aija, i>0) of the additional detector (1A) facing the neighboring ionization chamber (ICia).

[0068] High-resolution 2D dose distribution on the plane (X,Y) and 3D dose distribution within the volume (X,Y,Z) The high-resolution 2D dose distribution on the plane (X,Y) by the radiation beam (5) shown in Fig. 1b (thin dashed line) can be obtained by determining the calculated dose (Dij, i≧0) at the levels of all sensors (Aij, i≧0) including the sensors (Aij, i>0) facing the ionization chamber (ICi) and the sensors (A0j) facing the space between the chambers, as previously discussed.

[0069] The high-resolution 3D dose distribution map on the volume (Y, Z) at a predetermined position along the X-axis shown in FIGS. 1a and 5b can be obtained by establishing high-resolution 2D dose distribution maps at various positions (k) along the Z-axis corresponding to various depths within the patient's body. This can be achieved by a dosimetry characterization unit including either a plurality of detectors (1.k) aligned at corresponding positions (k = 1 to K, K>1) along the Z-axis as shown in FIG. 2c or a single detector (1) configured to be moved to various positions (k = 1 to K, K>1) along the Z-axis as shown in FIG. 2d. In either case, the dose distribution measured along the Z-axis is discrete corresponding to the discrete positions (k) of the single or plurality of detectors (1, 1.k) during measurement. Aligning a plurality of detectors (1.k) as shown in FIG. 2c has the advantage that the characterization can be done by a single measurement execution. The disadvantages are, on the one hand, that a plurality (K) of detectors (1.k, k = 1 to K) are required and, on the other hand, that a part of the energy of the radiation beam (5) is released to interact (which can impair values at greater depths along the Z-axis) with each of a series of detectors (1.k) depending on the number (K) of detectors used. Using a single detector (1) moved to various positions (k) along the Z-axis has the advantage of requiring only a single detector (1). The disadvantage is that several (K) measurements have to be repeated, which takes more time as the detector has to be moved (1) along the Z-axis to its new position and (2) reset before starting the next measurement execution.

[0070] Thus, the dosimetry characterization unit includes a detector (1) placed at the position (k) (as discussed previously), ● further including the same (K-1) adjacent detectors (1.k) aligned with the detector (1) along the Z-axis as shown in FIG. 2c and aligned with the detectors (1) arranged at their respective positions (k + m; m≠0), or ● The detector (1) is configured to be moved to various positions (k) as shown in Fig. 2d. Fig. 2d shows the detector (1) mounted on a rail, but the rail is not essential. It is sufficient that the detector (1) can be fixed at various positions (k).

[0071] As shown in Figs. 1a and 5b, to determine the calculated dose distribution on the plane (Y, Z), or as shown in Fig. 1c, to determine the dose distribution along the Z-axis (which is nothing but the intersection of the surface of Fig. 1a and the plane y = 0 represented by the dashed line in Fig. 1a), the calculated dose distribution along the Y-axis can be determined independently for each position (k) and its value can be plotted along the Z-axis. This is shown in Fig. 2e which shows the calculated dose distribution along the plane (X, Y) at various positions ((k - 1), k, (k + 1)) along the Z-axis. Fig. 2f shows the alignment along the Z-axis at each position (k) of the calculated dose distribution over the entire plane (X, Y) of Fig. 2e (only half of the dose distribution (y ≥ 0) is shown for clarity). By repeating this operation over the entire range of the radiation beam (5), it is possible to generate a high-resolution calculated dose distribution map over the entire plane (X, Y) that is dispersed along the Z-axis and separated by a distance (tk) as shown in Figs. 1a and 5b.

[0072] In a preferred embodiment, rather than calculating the dose distribution over the entire plane (X, Y) for each position (k) independently of other positions ((k - 1), (k + 1), etc.), the calculated dose distribution within the plane (X, Y) at position (k) also takes into account the dose values measured by adjacent detectors (1k) at adjacent positions ((k - 1), (k + 1)). This can be achieved by ensuring that the function f(DAij, DICi) and / or D0j = g(DA0j, DICia, DAija) is at least a function of at least the following doses: ● The dose (DAija) measured by the corresponding sensor (Aija) at the positions ((k - 1); (k + 1)) that are directly adjacent to position (k), and / or ● The dose (DA0ja) measured by the corresponding sensor (A0ja) at positions ((k - 1); (k + 1)) that are directly adjacent to position (k).

[0073] This enables the acquisition of a smoother dose distribution (with no step or a small step between the calculated dose values (Dij, i ≧ 0) determined for various positions (k)) along the Z-axis.

[0074] Method for characterizing the dose measurement of a radiation beam (5) The present invention also relates to a method for characterizing the dose measurement of a radiation beam (5) propagating along the Z-axis, the method including the following: ● Placing the dose detector (1) perpendicular to the Z-axis as described above, ● Propagating the radiation beam (5) along the Z-axis across the dose detector (1), ● Measuring the dose (DICi) by the ionization detector (1IC) and the dose (DAij, i ≧ 0) by the additional detector (1A) of the dose detector (1), ● Calculating the calculated dose (Dij, i ≧ 0) according to the doses (DICi, DAij, DA0j) measured in this way.

[0075] The detector (1) is preferably placed in a phantom to form a dose measurement characterization unit as shown in Figure 2a to control the WET build-up corresponding to the position (k) of the detector (1) along the Z-axis. The detector (1) can be configured to change the position of the plane (X, Y) to form a 3D dose measurement characterization unit as shown in Figure 2c, or can be accompanied by adjacent dose measurement dose detectors (1.k) dispersed along the Z-axis to form a 3D dose measurement characterization unit as shown in Figure 2b.

[0076] The detector (1), dose measurement characterization unit, and method of the present invention enable the generation of reliable high-resolution dose measurement mapping required to ensure accurate QA not only associated with current radiotherapy but also with new evolutions in radiotherapy, including FLASH therapy and adaptive therapy. In the framework of PSQA, this detector enables very rapid determination of the dose distribution and significantly reduces the PSQA calculation time. This detector also has the advantage of improving a narrow range of PSQA. This is achieved by combining the high accuracy, precision, and reliability of the dose measurement values measured by the IC detector (1IC) with the high resolution obtained by additional detectors (1A) such as semiconductor detectors and scintillation detectors. The key point of the present invention is that when the advantages of the two types of detectors are added together, their disadvantages are not, and the disadvantages of one detector are compensated for by the advantages of the other. In this way, a synergistic effect is obtained, where the low spatial resolution of the IC detector (1IC) is compensated for by the high spatial resolution of the additional detector (1A), and the high energy dependence of the additional detector (1A) is compensated for by the high accuracy and precision of the values measured by the IC detector (1IC). Intelligence (10) is essential for combining the values measured by each detector (1IC, 1A) to yield a calculated dose distribution (Dij, i≥0) that represents reality.

[0077] # Definitions 1 Detector 1A Additional detector 1IC Ionization detector 1.k Nearest neighbor detector 3+, 3- Electrodes of the ionization chamber 3g Ionization gas of the ionization chamber 3V Voltmeter of the ionization chamber 5 Radiation beam 10 Intelligence A0j Sensor of the additional detector facing the inter-chamber space Aij, i>0 Sensor of the additional detector facing the ionization chamber ICi DA0j Dose measured by the sensor A0j DAij, i>0 Dose measured by the sensor Aij Average dose measured by sensor (Aij) facing ionization chamber (ICi) TIFF2025102716000009.tif5170 DICi Dose measured by ionization chamber ICi D0j Calculated dose in the intermediate unit volume Dij Calculated dose in the unit volume shielding ionization chamber ICi Dija Calculated dose in the unit volume adjacent to the intermediate unit volume i>0 Index of a given ionization chamber and index of the sensor facing the given ionization chamber j Index of the sensor k = 1~K Position of plane (X,Y) along the Z-axis t0x Ionization chamber-ionization chamber distance along the X-axis t0y Ionization chamber-ionization chamber distance along the Y-axis t1 Thickness of the dose detector along the Z-axis tA Thickness of the additional detector along the Z-axis tIC Thickness of the ionization detector along the Z-axis tICx Size of the ionization cell along the X-axis tICy Size of the ionization cell along the Y-axis tICz Thickness of the IC detector along the Z-axis tk Distance separating two adjacent measurement positions k X,Y,Z Reference axes

Claims

1. In a detector (1) for characterizing the measurement of the radiation dose, the detector (1) includes an ionization detector (1IC) configured to characterize the measurement of a radiation beam (5) propagating along the Z-axis, the ionization detector (1IC) includes a matrix of ionization chambers (ICi) distributed over the entire plane (X, Y) perpendicular to the Z-axis, each ionization chamber (ICi) includes first and second electrodes separated by a medium, and the ionization detector has a first spatial resolution over the entire plane (X, Y). In the detector (1), Unlike the ionization detector (1IC), an additional detector (1A) having a second spatial resolution over the entire plane (X, Y) finer than the first spatial resolution over the entire plane (X, Y) of the ionization detector is placed in series along the Z-axis with respect to the ionization detector (1IC), and the detector includes or is coupled to an intelligence (10) configured to calculate the distribution of the calculated dose (Dij) from the dose (Dici) measured by the ionization detector (1IC) and the doses (DAij, DA0j) measured by the additional detector (1A), Detector (1), characterized in that.

2. In the detector according to claim 1, the additional detector (1A) is selected from the group consisting of a semiconductor detector, a scintillation detector, a thermoluminescence detector, a film, a chemical detector including a polymer gel, and an alanine detector. Detector, characterized in that.

3. In the detector according to claim 1 or 2, the ionization detector (1IC) has a physical thickness (tIC) measured along the Z-axis, the additional detector (1A) has a physical thickness (tA) measured along the Z-axis, and one of the ionization detector and the additional detector having a physical thickness (tIC, tA) that results in a minimum water equivalent thickness (WET) for a given radiation is placed upstream along the Z-axis with respect to the radiation beam (5). Detector, characterized in that.

4. In the detector according to claim 2 or 3, ● the additional detector (1A) is a semiconductor detector placed upstream of the ionization detector (1IC) along the Z-axis with respect to the radiation beam (5), or ● the additional detector (1A) is a scintillation detector placed downstream of the ionization detector (1IC) along the Z-axis with respect to the radiation beam (5). A detector characterized by the following.

5. In the detector according to any one of Claims 1 to 4, the radiation beam (5) is a beam of charged particles (preferably protons, electrons, helium ions, carbon ions or oxygen ions), or an electromagnetic radiation (preferably photons, more preferably X-rays or γ-rays) beam, characterized detector.

6. In the detector according to any one of Claims 1 to 5, the detector (1) has a physical thickness (t1) measured along the Z-axis of less than 100 cm, characterized detector.

7. In the detector according to any one of claims 1 to 6, the distance (tIC-A) between the effective measurement point of the ionization detector (1IC) and the effective measurement point of the additional detector (1A) is 5 cm or less, preferably 5 g / cm ２ A detector characterized by corresponding to the following WET.

8. In the detector (1) according to any one of Claims 1 to 7, ● The ionization chambers (ICi) are distributed over the entire surface (X, Y) of the ionization detector (1IC), cm ２ with a resolution of at least 1 ionization chamber (IC) per cm, preferably cm ２ with a resolution of at least 1.5 ionization chambers (ICi) per ● The additional detector (1A) has a pixel resolution of at least twice the resolution of the ionization detector (1IC), A detector characterized by the following.

9. In the detector (1) according to any one of Claims 1 to 8, the intelligence (10) is also configured to determine the distribution of the linear energy transfer (LET) of the radiation from the measured dose (DICi, DAij, DA0j), characterized detector (1).

10. In the detector according to any one of Claims 1 to 9, ● Each ionization chamber (ICi) is separated from the adjacent ionization chamber of the same ionization detector (1IC) by an inter-chamber space (t0x, t0y), ● One or more sensors (Aij) of the additional detector face the ionization chamber (ICi) of the ionization detector (1IC), ● One or more sensors (A0j) of the additional detector face the inter-chamber space, ● The sensors (Aij, A0j) of the additional detector have a higher energy dependence than the ionization chamber (ICi) of the ionization detector (1IC), ● The calculated dose (Dij) in the unit volume enclosed in or intersecting the detector (1) at the level of the ionization chamber (ICi) is a function Dij = f(DAij, DICi) of the dose (DICi) measured by the ionization chamber (ICi) and the dose (DAij) measured by a given sensor (Aij) of the additional detector facing the ionization chamber (ICi) along the Z-axis. Preferably, the function Dij = f(DAij, DICi) also includes the following doses: ○ The dose (DICia) measured by the neighboring ionization chamber (ICia) adjacent to the unit volume, ○ The dose (DAija) measured by the neighboring sensor (Aija) of the additional detector (1A) facing the ionization chamber (ICi), preferably the sensor adjacent to the given sensor (Aij). ○ The dose (DA0ja) measured by the neighboring sensor (A0ja) of the additional detector (1A) facing the inter-box space adjacent to the unit volume. Depending on one or more of Detector, characterized by this.

11. In the detector according to claim 10, the calculated dose (Dij) depends on the dose (DICi) measured by the ionization chamber (ICi) and the dose (DAij) measured by the sensor (Aij) of the additional detector facing the ionization chamber (ICi) along the Z-axis, i.e., Dij = f(DAij, DICi, f1(DCAij)), and the sub-function f1(DICAij) is preferably the ratio (DICi / DAij) or difference (DICi - DAij) between the doses (DAij and DICi) measured by the additional detector (1A) and the ionization detector (1IC). Detector, characterized by this.

12. In the detector according to claim 10 or 11, ● At least one sensor (A0j) of the additional detector (1A) faces the inter-box space. ● The calculated dose (D0j) at the level of a given sensor (A0j) enclosed in an intermediate unit volume intersecting the detector (1) in the inter-box space between adjacent ionization chambers (ICia) is at least the following: ○ The dose (DA0j) measured by the given sensor (A0j) of the additional detector (1A), and one or more of the following: ○ The dose (DICia) measured by the neighboring ionization chamber (ICia) adjacent to the intermediate unit volume, and one or more of the following: ○ The dose (DA0ja) measured at least by the neighboring sensor (A0ja) of the additional detector (1A) enclosed in the same intermediate volume and adjacent to the given sensor (A0j), and ○ The dose (DAija) of the neighboring sensor (Aija) of the additional detector (1A) facing the neighboring ionization chamber (ICia). Is a function (D0j = g(DA0j, DICia, DAija)). Detector, characterized by this.

13. In a dose measurement characterization unit configured to characterize the dose measurement within the plane (X, Y) of a radiation beam that propagates over the entire Z-axis perpendicular to the plane (X, Y) at various positions (k = 1 to K, K>1) separated from each other by a distance (tk) along the Z-axis, the dose measurement characterization unit includes a detector (1) according to any one of claims 1 to 12 placed at the position (k), and ● further includes (K-1) adjacent detectors (1.k) (k + m; m≠0) according to any one of claims 1 to 12 aligned with the detector (1) arranged along the Z-axis and at each position, or ● the detector (1) is configured to be moved to various positions (k), whichever is the case. A dose measurement characterization unit characterized by this.

14. In the dose measurement characterization unit according to claim 13, the detector (1) and preferably the adjacent detector (1.k) are as described in any one of claims 10 to 12, and the functions Dij = f(DAij, DICi) and / or D0j = g(DA0j, DICia, DAija) determined at the position (k) are also as follows:[[]] ● the dose (DAija) measured by the corresponding sensor (Aija) at the positions ((k-1); (k+1)) directly adjacent to the position (k), and / or ● the dose (DA0ja) measured by the corresponding sensor (A0ja) at the positions ((k-1); (k+1)) directly adjacent to the position (k). A dose measurement characterization unit characterized by being one or more of the functions of.

15. In a method for characterizing the dose measurement of a radiation beam (5) propagating along the Z-axis,[[]] ● a step of placing the dose detector (1) according to any one of claims 1 to 12 perpendicular to the Z-axis; ● a step of propagating a radiation beam (5) along the Z-axis across the dose detector (1); ● a step of measuring the dose (DICi, DAij, DA0j) by the ionization detector (1IC) and the additional detector (1A) of the dose detector (1); ● a step of calculating the calculated dose (Dij, D0j) according to the dose (DICi, DAij, DA0j) measured in this way. A method characterized by including this.

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