Hybrid 2D detector

Abstract

The invention relates to a detector (1) for characterizing a dosimetry of radiation, comprising: an ionization detector (1IC) configured for characterizing a dosimetry of a radiation beam (5) propagating along a Z-axis, the ionization detector (1IC) comprising a matrix of ionization chambers (ICi) distributed over a plane (X, Y) perpendicular to the Z-axis, where the ionization detector (1IC) is located in the plane (X, Y); the ionization detector (1IC) has a first spatial resolution above the plane (X, Y), an additional detector (1A) distinct from the ionization detector (1IC) and whose second spatial resolution above the plane (X, Y) is higher than the first spatial resolution above the plane (X, Y) and is positioned in series with respect to the ionization detector (1IC) along the Z-axis, and a smart device (10), the smart device is configured to calculate a distribution of the calculated dose (Dij) from the dose (DICi) measured by the ionization detector (1IC) and the dose (DAij, DA0j) measured by the additional detector (1A).

Description

Field of the Invention

[0001] The present invention relates to the field of detectors for performing dosimetry of radiation (e.g., proton beam, electron beam, helium ion beam, carbon ion beam, or oxygen ion beam, or electromagnetic radiation beam such as X-ray or γ-ray beam). The detector of the present invention relies on the high accuracy and low beam energy dependence of the measurement results obtained through an ionization chamber, and has a spatial resolution significantly finer than that achievable by an ionization chamber. Background of the Invention

[0003] Radiotherapy is widely used to treat tumor cells in a patient's body. Different radiations can be considered, including proton beam, electron beam, helium ion beam, carbon ion beam, or oxygen ion beam, or electromagnetic radiation beam, such as a photon beam, preferably an X-ray or γ-ray beam. 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 a prescribed dose in a prescribed region.

[0004] 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 detector of the present invention is applicable to both machine quality assurance and patient-specific quality assurance, and is preferably but not exclusively applied to patient-specific quality assurance (PSQA). Quality assurance is needed to verify whether the treatment delivery corresponds to the dose calculated by the TPS. For example, PSQA typically includes measuring 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 dose measurements. The gamma evaluation method is widely used to compare such measurements. Currently, two other forms of PSQA are increasingly used clinically: logarithm-based QA and PSQA based on independent dose calculations by Monte Carlo simulation.

[0005] As Figure 2a shown, the 2D detector (1) is positioned across the path of the radiation beam (5) propagating along the Z-axis. The 2D detector (1) measures the dose distribution on a "slice" in the plane (X,Y) perpendicular to the Z-axis, as Figure 1b and Figure 2b shown. The 2D detector can be positioned in a phantom (7) that defines a water equivalent thickness (WET) corresponding to the equivalent depth in a patient. As Figure 2a , Figure 2c and Figure 2d shown, the phantom can be a tank filled with water or other liquid. It can also be made of a plate of a given material with a given thickness and known WET. The 2D detector can be positioned along the Z-axis by positioning several 2D detectors (as Figure 2c shown) or by moving the 2D detector (1) along the Z-axis (asFigure 2d as shown) to obtain a 3D dose distribution as shown in Figure 1a . Thus, the dose distribution over a number of slices is measured as shown in Figure 2e , and the dose distribution along the Z-axis can be obtained as shown in Figure 1c and Figure 2f .

[0006] It is known that there are various detectors for measuring the dose deposited by a given radiation at a given WET. One of the most widely used detectors is the ionization chamber detector (= IC detector) formed by an array of ionization chambers distributed on a plane (X,Y), such as described in EP1889281. As shown in Figure 6b and Figure 6c , an ionization chamber (ICi) consists of two polarization electrodes (3-, 3+) separated by a gap (3g) filled with a fluid, preferably a gas (usually air) or a liquid. The fluid is ionized by the radiation (5) passing through the ionization chamber (ICi), thus forming charged ions. An electric field is generated by an external voltage source applied between the two polarization electrodes (3-, 3+). The charged ions are collected by the electrodes, thus generating a measurable charge. For a given electric field applied to the ionization chamber and for a given design of the ionization chamber (including the width of the gap, the given dimensions of the electrodes (3-, 3+), etc.), dosimetric parameters including radiation dose and linear energy transfer (LET) distribution can be determined based on the amplitude of the charge measured by a measuring device (3V) (e.g., a voltmeter or an ammeter) at the electrodes (3-, 3+).

[0007] However, the ionization chamber provides a marginal spatial resolution on the order of mm (e.g., 5 to 8 mm), which severely limits the accuracy of the dose map established by the measurements of the IC detector. Increasing the spatial resolution of the ionization chamber array has proven to be very difficult because the signal-to-noise ratio deteriorates rapidly when the separation distance (t0x, t0y) between adjacent ionization chambers is reduced.

[0008] There are other detectors available on the market. For example, semiconductor-based 2D detectors are alternatives to IC detectors, offering significantly finer spatial resolution in the μm range (e.g., 10 to 300 μm). Semiconductor detectors are solid-state detectors that detect radiation and convert it into charge. This can be achieved using either direct conversion or indirect conversion. In direct conversion detectors, ionizing radiation directly generates electron-hole pairs in the semiconductor. Under the influence of an electric field, the free electrons and holes travel to the electrodes, where the current can be measured. Indirect conversion detectors include scintillation detectors, which consist of a scintillation layer that converts ionizing radiation into photons, and these photons are then converted into charge by a photodetector. Some semiconductor-based detectors can also be used to quantify the linear energy transfer (LET) of particles. Thermoluminescent detectors are another type of indirect conversion detector.

[0009] However, the values measured with both direct conversion semiconductor detectors and indirect conversion semiconductor detectors exhibit high energy dependence and may "quench" when exposed to particle radiation. Although the mechanism of ionization quenching is not fully understood, the result is that the detector's response deviates from the actual dose in regions with "high" linear energy transfer values. As Figure 1c shown, this is the case, for example, in the Bragg peak region of a clinical proton beam (compare the fine dashed Bragg peak measured using an ionization chamber with the thick dashed line measured using a quenched semiconductor detector in Figure 1c ).

[0010] Next, direct conversion detectors are referred to as "semiconductor detectors", and indirect conversion detectors are referred to as "scintillation detectors" or "thermoluminescent detectors".

[0011] A new generation of dosimetry detectors dedicated to PSQA needs to be developed. This new generation of detectors should give a fast and accurate response with high spatial resolution under different conditions, including conventional dose rates and doses, as well as ultra-high dose rates and high doses (also known as FLASH) irradiation, different types of particles, different delivery modes (scattered beam, scanned pencil beam), different beam time structures (pulsed beam, continuous beam), etc.

[0012] The present invention proposes a detector for dosimetry of characterizing radiation, which combines high accuracy, high precision, and high spatial resolution and enables the measured values to have significantly lower energy dependence. These and other advantages of the present invention are described in more detail in the following sections. SUMMARY OF THE INVENTION

[0013] The present invention relates to a detector for dosimetry of radiation characterization, the detector comprising an ionization detector configured for dosimetry of a radiation beam propagating along the Z-axis. The radiation beam can be a charged particle beam, preferably a proton beam, an electron beam, a helium ion beam, a carbon ion beam or an oxygen ion beam, or can be an electromagnetic radiation beam, preferably a photon beam, more preferably an X-ray or a gamma ray beam.

[0014] The ionization detector comprises a matrix of ionization chambers distributed over a plane (X, Y) perpendicular to the Z-axis. Each ionization chamber comprises a first electrode and a second electrode separated by a dielectric, wherein the ionization detector has a first spatial resolution over the plane (X, Y).

[0015] An additional detector (1A), different from the ionization detector and having a second spatial resolution over the plane (X, Y) that is finer than the first spatial resolution of the ionization detector over the plane (X, Y), is positioned in series along the Z-axis relative to the ionization detector. The detector comprises or is coupled to an intelligent device configured to calculate the distribution of the calculated dose based on the dose measured by the ionization detector and the dose measured by the additional detector.

[0016] The additional detector can be selected from the group consisting of: semiconductor detectors, scintillation detectors, thermoluminescent detectors, chemical detectors, wherein the chemical detectors comprise thin films, 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 the thickness that produces the lowest water equivalent thickness (WET) for a given radiation is preferably positioned upstream along the Z-axis relative to the radiation beam. For example, the additional detector can be a semiconductor detector positioned upstream of the ionization detector along the Z-axis relative to the radiation beam. Alternatively, the additional detector can be a scintillation detector positioned downstream of the ionization detector along the Z-axis relative to the radiation beam.

[0018] The detector has a thickness (t1) measured along the Z-axis, which 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. A detector (1) having a physical thickness (t1) within the upper limit range may include, for example, a scintillator detector as an additional detector (1A), which includes a thin scintillation plate, but also requires an optical structure (including, for example, mirrors and a photodetector such as a camera (e.g., a CCD camera)), which significantly increases the thickness (1A,t1) of the additional detector (1A) and thus increases the thickness of 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 not greater than 5 cm, preferably not greater than 2 cm. In some embodiments, the IC detector (1IC) and the additional detector (1A) can even be in contact with each other, thus reducing the distance to close to 0 (i.e., tIC-A→0). Preferably, the thickness (t1) of the detector (1) corresponds to a WET of not more than 5 g / cm 2 of the WET.

[0019] In a preferred embodiment, ionization chambers are distributed over the plane (X,Y) of the ionization detector, and the resolution of the ionization detector is per cm 2 at least one ionization chamber (IC), preferably per cm 2 at least 1.5 ionization chambers (ICi). Preferably, the pixel resolution of the additional detector is at least twice the resolution of the ionization detector. The resolution of the additional detector can be at least 50 pixels / cm 2 or at least 70 pixels / cm 2 or at least 100 pixels / cm 2 .

[0020] The intelligent device is preferably configured to determine the distribution of the linear energy transfer (LET) of the radiation based on the measured dose.

[0021] In a preferred embodiment, each ionization chamber is separated from an adjacent ionization chamber of the same ionization detector by an inter-chamber space. One or more sensors (Aij) of the additional detector face the ionization chambers 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 chambers of the ionization detector. The calculated dose Dij in the unit volume surrounded or intersecting the detector at the ionization chamber level 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:

[0022] · The dose DICia measured by an adjacent ionization chamber adjacent to the unit volume,

[0023] · The dose DAija measured by adjacent sensors of the additional detector facing the ionization chamber and preferably those sensors adjacent to the given sensor, and

[0024] · The dose DA0ja measured by adjacent sensors of the additional detector facing the inter-chamber space adjacent to the unit volume.

[0025] The calculated dose Dij can depend on a sub-function f1(DICAij) that correlates the dose (DICi) measured by the ionization chamber with the dose (DAij) measured by the sensor of the additional detector facing the ionization chamber along the Z-axis (i.e., Dij = f(DAij, DICi, f1(DCAij))). The sub-function f1(DICAij) is preferably the ratio (DICi / DAij) or the difference (DICi – DAij) between the doses (DAij and DICi) measured by the additional detector and the ionization detector.

[0026] In a preferred embodiment, at least one sensor of the additional detector faces the inter-chamber space. The dose (D0j) calculated at the level of a given sensor surrounded in an intermediate unit volume intersecting the detector at the inter-chamber space between adjacent ionization chambers is a function D0j = g(DA0j, DICia, DAija) of at least the following:

[0027] · The dose (DA0j) measured by the given sensor of the additional detector, and one or more of the following:

[0028] · The dose (DICia) measured by an adjacent ionization chamber adjacent to the intermediate unit volume, and one or more of the following:

[0029] · The dose (DA0ja) measured by at least adjacent sensors of the additional detector that are enclosed in the same intermediate volume and adjacent to a given sensor, and

[0030] · The dose (DAija, i > 0) of the adjacent sensor of the additional detector facing the adjacent ionization chamber.

[0031] The present invention also relates to a dosimetry characterization unit configured to characterize the dosimetry on the plane (X, Y) at different positions (k = 1 to K, where K > 1) separated from each other by a certain distance (tk) along the Z-axis of a radiation beam propagating above the Z-axis perpendicular to the plane (X, Y). The dosimetry characterization unit includes a detector as described above, which is positioned at the position (k); and

[0032] · Further, the dosimetry characterization unit includes (K - 1) adjacent detectors as described above, which are aligned with the detector along the Z-axis and are located at the corresponding positions (k + m; m ≠ 0), or

[0033] · The detector is configured to move to different positions.

[0034] In a preferred embodiment, the detector and preferably the adjacent detectors are as described above, wherein the calculated dose (Dij, D0j) in the unit volume enclosed or intersected by the detector at the level of the ionization chamber (ICi) is the function Dij = f(DAij, DICi), and preferably the function D0j = g(DA0j, DICia, DAija). The function Dij = f(DAij, DICi) and / or D0j = g(DA0j, DICia, DAija) determined at the position (k) is also a function of one or more of the following:

[0035] · The dose (DAija) measured by the corresponding sensors at the positions ((k - 1); (k + 1)) directly adjacent to the position (k), and / or

[0036] · The dose (DA0ja) measured by the corresponding sensors at the positions ((k - 1); (k + 1)) directly adjacent to the position (k).

[0037] The present invention also relates to a method for characterizing the dosimetry of a radiation beam propagating along the Z-axis, the method comprising:

[0038] · Positioning a dose detector as described above perpendicular to the Z-axis,

[0039] · Propagating the radiation beam along the Z-axis through the dose detector,

[0040] · Measuring the doses (DICi, DAij, DA0j) using the ionization detector and the additional detector of the dose detector.

[0041] · Calculating the calculated doses (Dij, D0j) based on the doses (DICi, DAij, DA0j) measured as such. Description of the Drawings

[0042] These and further aspects of the invention will be explained in more detail by way of example and with reference to the drawings, in which:

[0043] Figure 1a A 3D representation of the dose deposition in the plane (Y, Z) is shown, with a typical Bragg peak of the proton beam dose deposition.

[0044] Figure 1b Shows at the level of the Bragg peak of Figure 1a The 2D dose deposition on the Y-axis perpendicular to the Z-axis measured using an ionization chamber array (= thin dashed line) and a semiconductor detector (thick dashed line). The shaded columns represent the positions of the various ionization chambers (ICi), where i = 1 to I.

[0045] Figure 1c Shows the 2D dose deposition on the Z-axis measured by a series of detectors with an ionization chamber array (= thin dashed line) and a semiconductor detector (thin dashed line) positioned along the Z-axis. The shaded columns represent the positions of the various detectors, where k = 1 to K.

[0046] Figure 2a Shows a detector positioned in the phantom and intersecting the trajectory of the radiation beam.

[0047] Figure 2b Shows by Figure 2a The dose distribution along the Y-axis measured by the detector of

[0048] Figure 2c Shows a series of detectors intercepting the radiation beam aligned along the Z-axis in the phantom.

[0049] Figure 2d Shows a detector positioned movably along the Z-axis in the phantom and intersecting the trajectory of the radiation beam.

[0050] Figure 2e Shows by Figure 2c Measured by the three detectors of Figure 2d Or the dose distribution along the Y-axis measured by the detector of Figure 2d At three different positions.

[0051] Figure 2f Plots Figure 2eThe functional relationships of the doses Dij.(k - 1), Dij.k, and Dij.(k + 1) of the dose distribution with the position of the detector along the Z-axis.

[0052] Figure 3a and Figure 3b Shows (a) a series of additional (semiconductor) detectors and (b) the corresponding proton beam 3D dose deposition curves obtained therefrom, where the quenching effect is visible through the short and wide geometry of the Bragg peak.

[0053] Figure 4a and Figure 4b Shows (a) a series of ionization chamber detectors and (b) the corresponding proton beam 3D dose deposition curves obtained therefrom, which have a low spatial resolution as shown by the shaded squares.

[0054] Figure 5a and Figure 5b Shows (a) a series of detectors formed by connecting in series the additional detectors in Figure 3a with the ionization chamber detectors in Figure 4a according to the present invention, and (b) the corresponding proton beam 3D dose deposition curves obtained by using them, which combine accuracy and high spatial resolution.

[0055] Figure 6a Shows a detector formed by connecting in series the semiconductor detectors in Figure 3a with the ionization chamber detectors in Figure 4a according to the present invention.

[0056] Figure 6b and Figure 6c Shows two embodiments of the ionization chamber.

[0057] Figure 6d Shows a front view (in the plane (X, Y)) of the detector according to the present invention, which shows the alignment of the sensors (Aij, A0j) relative to the ionization chamber (ICi).

[0058] Figure 7a Shows a comparison of the deposited dose (DICi) measured by a single ionization chamber (ICi) with the deposited dose (DAij) measured by a semiconductor facing the single ionization chamber along the Z-axis, where the latter shows the quenching effect and has a value lower than that measured by the ionization chamber.

[0059] Figure 7b Shows the deposited dose (Dij) calculated according to the present invention based on the combination of the single value measured by the ionization chamber as shown in Figure 7a and the value measured by the semiconductor detector.

[0060] Figure 8aShows a comparison of three deposited doses (DICi) measured by three ionization chambers (ICi) with the deposited doses (DAij) measured by a semiconductor facing each of the three ionization chambers along the Z-axis and the deposited doses (DA0j) measured by a semiconductor facing the intermediate volume between adjacent ionization chambers.

[0061] Figure 8b Shows the deposited dose (Dij) calculated according to the present invention based on the combination of three values measured by three ionization chambers as Figure 8a shown and the values measured by a semiconductor detector.

[0062] Figure 9a Shows the relationship between various ionization chambers (ICi) of an IC detector (1IC) and sensors (Aij, i>0) of an additional detector (1A) facing the ionization chambers (ICi), where an intelligent device (10) is used to calculate the calculated dose (Dij) corresponding to a given sensor (Aij, i>0).

[0063] Figure 9b Shows the relationship between a sensor (A0) of the additional detector (1A) facing the inter-chamber space and adjacent ionization chambers (ICi) of the IC detector (1IC), where an intelligent device (10) is used to calculate the calculated dose ((Dij) corresponding to a given sensor (A0j). Detailed Description

[0064] As Figure 6a shown, a detector (1) for dosimetry for characterizing a radiation beam (5) according to the present invention includes an ionization detector (1IC) and an additional detector (1A) aligned along the Z-axis, both being configured for dosimetry for characterizing a radiation beam (5) propagating along the Z-axis. The radiation beam (5) can be a charged particle beam, preferably a proton beam, an electron beam, a helium ion beam, a carbon ion beam or an oxygen ion beam, or an electromagnetic radiation beam, preferably a photon beam, preferably an X-ray or γ-ray beam.

[0065] The ionization detector (1IC) includes a matrix of ionization chambers (ICi) distributed over a plane (X,Y) perpendicular to the Z-axis. As Figure 6b and Figure 6c shown, each ionization chamber (Ici) includes a first electrode and a second electrode (3-, 3+) separated by a dielectric (preferably a gas (such as air) or a liquid). The ionization detector has a first spatial resolution over the plane (X,Y).

[0066] The additional detector (1A) is different from the ionization detector (1IC) and has a second spatial resolution above the plane (X, Y) that is finer than the first spatial resolution of the ionization detector (Ici) above the plane (X, Y). The additional detector is positioned in series relative to the ionization detector (1IC) along the Z-axis.

[0067] The detector further comprises or is coupled to a smart device configured to calculate the distribution of the calculated dose (Dij) based on the dose (DICi) measured by the ionization detector (1IC) and the doses (Daij, DA0j) measured by the additional detector (1A).

[0068] Detector configuration for quality assurance

[0069] As Figure 1b 、 Figure 2a and Figure 2b shown, the detector (1) according to the invention for quality assurance, preferably for PSQA, is a 2D detector configured to characterize the dosimetry of a radiation beam (5) propagating along the Z-axis in a plane (X, Y) perpendicular to the radiation beam. The plane (X, Y) in the patient's body at the desired depth can be simulated by positioning the detector (1) in a phantom (7) at the corresponding water equivalent thickness (WET). The phantom is typically formed by a water-filled tank. It can also be filled with different liquids, or the phantom can be formed by a solid plate of known WET and given thickness. Thus, the detector (1) is positioned at the strategy depth or WET of interest. For example, for a proton beam, the plane (X, Y) preferably intercepts the Bragg curve.

[0070] As Figure 1a 、 Figure 1c and Figures 2c to 2f shown, a 3D dose distribution map can be obtained by combining the dose distributions on various planes (X, Y) distributed along the Z-axis. This can be achieved by aligning a plurality of detectors (1) along the Z-axis or by moving a single detector along the Z-axis (e.g., along an orbit as Figure 2c shown) using a dosimetry characterization unit as Figure 2d shown.

[0071] However, the detector configurations shown above and Figures 2a to 2f require the detectors used to exhibit a sufficiently high spatial resolution and a sufficiently high accuracy, precision, and reliability. In particular, the values measured using the detector should not depend on quenching effects. However, as discussed in the "Background of the Invention" section above, the currently available ionization chamber-based detectors on the market do not satisfy this combination satisfactorily. This is achieved using the detector (1) of the present invention, which comprises an ionization detector (1IC) and an additional detector (1A) aligned in series along the Z-axis.

[0072] Ionization detector (1IC)

[0073] As Figure 4a and Figure 6a shown, the ionization detector (=IC detector) is formed by an array of ionization chambers (ICi) distributed on a plane (X,Y). The ionization chamber (ICi) includes a first electrode and a second electrode (3−, 3+) separated by a dielectric (preferably a gas (such as air) or a liquid). As Figure 6b and Figure 6c shown, the electrodes (3−, 3+) can be flat electrodes parallel to each other, or can be concentric cylindrical electrodes as Figure 6b and Figure 6c shown. The measuring unit (3V) (such as an electrometer) measures the current generated between the electrodes by the ionized molecules of the dielectric through which the radiation beam (5) passes.

[0074] Each ionization unit (ICi) has a width (tICy) and a height (tICx) measured along the Y-axis and the X-axis respectively (see Figure 6a and Figure 6d ). The physical thickness of each ionization unit (ICi) along the Z-axis is less important than its WET. Preferably, the WET of the ionization unit is as low as possible, i.e., preferably, the radiation beam (5) loses as little energy as possible when passing through the ionization chamber (ICi). This is particularly important if the ionization detector (1IC) is located upstream of an additional detector (1A). This is also important in the case where a number of detectors (1.k) are aligned in series along the Z-axis as Figure 2c shown to establish a 3D dose deposition map of the radiation beam (5).

[0075] The ionization chambers (ICi) are separated from each other by a distance (t0x, t0y) along the X-axis and the Y-axis respectively. The spatial resolution of the IC detector (1IC) depends on the size (tICx, tICy) of the ionization chambers (ICi) on the one hand, and on the separation distance (t0x, t0y) between adjacent IC chambers (ICi) on the other hand. The response of the ionization chamber must be corrected for well-known effects (temperature, pressure, polarity, recombination) in a manner well-known to those skilled in the art. The size of the ionization chamber (ICi) is physically and technically limited. The rapid decrease in the signal-to-noise ratio limits the reduction of the separation distance (t0x, t0y) between adjacent ionization chambers. Therefore, the spatial resolution of the IC detector (1IC) is limited and cannot be increased significantly at present. Preferably, the ionization chambers (ICi) are distributed on the plane (X,Y) of the ionization detector (1IC), and the resolution of this ionization detector is at least one ionization chamber (IC), preferably per cm 2 at least one ionization chamber (IC), preferably per cm 2At least 1.5 ionization chambers (ICi). It is also preferred that the pixel resolution of the additional detector (1A) is at least twice the resolution of the ionization detector (1IC).

[0076] However, the values (DICi) measured by the IC detectors (1IC, 1IC.k) are very reliable and insensitive to quenching. Figure 4a A series of IC detectors (1IC) are shown that are vertically distributed along the Z-axis and intersect the radiation beam (5). Figure 4b Shown by Figure 4a The dose values measured by various IC detectors aligned along the Z-axis, which are obtained by combining the dose values measured by each IC detector (1IC) in a series of IC detectors of Figure 3a at the same position along the X-axis. The values measured by each ionization cell (ICi) of each IC detector (1IC) intersecting the (Y,Z) plane are represented by shaded squares distributed on the (Y,Z) plane on the expected Bragg curve, and its thickness (tICz) is measured along the Z-axis. It can be seen that the dose values (DICi) measured by each ionization cell (ICi) conform to the expected beam shape in each (X,Y) plane, as Figure 1b shown (thin dashed line), but the spatial resolution is not sufficient to satisfactorily characterize the beam. The IC detector (1IC) has a first spatial resolution on the order of mm (e.g., 5 to 8 mm) above the plane (X,Y).

[0077] Additional detector (1A)

[0078] The additional detector (1A) must be different from the IC detector (1IC) and its second spatial resolution above the plane (X,Y) must be finer than the first spatial resolution of the IC detector (1IC) above the plane (X,Y). The pixel resolution of the additional detector (1A) is preferably at least twice the resolution of the ionization detector (1IC). For example, the resolution of the additional detector (1A) can be at least 50 pixels / cm 2 , preferably at least 100 pixels / cm 2 .

[0079] The additional detector (1A) can be selected from the group consisting of: semiconductor detectors, scintillation detectors, thermoluminescent detectors, chemical detectors, where the chemical detector includes thin films, polymer gels, and alanine detectors. The additional detector (1A) is preferably a semiconductor detector or a scintillation detector.

[0080] Figure 3aShows an example of a series of additional detectors (1A, 1A.k) aligned along the Z-axis and perpendicular thereto and through which a radiation beam (5) passes. Each additional detector (1A) is formed by an array of sensors (Aij, A0j) distributed over a corresponding plane (X,Y). As Figure 6d can be seen, the size of the sensors (Aij, A0j) is substantially smaller than the size of the ionization chambers (ICi) of the IC detector (1IC), and the distance by which the sensors of the additional detector are separated from each other is substantially smaller than the ionization chambers (ICi) of the IC detector (1IC). This results in a substantially denser sensor array, thereby increasing the spatial resolution accordingly. However, many additional detectors (1A), including semiconductor detectors, are sensitive to quenching when traversed by a high-energy particle radiation beam (5). For example, this may be the case in the region of the Bragg peak of a proton beam. In Figure 3a the illustrated embodiment, the additional detector (1A) is a semiconductor detector and the sensors (Aij, A0j) are semiconductors.

[0081] A scintillation detector includes an array of scintillation layers. In response to an incident radiation beam (5), each scintillation layer produces photons in an amount depending on the dose deposited by the radiation beam. These are collected by photodetectors (e.g., cameras) which convert the light energy into electrical energy whose amplitude can be measured.

[0082] Figure 3b Shows the dose distribution above the plane (Y,Z) obtained by combining the dose values measured at the same position along the X-axis by each semiconductor detector (1A) of the Figure 3a series of semiconductor detectors. Different from the IC detector results plotted in Figure 4b , the spatial resolution of the dose distribution measured by the semiconductor (additional) detectors (1A, 1A.k) plotted in Figure 3b and measured with Figure 3a is higher, where the second spatial resolution is on the order of μm (e.g., 10 to 300 μm). However, the absolute values (DAij, DA0j) obtained with the Figure 3a additional detectors are unreliable because quenching effects are observed at high energies where the Bragg peak has a flattened geometry.

[0083] Figure 1b , Figure 3b and Figure 4b show that neither the IC detector (1IC) nor the additional detector (1A) (e.g., semiconductor detector) satisfactorily characterizes the dosimetry of the radiation beam (5), either having poor spatial resolution or poor reliability of the results at high-energy particle beams. The detector (1) of the present invention solves this problem by combining the advantages of the two detectors and compensating for their respective disadvantages.

[0084] The detector (1) of the present invention = a combination of an IC detector (1IC) and an additional detector (1A)

[0085] Since all existing detectors have advantages but also have unsatisfactory disadvantages, the present invention combines the advantages of different detectors to reduce and even offset their corresponding disadvantages. The detector (1) of the present invention includes an IC detector (1IC) having a first spatial resolution, wherein the additional detector (1A) is positioned in series along the Z-axis and has a second spatial resolution finer than the first spatial resolution. Figure 6a An example of the detector (1) according to the present invention is shown, which includes an IC detector (1IC) and an additional detector (1A). In this embodiment, the additional detector is a semiconductor detector. The two detectors (1IC, 1A) are coupled in series along the Z-axis and are separated from each other by a distance (tIC-A). For example, 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 preferably not greater than 5 cm, preferably corresponding to a WET of not greater than 5 g / cm 2 of the WET.

[0086] The additional detector (1A) has a physical thickness (tA), and the IC detector (1IC) has a physical thickness (tIC), such that the detector has a physical thickness (t1) measured along the Z-axis, t1 = tIC + tA + (tIC-A). For example, the detector (1) may have a physical thickness (t1) measured along the Z-axis of less than 100 cm, as described above.

[0087] The detector in the IC detector (1IC) and the additional detector (1A) having the physical thickness (tIC, tA) that produces the lowest water equivalent thickness (WET) for a given radiation is preferably positioned upstream along the Z-axis with respect to the radiation beam (5), because this detector has the lowest energy absorption effect on the radiation beam before the passing radiation beam (5) reaches the second detector positioned downstream. For example, as Figure 6a shown, the additional detector (1A) can be a semiconductor detector positioned 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 positioned 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.

[0088] The detector (1) of the present invention measures the dose (DICi) using an IC detector (1IC) and measures the doses (DAij, DA0j) using an additional detector (1A). The dose (DAij) is measured by a sensor (Aij) facing the corresponding ionization unit (ICi) of the IC detector (1IC), and the dose (DA0j) is measured by a sensor (A0j) facing the inter-chamber space of the neighboring ionization unit (ICi) that separates the IC detector (1IC). Figure 6d The front view of the detector (1) shows the positions of the sensors (Aij, A0j) of the additional detector (1A) relative to the ionization chambers (ICi) of the IC detector (1IC). The intelligent device (10) collects and uses the dose values (DICi, DAij, DA0j) measured by the IC detector (1IC) and the additional detector (1A) that form the detector (1) of the present invention to determine the calculated dose distribution (Dij, D0j) with the accuracy, precision, and reliability of the IC detector and the second spatial resolution of the additional detector (1A).

[0089] Figure 5b It shows the calculated dose distribution above the plane (Y,Z) measured by a series of detectors (1, 1.k) as shown in Figure 5a and calculated by the intelligent device (10). The detector (1) is formed by an IC detector (1IC) as shown in Figure 4a and a semiconductor detector aligned upstream with it as shown in Figure 3a . The calculated dose distribution (Dij = f(DAij, DA0j, DICi)) shown in Figure 5b characterizes the Bragg curve of the proton beam (5) with high reliability, precision, accuracy, and high spatial resolution Figure 5a . The intelligent device (10) is also preferably configured to calculate other dosimetric parameters, such as the distribution of the linear energy transfer (LET) of the radiation, based on the measured doses (DICi, DAij, DA0j).

[0090] The intelligent device (10) and the calculated dose distribution (Dij)

[0091] As shown in Figure 5a and Figure 6a , the detector (1) of the present invention includes or is coupled to an intelligent device (10), represented as a laptop computer in the figure, but it 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 intelligent device (10) is configured to calculate the distribution of the calculated doses (Dij, D0j) based on the dose (DICi) measured by the ionization detector (1IC) and the doses (DAij, DA0j) measured by the additional detector (1A).

[0092] As Figure 6d and Figure 9a shown, at least one, preferably more than one, sensor (Aij) of the additional detector (1A) faces the ionization chamber (ICi), and at least one, preferably more than one, sensor (A0j) of the additional detector (1A) faces the inter-chamber space. Thus, the number of sensors (Aij, A0j) of the additional detector (1A) is higher than the number of ionization chambers (ICi) of the IC detector, thereby endowing the additional detector with a second spatial resolution that is finer than the first spatial resolution of the IC detector.

[0093] The sensors (Aij) are the same as the sensors (A0j), and the different naming only refers to their positions relative to the ionization chamber (ICi). The index "i" indicates the corresponding ionization chamber (ICi) that the sensor (Aij) faces, and the index "0" indicates that the sensor faces the inter-chamber space. The index "j" counts the sensors according to their positions relative to the ionization chamber (ICi). For example, in Figure 6d , four sensors (Aij) face each ionization chamber (ICi), which are numbered Ai1, Ai2, Ai3, Ai4 (for clarity, Figure 6d not all sensors are labeled in

[0094] · ICi, DICi refers to the i-th ionization chamber and the dose measured using it. The index "i" in ICi and DICi is never equal to zero, that is, when referring to ICi and DICi, necessarily i > 0, and there is no need to specify it.

[0095] · Aij, DAij (where i ≥ 0) refers to all sensors of the additional detector (1A) and the dose measured using it, where,

[0096] ○ The sensor Aij with i > 0 faces the corresponding ionization chamber (ICi), and

[0097] ○ The sensor Aij with i = 0 faces the inter-chamber space.

[0098] 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).

[0099] · Dij (where i ≥ 0) refers to the calculated dose calculated based on the values of DICi and DAij, where,

[0100] ○For \(i > 0\), \(D_{ij}\) refers to the value calculated based on the dose measured by sensor \(A_{ij}\) where \(i > 0\), and

[0101] ○For \(i = 0\), \(D_{ij}\) refers to the value calculated based on the dose measured by sensor \(A_{ij}\) where \(i = 0\).

[0102] Therefore, when referring to \(D_{ij}\), it is necessary to specify whether \(i>0\) (indicating that \(D_{ij}\) is calculated for sensor \(A_{ij}\) where \(i > 0\) (i.e., excluding \(A_{0j}\))) or \(i\geq0\) (thus indicating that \(D_{ij}\) is calculated for sensor \(A_{ij}\) where \(i\geq0\) (i.e., all sensors including \(A_{0j}\))).

[0103] The sensors \((A_{ij}, i\geq0)\) of the additional detector have a higher energy dependence than the ionization chambers \((IC_i)\) of the ionization detector \((1IC)\), and thus cannot be safely used alone to determine the dose, because in the case where the additional detector \((1A)\) is quenched due to exposure to a radiation beam \((5)\) with too high energy, the values measured using it are not completely reliable.

[0104] Determination of the calculated dose \(D_{ij}(i > 0)\)

[0105] The calculated dose \((D_{ij}, i > 0)\) in the unit volume intersecting the detector \((1)\) at the level of the ionization chamber \((IC_i)\) can be a function \(D_{ij}=f(D_{Aij},D_{ICi})\) of the dose \((D_{ICi})\) measured by the ionization chamber \((IC_i)\) and the dose \((D_{Aij}, i > 0)\) measured by a given sensor \((A_{ij}, i > 0)\) of the additional detector \((1A)\) facing the ionization chamber \((IC_i)\) along the Z - axis, where \(i > 0\). This is shown in Figure 7a and Figure 7b shown. Figure 7a Shows the single dose \((D_{ICi})\) of the ionization chamber \((IC_i)\) over the area of the ionization chamber \((IC_i)\) in the plane \((X,Y)\) measured by one ionization chamber \((IC_i)\). Figure 7a Also shows the various dose values \((D_{Aij}\) where \(i > 0)\) measured by the sensors \((A_{ij}, i > 0)\) facing the ionization chamber \((IC_i)\). It can be seen that the additional detector \((1A)\) has a higher spatial resolution than the IC detector \((1IC)\). However, the dose values \((D_{Aij}, i > 0)\) measured by the sensors \((A_{ij}, i > 0)\) of the additional detector \((1A)\) are lower than the single value \((D_{ICi})\) measured by the ionization chamber \((IC_i)\) of the IC detector \((1IC)\), which indicates that the additional detector \((1A)\) suffers from a quenching effect, making the dose values \((D_{Aij}, i > 0)\) unreliable.

[0106] Figure 7bIt is shown that by using the calculated dose (Dij, i>0), the characterization of the dose distribution over the area of the ionization chamber (ICi) can have accuracy, precision, and high spatial resolution. The calculated dose is obtained by calculating the dose (Dij, i>0) based on the dose (DAij, i>0) measured by the additional detector (1A), and the dose measured by the additional detector is corrected to conform to the dose (DICi) measured by the IC detector (1IC).

[0107] The function f(DICi, DAij) for determining the value of the calculated dose (Dij, i>0) can take various forms, and the present invention is not limited to a single function. It is necessary 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) can depend on the sub-function f1(DICAij), which correlates the dose (DICi) measured by the ionization chamber (ICi) with 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)), where 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).

[0108] For example and as Figure 7a and Figure 7b shown, the function f1(DCAij) can be the difference between the dose (DICi) measured by the ionization chamber (ICi) and the average dose ( i>0) measured by the sensor (Aij, i>0) of the additional detector (1A) facing the ionization chamber (ICi). where i>0). Then, the calculated dose (Dij) can be where i>0. Using the average dose ( i>0) measured by the sensor (Aij, i>0) of the additional detector (1A) facing the ionization chamber (ICi) makes sense because the single dose value (DICi) measured by the ionization chamber (ICi) is the average value over the area (tICx × tICy) of the ionization unit (ICi).

[0109] Obviously, if no quenching occurs on the additional detector (1A) during the QA measurement, the sub-function f1(DAICij) = 0 and there is no need to correct the values (DAij, i≥0) measured by the sensors (Aij, i≥0) of the additional detector (1A).

[0110] 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 ( i>0) measured by the sensor (Aij, i>0) of the additional detector (1A) facing the ionization chamber (ICi) ( where i>0). Then, the calculated dose (Dij, i>0) can be expressed as where i>0. Other forms of the functions f(Aij,DICi,f1(DCAij)) and f1(DCAij) are of course possible, and these forms are entirely within the capabilities and scope of those skilled in the art.

[0111] In Figure 9a the preferred embodiment shown, the calculated dose (Dij, i>0) also depends on one or more of the following measured doses,

[0112] · the dose (DICia) measured by the ionization chamber (ICia) adjacent to the unit volume, and / or

[0113] · the dose (DAija, i≥0) measured by the sensor (Aija, i≥0) of the additional detector (1A) adjacent to the given sensor (Aij), including,

[0114] ○ the dose (DAija, i>0) measured by the adjacent sensor (Aija, i>0) facing the ionization chamber (ICi), preferably at least by the adjacent sensor directly adjacent to the given sensor (Aij), and / or

[0115] ○ the dose (DA0ja) measured by the adjacent sensor (A0j) facing the inter-chamber space adjacent to the unit volume.

[0116] Taking into account the doses (DAija, DICia) measured by the adjacent sensors (Aija) and / or adjacent ionization chambers (ICia) allows for generating a continuous, preferably smooth, dose distribution curve in the plane (X,Y). For example, under the condition that there is a continuous derivative between the calculated dose (Dij) emitted from a given sensor (Aij) and the calculated doses (Dija) emitted from the adjacent sensors (Aija) and adjacent ionization chambers (ICia).

[0117] Obviously, the function f1(DCAij) can also be applied when considering the dose (DICia) measured by the adjacent ionization chamber (ICi) and / or the dose (DAij, i≥0) measured by the adjacent sensors (Aij, i≥0) of the additional detector (1A).

[0118] Figure 8a and Figure 8b Schematically shows the determination of the calculated dose (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 sensor (Aij), the calculated dose (Dij) also takes into account the following:

[0119] · 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

[0120] · The dose (DAija, i≥0), including the doses (DAij, DAi(j + 1), DA(i + 1)j, DAi(i + 1)(j + 1), DA0j, DA0(j + 1), etc.) measured by the adjacent sensors (Aija, i≥0) including sensors (Aij, Ai(j + 1)j, A(i + 1)j, Ai(i + 1)(j + 1), A0j, A0(j + 1), etc.) (not shown).

[0121] Taking into account the signals of the adjacent sensors (Aija) and / or adjacent ionization chambers (ICia) in the determination of the calculated value of the dose (Dij) ensures that the calculated dose distribution above the plane (X,Y) is continuous and preferably smooth.

[0122] Determination of the calculated dose D0j

[0123] The determination of the calculated dose (D0j) in the intermediate unit volume where the plane of the inter - chamber space intersects the detector (1) between the adjacent ionization chambers (ICia) adjacent to the inter - chamber space can be carried out 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.

[0124] In a preferred embodiment, the calculated dose (D0j) in the intermediate unit volume is determined as follows. First, the additional detector (1) must include at least one, preferably more than one, sensor (A0j) facing the inter - chamber space of the IC detector (1IC). As Figure 9bAs shown, the calculated dose (D0j) at the level of a given sensor (A0j) enclosed in the intermediate unit volume can be a function of at least the following: D0j = g(DA0j, DICia, DA0ja, DAija):

[0125] · The dose (DA0j) measured by the given sensor (A0j) of the additional detector (1A),

[0126] · The dose (DICia) measured by the adjacent ionization chamber (ICia) adjacent to the intermediate unit volume, and

[0127] One or more of the following:

[0128] · The dose (DA0ja) measured by at least the adjacent sensor (A0ja) of the additional detector (1A) enclosed in the same intermediate volume and adjacent to the given sensor (A0j), and

[0129] · The dose (DAija, i>0) of the adjacent sensor (Aija, i>0) of the additional detector (1A) facing the adjacent ionization chamber (ICia).

[0130] High-resolution 2D dose distribution on the plane (X,Y) and 3D dose distribution in the volume (X,Y,Z)

[0131] As Figure 1b shown (thin dashed line), the high-resolution 2D dose distribution of the radiation beam (5) on the plane (X,Y) can be obtained by determining the doses (Dij, i≥0) calculated at the levels of all sensors (Aij, i≥0), which include the sensors (Aij, i>0) facing the ionization chamber (ICi) and the sensors (A0j) facing the inter-chamber space as described above.

[0132] The high-resolution 3D dose distribution map of the volume (Y,Z) at a given position along the X-axis (as Figure 1a and Figure 5b shown) can be obtained by establishing high-resolution 2D dose distribution maps at different positions (k) along the Z-axis, which correspond to different depths in the patient. This can be achieved using a dosimetry characterization unit that includes any of the following: as Figure 2c shown, a plurality of detectors (1.k) aligned at corresponding positions (k = 1 to K, K>1) along the Z-axis, or as Figure 2d shown, a single detector (1) configured to move to different positions (k = 1 to K, K>1) along the Z-axis. In both cases, the dose distribution measured along the Z-axis is discrete, corresponding to the discrete positions (k) of the single or multiple detectors (1, 1.k) during the measurement. As Figure 2cThe advantage of aligning multiple detectors (1.k) as shown is that characterization can be performed by a single measurement operation. The disadvantage is that, on the one hand, multiple (K) detectors (1.k, k = 1 to K) are required, and on the other hand, a part of the energy of the radiation beam (5) is released when interacting with each of the successive detectors (1.k), which may affect the values at greater depths along the Z-axis, depending on the number (K) of detectors used. The advantage of using a single detector (1) that moves to different positions (k) along the Z-axis is that only a single detector (1) is required. The disadvantage is that the measurement must be repeated several times (K), which takes longer because the detector (1) must be moved along the Z-axis to its new position and (2) must be reset before starting the next measurement operation.

[0133] Thus, the dosimetric characterization unit includes a detector (1) as described above, which is positioned at a location (k); and

[0134] · Further, the dosimetric characterization unit includes (K - 1) neighboring detectors (1.k) identical to the detector (1), which are aligned with the detector (1) along the Z-axis and are located at respective locations (k + m; m ≠ 0), as Figure 2c shown, or

[0135] · The detector (1) is configured to move to different positions (k), as Figure 2d shown. Figure 2d A detector (1) mounted on a track is shown, but the track is not necessary. It is sufficient for the detector (1) to be fixed at different positions (k).

[0136] To determine the calculated dose distribution on the plane (Y,Z) as Figure 1a and Figure 5b shown, or the dose distribution along the Z-axis as Figure 1c shown (which is just the intersection of the surface in Figure 1a with the plane y = 0 represented by the dashed line in Figure 1a ), the calculated dose distribution along the Y-axis for each position (k) can be determined independently of each other for each position (k), and the values are plotted along the Z-axis. This is shown in Figure 2e which shows the calculated dose distribution on the plane (X,Y) at different positions ((k - 1), k, (k + 1)) along the Z-axis. Figure 2f Shown in Figure 2eThe alignment along the Z-axis at the respective positions (k) of these calculated dose distributions above the plane (X, Y) (only half of the dose distribution (y ≥ 0) is shown for clarity). By repeating this operation over the entire extent of the radiation beam (5), a high-resolution calculated dose distribution map on the plane (X, Y) distributed along the Z-axis and separated by a distance (tk) can be created, as Figure 1a and Figure 5b shown.

[0137] In a preferred embodiment, instead of calculating the dose distribution above the plane (X, Y) for each position (k) independently of other positions ((k - 1), (k + 1), etc.), the dose distribution in the plane (X, Y) calculated at position (k) also takes into account the dose values measured by neighboring detectors (1k) at neighboring 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 a function of at least the following:

[0138] · The dose (DAija) measured by the corresponding sensor (Aija) at positions ((k - 1); (k + 1)) directly neighboring position (k), and / or

[0139] · The dose (DA0ja) measured by the corresponding sensor (A0ja) at positions ((k - 1); (k + 1)) directly neighboring position (k).

[0140] This allows for obtaining a smoother dose distribution along the Z-axis, with no or fewer steps between the calculated dose values (Dij, i ≥ 0) determined at different positions (k).

[0141] Method for characterizing the dosimetry of a radiation beam (5)

[0142] The present invention also relates to a method for characterizing the dosimetry of a radiation beam (5) propagating along the Z-axis, the method comprising:

[0143] · Positioning the dose detector (1) perpendicular to the Z-axis as described above,

[0144] · Propagating the radiation beam (5) along the Z-axis through the dose detector (1),

[0145] · Measuring the dose (DICi) using the ionization detector (1IC) and measuring the dose (DAij, i ≥ 0) using the additional detector (1A) of the dose detector (1),

[0146] · Calculating the calculated dose (Dij, i ≥ 0) based on the doses (DICi, DAij, DA0j) measured as such.

[0147] The detector (1) is preferably positioned in the phantom to form a dosimetry characterization unit (as Figure 2a shown), thereby controlling the WET accumulation 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 dosimetry characterization unit (as Figure 2c shown), or can be accompanied by adjacent dosimetry detectors (1.k) distributed along the Z-axis to form a 3D dosimetry characterization unit (as Figure 2b shown).

[0148] The detector (1), dosimetry characterization unit, and method of the present invention allow for the creation of a reliable high-resolution dosimetry map, which is necessary for ensuring accurate QA of current radiotherapy and new evolutions of radiotherapy, including FLASH therapy and adaptive therapy. In the framework of PSQA, the detector of the present invention allows for the very rapid determination of the dose distribution, thereby significantly reducing the PSQA operation time. It also has the advantage of improving PSQA for small fields. This is achieved by combining the high accuracy, precision, and reliability of the dosimetry values measured using the IC detector (1IC) with the high resolution obtained using 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, their disadvantages are not added, and the disadvantages of one detector are compensated by the advantages of the other detector. In this way, a synergistic effect is obtained, where the low spatial resolution of the IC detector (1IC) is compensated by the high spatial resolution of the additional detector (1A), and the high energy dependence of the additional detector (1A) is compensated by the high accuracy and precision of the values measured using the IC detector (1IC). The intelligent device (10) is essential for combining the values measured by each detector (1IC, 1A) to produce a realistic calculated dose distribution (Dij, i≥0).

[0149]

[0150]

Claims

1. A detector (1) for characterizing dose measurement of radiation, the detector comprising an ionization detector (1IC), the ionization detector being configured to characterize dose measurement of a radiation beam (5) propagating along a Z axis, the ionization detector (1IC) comprising a matrix of ionization chambers (ICi) distributed on a plane (X, Y) perpendicular to the Z axis, each ionization chamber (ICi) comprising a first electrode and a second electrode separated by a medium, wherein: The ionization detector has a first spatial resolution above the plane (X, Y), Characterized in that an additional detector (1A) which is different from the ionization detector (1IC) and has a second spatial resolution on the plane (X, Y) finer than the first spatial resolution of the ionization detector on the plane (X, Y) is positioned in series with respect to the ionization detector (1IC) along the Z axis, and Characterized in that the detector comprises or is coupled to an intelligent device (10), which is configured to calculate the distribution of the calculated dose (Dij) based on the dose (DICi) measured by the ionization detector (1IC) and the dose (DAij, DA0j) measured by the additional detector (1A).

2. The detector according to claim 1, wherein The additional detector (1A) is selected from the group consisting of: a semiconductor detector, a scintillation detector, a thermoluminescence detector, a chemical detector, wherein the chemical detector includes a thin film, a polymer gel and an alanine detector.

3. The detector according to claim 1 or 2, wherein: The ionization detector (1IC) has a physical thickness (tIC) measured along the Z axis, and the additional detector (1A) has a physical thickness (tA) measured along the Z axis, and wherein the detector among the ionization detector and the additional detector having the physical thickness (tIC, tA) that produces the lowest water equivalent thickness (WET) for a given radiation is positioned upstream along the Z axis relative to the radiation beam (5).

4. The detector according to claim 2 or 3, wherein: the additional detector (1A) is a semiconductor detector positioned upstream of the ionization detector (1IC) along the Z axis relative to the radiation beam (5), or The additional detector (1A) is a scintillation detector positioned downstream of the ionization detector (1IC) along the Z axis relative to the radiation beam (5).

5. A detector according to any one of the preceding claims, wherein: The radiation beam (5) is a beam of charged particles, preferably a proton beam, an electron beam, a helium ion beam, a carbon ion beam or an oxygen ion beam, or a beam of electromagnetic radiation, preferably a photon beam, preferably an X-ray or gamma-ray beam.

6. A detector according to any one of the preceding claims, wherein: The detector (1) has a physical thickness (t1) of less than 100 cm measured along the Z axis.

7. A detector according to any one of the preceding claims, wherein: The distance (tIC-A) between the effective measuring point of the ionization detector (1IC) and the effective measuring point of the additional detector (1A) is not greater than 5 cm, preferably not greater than 5 g / cm 2 Corresponding to WET.

8. The detector (1) according to any one of the preceding claims, wherein: The ionization chambers (ICi) are distributed on the plane (X, Y) of the ionization detector (1IC), and the resolution of the ionization detector is per cm 2 At least one ionization chamber (IC), preferably per cm 2 at least 1.5 ionization chambers (ICi), and wherein, The pixel resolution of the additional detector (1A) is at least twice the resolution of the ionization detector (1IC).

9. The detector (1) according to any one of the preceding claims, wherein: The intelligent device (10) is configured to determine the distribution of the linear energy transfer (LET) of the radiation also based on the measured doses (DICi, DAij, DA0j).

10. A detector according to any one of the preceding claims, wherein: Each ionization chamber (ICi) is separated from the adjacent ionization chambers of the same ionization detector (1IC) by an interchamber space (t0x, t0y), one or more sensors (Aij) of the additional detector facing the ionization chamber (ICi) of the ionization detector (1IC), one or more than one sensor (A0j) of said additional detector faces the interventricular space, the sensor (Aij, A0j) of the additional detector has a higher energy dependence than the ionization chamber (ICi) of the ionization detector (1IC), The calculated dose (Dij) in the unit volume enclosed at the level of the ionization chamber (ICi) or intersected by the detector (1) 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, and preferably the function Dij=f(DAij,DICi) also depends on one or more of the following: o the dose (DICia) measured by an adjacent ionization chamber (ICia) adjacent to the unit volume, o the dose (DAija) measured by the adjacent sensors (Aija) of the additional detector (1A) facing the ionization chamber (ICi) and preferably those sensors adjacent to the given sensor (Aij), and o The dose (DA0ja) measured by the adjacent sensor (A0ja) of the additional detector (1A) facing the interchamber space adjacent to the unit volume.

11. The detector according to claim 10, wherein: The calculated dose (Dij) depends on a sub-function f1(DICAij), which relates the dose (DICi) measured by the ionization chamber (ICi) to 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))), wherein the sub-function f1(DICAij) is preferably 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).

12. The detector according to claim 10 or 11, wherein: at least one sensor (A0j) of the additional detector (1A) faces the inter-chamber space, The dose (D0j) calculated for a given sensor (A0j) enclosed in an intermediate unit volume intersecting the detector (1) at the interchamber space between adjacent ionization chambers (ICia) is a function of at least D0j=g(DA0j,DICia,DAija), o said dose (DA0j) measured by a given sensor (A0j) of said additional detector (1A), and one or more of the following: o the dose (DICia) measured by the adjacent ionization chamber (ICia) adjacent to the intermediate unit volume, and one or more of the following: o the dose (DA0ja) measured by at least one adjacent sensor (A0ja) of said additional detector (1A) which is enclosed in the same intermediate volume and adjacent to said given sensor (A0j), and o The dose (DAija, i>0) of the adjacent sensor (Aija) of the additional detector (1A) facing the adjacent ionization chamber (ICia).

13. A dosimetry characterization unit configured to characterize the dosimetry on a plane (X, Y) of a radiation beam propagating on a Z axis perpendicular to the plane (X, Y) at different positions (k=1 to K, where K>1) separated from each other by a certain distance (tk) along the Z axis, wherein: The dosimetry characterization unit comprises a detector (1) according to any one of the preceding claims positioned at a position (k), and Further, the dose measurement characterization unit comprises (K-1) proximity detectors (1.k) according to any one of the preceding claims, which are aligned with the detector (1) along the Z axis and are located at corresponding positions (k+m; m≠0), or The detector (1) is configured to move to the different position (k).

14. Dosimetry characterization unit according to the preceding claim, wherein The detector (1) and preferably the proximity detector (1.k) is according to any one of claims 10 to 12, and wherein the function Dij=f(DAij,DICi) and / or D0j=g(DA0j,DICia,DAija) determined at the position (k) is also a function of one or more of: the dose (DAija) measured by the corresponding sensor (Aija) at the position ((k-1); (k+1)) directly adjacent to said position (k), and / or • The dose (DA0ja) measured by the corresponding sensor (A0ja) at the position ((k-1); (k+1)) directly adjacent to said position (k).

15. A method for characterizing dosimetry of a radiation beam (5) propagating along a Z-axis, the method comprising: Positioning the dose detector (1) according to any one of claims 1 to 12 perpendicularly to the Z axis, propagating a radiation beam (5) along the Z axis through the dose detector (1), Measuring the dose (DICi, DAij, DA0j) using the ionization detector (1IC) and the additional detector (1A) of the dose detector (1), · Calculate the calculated dose (Dij, D0j) from the dose (DICi, DAij, DAOj) thus measured.

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