pixelated scintillator

Abstract

The present invention relates to a method for fabricating a pixelated scintillator. According to the method, a first laser irradiation is applied to a plurality of first regions of a substrate according to a predetermined geometry of the pixelated scintillator to cause structural modification of the material in the plurality of first regions of the substrate (S110). When the substrate is subjected to etching, the etching proceeds at a faster rate in the plurality of irradiated first regions than in the non-irradiated regions. Etching (S120) is performed to form a plurality of first openings having the predetermined geometry of the pixelated scintillator. The plurality of first openings are filled with at least one scintillator material (S130) to form the pixelated scintillator. The resulting pixelated scintillator embedded in the substrate can be bonded to a corresponding photosensitive readout sensor substrate. This may enable the realization of cost-effective, parallax-free, single-layer or multi-layer radiation detectors with enhanced spatial resolution and sensitivity.

Description

[Technical Field]

[0001] The present invention relates to pixelated scintillators, and in particular to a method for manufacturing a pixelated scintillator, a pixelated scintillator obtained by the method, a radiation detector, a manufacturing system, and a computer program. [Background technology]

[0002] U.S. Patent Application Publication No. 2019 / 317226A1 describes an X-ray detection device. The X-ray detection device includes a substrate, a first material layer, a circuit element, a photoelectric detection element, and a columnar structure. The first material layer is disposed on the substrate. The circuit element is disposed on a bottom of the first material layer. The photoelectric detection element is disposed on the circuit element. The columnar structure is disposed correspondingly on and in contact with the photoelectric detection element.

[0003] U.S. Patent No. 5,981,959A describes a pixelated scintillation layer in which high aspect ratio pillars of scintillation material are formed. The pillars can be sized and spaced to correspond to the size and spacing of the underlying sensor array, or can be sized so that there are multiple pillars for each pixel. A method for forming a pixelated scintillation layer includes forming openings, such as wells, vias, or channels, in a body, for example, by etching thick photoresist, ion beam etching, anodic etching, etc., and filling the openings with scintillation material.

[0004] CN108363090A discloses a detector based on a bendable photodiode.

[0005] Huang Ji ET AL: "Fabrication of highly homogeneous and controllable nanogratings on silicon via chemical etching-assisted femtosecond laser modification", Nanophotonics, vol. 8, no. 5, 1 May 2019 (2019-05-01), pages 869-878, describes a chemical etching-assisted femtosecond laser fabrication process. Summary of the Invention [Problem to be solved by the invention]

[0006] Today's radiation detectors used in medical imaging primarily comprise a non-pixelated, micro-pillared scintillator layer bonded to a readout sensor substrate based on a large array of small, electronically addressable, light-sensitive pixels. An inherent problem with these so-called indirect conversion radiation detectors can be a loss of lateral resolution due to blurring of scintillation light in the scintillator layer. In addition, the spatial resolution of such detectors can decrease from the center toward the edge of the detector due to increased parallax error. These effects can become more pronounced as the pixel size of the x-ray detector decreases and / or as the x-ray detector includes multiple scintillator layers.

[0007] The above problems can be solved, at least in part, by replacing non-pixelated scintillators with pixelated scintillators, i.e., arrays of scintillator elements, also called voxels, embedded in or deposited on a substrate. Various methods have been proposed for realizing radiation detectors based on pixelated scintillators. However, most methods offer only limited improvements in detector performance and / or suffer from high manufacturing complexity.

[0008] There may be a need to provide improved methods for manufacturing pixelated scintillators for radiation detectors, such as X-ray or gamma ray detectors. [Means for solving the problem]

[0009] The invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims. The aspects of the invention described below also apply to a method for manufacturing a pixelated scintillator, to the pixelated scintillator obtained by this method, and to a radiation detector.

[0010] According to a first aspect of the present invention, there is provided a method of manufacturing a pixelated scintillator, comprising the steps of: irradiating a plurality of first regions of a substrate with a first laser irradiation according to a predetermined geometry of the pixelated scintillator, causing structural modification of a material in the plurality of first regions of the substrate such that when the substrate is subjected to etching, the etching (preferably wet chemical etching) proceeds at a higher rate in the irradiated plurality of first regions than in non-irradiated regions; performing the etching to form a plurality of first openings in the substrate, the first openings having the predetermined geometry of the pixelated scintillator; and filling the plurality of first openings with at least one scintillator material to form the pixelated scintillator.

[0011] The present disclosure proposes a new method for fabricating pixelated scintillators, e.g., focused pixelated scintillators. Laser micromachining, such as femtolaser micromachining, followed by etching, is used to form a plurality of first openings having predetermined geometries in a substrate, e.g., a glass or plastic substrate. The substrate is preferably transparent or at least partially transparent to laser irradiation. Etching is preferably performed by subjecting the substrate to wet chemical etching, such as with a KOH- or HF-based solution. However, other forms of etching, such as plasma etching or etching with gases, e.g., fluorine-containing gases, are also contemplated.

[0012] The apertures can be arranged in an array. The great flexibility of laser beam writing allows for the fabrication of apertures of customized geometries, such as high-aspect ratio apertures, apertures whose height, wall thickness, aspect ratio, geometry, pitch, and angle of inclination vary across the substrate. Additional masking steps, such as photoresist or metal masks, are not required. This method advantageously reduces process complexity and cost. The first apertures and / or the walls between the apertures can have a high aspect ratio, such as a depth-to-width aspect ratio of at least 10, more preferably at least 50, and even more preferably at least 100. These apertures are then filled with one or more scintillator materials, for example, by screen printing or binder jetting. The filled apertures can be referred to as scintillator elements or voxels of the pixelated scintillator. Thus, the apertures are filled to define the scintillator elements or voxels of the pixelated scintillator. Thus, the scintillator elements and / or the walls between the scintillator elements can also have a high aspect ratio, e.g., a depth-to-width aspect ratio of at least 10, more preferably at least 50, and even more preferably at least 100. Thus, the customized geometry of the apertures facilitates the provision of scintillator elements that also have highly customized geometries. A subsequent aperture-filling process can provide pixelated scintillators from a selection of scintillator materials and different forms of scintillator materials. For example, powder-based scintillator materials can be used. The aperture-filling process also allows for pixelated scintillators to be produced using inexpensive manufacturing methods and pixelated scintillators that are embedded in large-area solid substrates and are therefore protected.

[0013] The resulting pixelated scintillator can be bonded to a corresponding light-sensitive readout sensor substrate to provide a single-layer or multi-layer radiation detector with improved spatial resolution and sensitivity.

[0014] The proposed fabrication method for pixelated scintillators can address increasing demands for quality, versatility, precision, pixel aspect ratio, areal uniformity, robustness, and / or cost reduction, thereby facilitating new medical imaging methods such as spectral X-ray imaging and phase contrast imaging. The proposed method can be used to provide optimal size and geometry for each of the individual scintillator elements within the detector.

[0015] This is explained in more detail below, particularly with respect to the embodiment shown in FIGS.

[0016] According to one embodiment of the present invention, prior to the step of filling the plurality of first openings with at least one scintillator material to form a pixelated scintillator, the method further comprises the step of coating at least a portion of an inner surface of the at least one first opening with an optically reflective or non-transparent material.

[0017] In some examples, the sidewalls of the first aperture are coated with an optically reflective or non-transparent material. In this way, the optical signal is confined within each scintillator element. This reduces the ability of the optical signal to escape to adjacent light-sensitive pixels on the readout sensor.

[0018] In some examples, the bottom surface of the first opening is coated with an optically reflective material. Including a coating layer having an optically reflective material on the bottom of the scintillator elements in the glass substrate can increase the scintillation light output of the pixelated scintillator.

[0019] In some examples, both the sidewalls and the bottom surface of the first opening are coated with an optically reflective or non-transparent material, as will be described in more detail below, particularly with respect to the examples shown in Figures 3 and 4.

[0020] According to one embodiment of the present invention, after filling the plurality of first apertures with at least one scintillator material to form a pixelated scintillator, the method further comprises coating the at least one filled first aperture with an optically reflective or non-transparent material.

[0021] In other words, one or more filled apertures, also known as scintillator elements or voxels, can be coated with an optically reflective or non-transparent material, which can be used to fabricate pixelated scintillators with a so-called "front-illuminated" geometry.

[0022] This is explained below, particularly with reference to the example shown in FIG.

[0023] According to one embodiment of the present invention, the method comprises the steps of irradiating one or more second regions of the substrate with a second laser irradiation, performing etching (preferably wet chemical etching) to form one or more second openings, and filling the one or more second openings with an optically reflective or non-transparent material, wherein the one or more second regions are different from the plurality of first regions, and at least one second region is located between two adjacent first regions.

[0024] These additional steps allow for the fabrication of pixelated scintillators with reflective or non-transparent walls. First, high-aspect ratio trenches, such as high-aspect ratio angular trenches, are created in a substrate (e.g., a glass substrate) using laser exposure (e.g., femtolaser exposure) followed by etching. A thin solid layer of glass remains as the supporting base substrate for the trench system. Second, the trenches can be filled with an optically reflective material. For example, a reflective TiO pigment layer can be applied by capillary filling from a TiO-based paint. Alternatively, the trenches formed by the etching step can be filled with non-transparent trench walls.

[0025] This is explained below, particularly with reference to the example shown in FIGS.

[0026] According to one embodiment of the present invention, the method further comprises bending the substrate in one or two dimensions to shape the substrate according to a desired curvature.

[0027] In this embodiment, a bendable substrate (eg, thin glass or plastic foil) for the scintillator can be used to allow for the fabrication of curved radiation detectors.

[0028] According to one embodiment of the present invention, at least one of the first laser radiation and the second laser radiation is generated by a focused pulsed femtosecond laser.

[0029] Femto laser micromachining technology has demonstrated the feasibility of fabricating various monolithically integrated devices, including optofluidic, optomechanical, and photonic devices. Transparent substrate materials, typically glass (e.g., fused silica, for example), polymers, dielectrics, and crystals, allow the laser beam to be focused and energy to be deposited almost anywhere within the substrate material. The energy deposition results in structural modification of the material, and subsequent wet chemical etching proceeds at a much higher rate in exposed areas than in unexposed areas. This enhancement of local sensitivity to wet chemical etching (etch selectivity) depends on various parameters of the femto laser, such as pulse width, pulse energy, and pulse repetition frequency.

[0030] According to one embodiment of the present invention, the plurality of first apertures are angled towards a common focal point.

[0031] As a result, pixelated scintillators can have the sidewalls of the scintillator elements better aligned toward the focal spot of the x-rays or gamma rays, thereby reducing parallax and pixel edge effects. Therefore, such angled (focusing) scintillators can provide higher modulation transfer functions and detection quantum efficiencies during imaging. Examples of angled pixelated scintillators are shown in Figures 2, 4, and 6.

[0032] According to one embodiment of the present invention, the at least one scintillator material filled in the plurality of first openings has a relatively greater thickness at the center of the substrate than at the edge of the substrate.

[0033] In this way, a uniform scintillator absorption depth can be achieved across the detector, as will be further described below, particularly with respect to the example shown in Figures 9(a)-9(c).

[0034] According to one embodiment of the present invention, at least two scintillator materials having different scintillator emission spectra are filled into the plurality of first openings.

[0035] The sensitivity of x-ray detectors using pixelated scintillators can be limited by an inadequate match between the spectral characteristics of the scintillator and the photodiode. The use of multiple scintillator materials allows the emission spectrum of the scintillator material in a scintillator element to be matched to the photodiode sensitivity spectrum.

[0036] This is explained in more detail below, particularly with respect to the embodiment shown in Figures 10(a) and 10(b).

[0037] According to one embodiment of the present invention, at least two scintillator materials are deposited successively in at least one of the first openings. Alternatively or additionally, at least one scintillator element of the pixelated scintillator comprises a plurality of sub-scintillator elements, and at least two sub-scintillator elements of the at least one scintillator element are filled with different scintillator materials.

[0038] This is explained in more detail below, particularly with respect to the embodiment shown in Figures 10(a) and 10(b).

[0039] According to one embodiment of the present invention, the substrate comprises a glass material or a plastic material.

[0040] According to a second aspect of the present invention, there is provided a pixelated scintillator obtainable by the method according to the first aspect and any related examples. The pixelated scintillator has a plurality of first openings in a substrate, and the plurality of first openings in the substrate are filled with at least one scintillator material. The pixelated scintillator may be a high-aspect ratio pixelated scintillator. Preferably, the plurality of first openings and / or walls between the first openings of the pixelated scintillator have a depth-to-width aspect ratio of at least 10, more preferably at least 50, and even more preferably at least 100. The substrate is transparent or at least partially transparent to laser irradiation. For example, glass (such as fused silica as a non-limiting example), polymer, dielectric, or crystal can be used as a transparent substrate material. The pixelated scintillator is a focusing scintillator, and the plurality of first openings are angled toward a common focal point. The focusing pixelated scintillator can thereby provide improved modulation transfer function and detection quantum efficiency during imaging.

[0041] Thus, pixelated scintillators can be fabricated with high accuracy (precision) of the sizing and / or individual geometry of the individual scintillator voxels. In the fabrication methods described in relation to the first aspect of the invention, scintillators can be fabricated with focusing scintillator voxels in a transparent substrate. High dimensional and geometric stability may enable robust optical coupling of the scintillator substrate to the sensor substrate, stacking of multiple scintillator substrates in a multi-layer detector, etc. The walls may be smooth to reduce light scattering at the boundaries.

[0042] Glass can be a preferred transparent substrate for pixelated scintillators because the material is solid, hard, flat, chemically inert, and available as a large-area substrate. The glass substrate can ensure a high-quality, robust optical bond between the scintillator substrate and the photosensitive sensor substrate, which is also glass in the majority of current medical X-ray detectors. In this way, the scintillator and sensor substrates can have the same properties, such as the thermal expansion coefficient.

[0043] According to a third aspect of the present invention there is provided a radiation detector comprising a pixelated scintillator according to the second aspect and a pixelated photosensitive readout sensor.

[0044] Optical crosstalk occurs when light-sensitive pixels on a sensor receive optical signals from multiple scintillator elements. The radiation detectors described herein can reduce this effect by improving the lateral alignment between the light-sensitive pixels and the scintillator elements and minimizing the distance (gap) between the scintillator and the sensor.

[0045] Additionally, the sensitivity of X-ray detectors that use pixelated scintillators can be limited by a low fill factor. The fill factor of the radiation detection described herein can be improved by providing precise alignment of the scintillator elements with the photosensitive areas of the pixels on the sensor.

[0046] This is explained in more detail below, particularly with respect to the example shown in FIG.

[0047] According to one embodiment of the present invention, the radiation detector is a multi-layer detector that includes a plurality of stacked pixelated scintillators.

[0048] The resulting pixelated focusing scintillator can be advantageous for multi-layer detectors because it reduces signal cross-contamination between different detector layers. Multi-layer detectors including stacked pixelated scintillators can be advantageously used for spectral imaging. This is described below, particularly with respect to the example shown in Figures 11(a)-11(c).

[0049] According to one embodiment of the present invention, the pixelated scintillator and the pixelated photosensitive readout sensor are constructed and arranged to form a radiation detector in either a so-called "back-illuminated" geometry or a so-called "front-illuminated" geometry.

[0050] Pixelated scintillators can be incorporated into X-ray detectors in either of these geometries. In the front-illuminated geometry, X-rays or gamma rays first strike the scintillator and are absorbed there. The resulting scintillation light is detected by a photosensitive readout sensor. This is the most common geometry in X-ray detectors today. In the back-illuminated geometry, X-rays or gamma rays first strike the photosensitive readout sensor substrate. The X-rays or gamma rays pass through the photosensitive readout sensor substrate and are then absorbed by the scintillator. The resulting scintillation light is detected by the photosensitive readout sensor.

[0051] An example of a radiation detector with back-illuminated geometry is shown in Figure 7. An example of a radiation detector with front-illuminated geometry is shown in Figure 8.

[0052] The pixelated scintillator can be fabricated using a fabrication system including an optical laser system, an etching system, and a material deposition system, and a control system including one or more controllers. The control system can be configured to control the optical laser system to irradiate a plurality of first regions of a substrate with a first laser irradiation according to a predetermined geometry of the pixelated scintillator, causing structural modification of the material in the plurality of first regions of the substrate, such that when the substrate is subjected to etching, the etching proceeds at a higher rate in the plurality of irradiated first regions than in non-irradiated regions. The control system can be configured to control a chemical etching system to perform the etching, thereby forming a plurality of first openings in the substrate, the first openings having the predetermined geometry of the pixelated scintillator. The control system can be configured to control the material deposition system to fill the plurality of first openings with at least one scintillator material to form scintillator elements of the pixelated scintillator. This will be described in more detail below, particularly with respect to the example shown in FIG. 12 .

[0053] A computer program may be provided that includes instructions for causing a manufacturing system to perform the steps of the method according to the first aspect and any associated examples.

[0054] A computer readable medium may be provided having a computer program stored thereon.

[0055] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments illustrated by way of example in the following description and with reference to the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0056] [Figure 1] 1 is a flow chart illustrating an example method for fabricating a pixelated scintillator. [Figure 2] FIG. 2 is a diagram showing an example of a manufacturing process related to FIG. 1. [Figure 3] 10 is a flowchart illustrating another example method for manufacturing a pixelated scintillator. [Figure 4] FIG. 4 is a diagram showing another example of a manufacturing process related to FIG. 3. [Figure 5] 10 is a flowchart illustrating a further example of a method for manufacturing a pixelated scintillator. [Figure 6] FIG. 6 is a diagram showing another example of a manufacturing process related to FIG. 5. [Figure 7] FIG. 1 shows a schematic diagram of an example of a radiation detector fabricated by coupling a pixelated scintillator to a readout sensor in a back-illuminated geometry. [Figure 8] FIG. 1 shows a schematic diagram of an example of a radiation detector fabricated by coupling a pixelated scintillator to a readout sensor in a front-illuminated geometry. [Figure 9] 9(a)-9(c) are schematic diagrams illustrating how the spatial resolution of a radiation detector in a back-illuminated geometry can be improved by optimizing the design of the scintillator coupled to the readout sensor. [Figure 10] 10(a) and 10(b) illustrate examples where scintillator elements composed of multiple scintillator materials can be used to improve detective quantum efficiency (DQE) for certain clinical applications. [Figure 11] 11(a)-11(c) illustrate the advantages of pixelated focusing scintillators in multi-layer detectors to minimize signal cross-contamination between different detector layers. [Figure 12] FIG. 1 illustrates an example system for manufacturing a pixelated scintillator. DETAILED DESCRIPTION OF THE INVENTION

[0057] It should be noted that the drawings are merely schematic and are not drawn to scale. In the drawings, elements corresponding to elements already described may have the same reference numerals. Examples, embodiments, or optional features should not be understood as limiting the invention as defined in the claims.

[0058] Detailed Description of the Embodiments

[0059] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey the scope of the invention to those skilled in the art. Those skilled in the art will understand that the following descriptions of embodiments of the invention are illustrative and not intended to be in any way limiting. Other embodiments of the present invention will be readily apparent to those skilled in the art having the benefit of this disclosure. Like reference characters refer to like elements throughout.

[0060] Although the following detailed description contains many details for purposes of explanation, those skilled in the art will appreciate that many variations and modifications to the following details are within the scope of the present invention. Accordingly, the following embodiments of the present invention are described without any loss of generality to the claimed invention and without imposing limitations on the claimed invention. In the following embodiments, etching of the substrate after irradiation with laser radiation is exemplified using wet chemical etching. Such etching is preferably carried out using, for example, a KOH or HF-based solution. However, other forms of (chemical) etching, such as plasma etching, etching with gases such as fluorine-containing gases, etc., can also be used instead of wet chemical etching.

[0061] Various methods for fabricating pixelated scintillators have been proposed in the past, but most suffer from one or more drawbacks, including high cost. For example, dry reactive ion etching of silicon wafers followed by CsI(Tl) filling in a melting process may not be suitable for creating focused trenches in silicon because the etching process is highly sensitive to silicon crystal orientation. Laser ablation of a CsI(Tl) film followed by the deposition of a reflective coating within the laser-cut trenches can be used to improve optical isolation between scintillator elements. However, this method can suffer from a significant reduction in scintillator sensitivity, likely due to laser-induced microstructural modifications of the CsI(Tl) film. For example, additive manufacturing of scintillator elements by 3D printing (e.g., photopolymerization) from a scintillator particle-in-binder powder system can be used to fabricate 3D-printed scintillator structures. However, such structures may not be mechanically robust enough to withstand the subsequent assembly process to fabricate the X-ray detector. The choice of scintillator can also be limited by the ability to create a printable paste.

[0062] To address one or more of the above-mentioned problems, the present disclosure proposes a method and fabrication of a pixelated scintillator that may allow for selection from a wide variety of low-cost scintillator materials (e.g., powder-based scintillator materials) to achieve a pixelated scintillator that is embedded and protected in a solid, large-area substrate.

[0063] 1 shows a flow chart illustrating a method 100 for manufacturing a pixelated scintillator, i.e., an array of scintillator elements. This method will be described in relation to FIG.

[0064] In step S110, a first laser irradiation 12a is applied to a plurality of first regions of the substrate 14 according to a predetermined geometry of the pixelated scintillator, causing structural modification of the material within the plurality of first regions of the substrate, such that wet chemical etching proceeds at a faster rate in the plurality of irradiated first regions than in the non-irradiated regions.

[0065] The substrate can be made of a material that is transparent or at least partially transparent to the first laser irradiation. For example, glass (such as, but not limited to, fused silica), polymers, dielectrics, or crystals can be used as transparent substrate materials because the laser beam can be focused almost anywhere within the material and energy can be deposited almost anywhere in the volume.

[0066] Due to the nonlinear nature of ultrafast laser-matter interactions, relatively low laser energy is locally absorbed wherever the laser spot is focused. This nonlinear absorption of laser energy allows for the use of moderate average laser powers, while very large instantaneous powers are locally achieved during laser exposure. It is also possible to fabricate features smaller than the wavelength of the laser itself (e.g., 1030 nm). As an example, the first laser irradiation can be generated by a focused, pulsed femtosecond laser. The "femtoprinting" process, which uses femtolaser micromachining, a subtractive 3D printing technique, can create narrow, deep channels in glass with high trench aspect ratios (TAR > 100), comparable to or even higher than those achieved with competing processes such as reactive ion etching (RIE).

[0067] The energy deposition results in structural modification of the material, so that subsequent wet chemical etching proceeds at a much higher rate in exposed areas than in unexposed areas. This local enhanced susceptibility to wet chemical etching (etch selectivity) depends on various laser parameters such as pulse duration, pulse energy, and repetition rate.

[0068] Examples of predetermined geometries of pixelated scintillators include, among others, one-dimensional (1D) designs, two-dimensional (2D) designs (e.g., rectangular or hexagonal scintillator elements), and customized scintillator element designs (e.g., 1 1 / 2D) having flexible scintillator element pitch, scintillator element ratio, and / or scintillator element geometry. The predetermined geometry of the pixelated scintillator can include information such as height across the substrate, wall thickness, aspect ratio, scintillator element geometry, scintillator element pitch, angular tilt, etc.

[0069] In step S120, wet chemical etching is performed to form a plurality of first openings with predetermined geometries in the pixelated scintillator. Because wet chemical etching proceeds at a much faster rate in exposed areas than in unexposed areas, precise structures with predetermined geometries can be formed. The proposed method offers the possibility to optimize the size and geometry of individual scintillator elements within the detector. Laser exposure can be flexibly programmed across the entire substrate. Thus, the openings can have customized geometries, such as high aspect ratio openings and / or openings with walls, heights, wall thicknesses, aspect ratios, geometries, pitches, tilt angles, etc., that vary across the substrate.

[0070] This method can enable the realization of multi-layer detectors for spectral imaging, where corresponding scintillator elements of the upper and lower scintillator layers can be precisely optimized and positioned relative to each other.

[0071] The laser exposure can be controlled so that the first opening does not extend completely to the other side of the substrate 14, as shown in Figure 2. A thin layer of the substrate remains as a supporting base substrate for the scintillator elements of the pixelated scintillator.

[0072] 2, an optical laser system generating the first laser illumination can be designed and programmed to write a particular structure (e.g., an array) of first openings 16 characterized by a slight continuous increase in trench angle from the center toward the periphery of the substrate 14. The optical laser system can also take into account the difference in refractive index at the air-substrate interface and the increased optical path length for the first openings 16 toward the periphery of the substrate 14.

[0073] In step S130, the plurality of first openings 16 are filled with at least one scintillator material 18 to form a pixelated scintillator 20.

[0074] The plurality of first openings 16 may be filled with one or more selected scintillator materials using any suitable application method. Depending on the detector design and its imaging application, various scintillator materials, such as GOS, CsI, perovskite nanoparticles, quantum dot materials, etc., can be selected with various additives, such as dopants and binders, and in different formats, including, but not limited to, powders, pastes, and suspensions. There are also many options for possible scintillator deposition methods, including, but not limited to, 3D printing, binder jetting, screen printing, slot-die coating, flex printing, spin coating, and powder melting.

[0075] The methods described herein enable selection from a variety of inexpensive (e.g., powder-based) scintillator materials and fabrication methods to realize pixelated scintillators embedded and protected in large-area solid substrates. Furthermore, the methods described herein may enable improved environmental and mechanical protection by embedding small, fragile scintillator structures in solid substrates, such as glass substrates. The fill factor can be improved by precise alignment of the active photosensitive area of ​​a pixel on the sensor with the scintillator element. The methods may enable fabrication of focused scintillator elements with predetermined geometries and sharp boundaries. For example, the focused scintillator shown in FIG. 2, i.e., an angled scintillator, can reduce pixel edge effects. The methods described herein can reduce optical crosstalk in X-ray detectors by achieving lateral alignment between the photosensitive pixel and the scintillator element and minimizing the distance (gap) between the sensor and the scintillator. This is explained below, particularly with reference to the example shown in FIG. 7.

[0076] A pixelated scintillator can have a one-dimensional (1D), two-dimensional (2D), or three-dimensional (3D) array of scintillator elements. Pixelated scintillators can be used in radiographic detectors to detect ionizing radiation, such as X-rays and gamma rays, thereby imaging. Pixelated scintillators can be used in imaging systems such as positron emission tomography (PET), single photon emission tomography (SPECT), and computed tomography (CT) medical imaging systems. Pixelated scintillators can also be used in non-medical imaging systems, such as industrial radiography for the inspection of industrial parts. The material of such scintillator elements is selected to generate a pulse of scintillation light in response to each received X-ray or gamma quantum. The scintillation light is then detected by a photodetector array optically coupled to the scintillator elements.

[0077] The point spread function of current radiation detectors, primarily based on continuous (non-pixelated) scintillators, can be broadened by blurring of scintillation light in the scintillator after interaction of X-rays or gamma rays with the scintillator. This is primarily due to scintillator light scattering and reflection effects at the scintillator grain boundaries. These effects are most pronounced in polycrystalline (powdered) layers such as GOS, but also occur in columnar structured layers such as CsI. To this end, the pixelated scintillators of the present disclosure can optionally be configured to provide optical isolation of the scintillators by including an optical isolation layer between the scintillator elements so that scintillation photons generated in one scintillator element cannot easily pass from that scintillator element to another. When scintillator elements are optically isolated, the majority of generated scintillation photons are contained within the scintillator element where they were generated, e.g., by total internal reflection. The separator material can include, by way of non-limiting example, an optically reflective material, a non-transparent material, etc. In this way, the light signal is confined within each scintillator element, regardless of the scintillator material type, and escape of the light signal to adjacent light-sensitive pixels on the readout sensor is nearly impossible.

[0078] There are various approaches to fabricating pixelated scintillators with optical isolation layers.

[0079] 3 shows an exemplary flow chart illustrating a method 100 for fabricating a pixelated scintillator with an optical isolation layer. This method will be described in relation to FIG.

[0080] In step S110, a first laser irradiation 12a is applied to a plurality of first regions of the substrate 14 according to a predetermined geometry of the pixelated scintillator, causing structural modification of the material in the plurality of first regions of the substrate, such that wet chemical etching proceeds at a faster rate in the plurality of irradiated first regions than in the non-irradiated regions.

[0081] In step S120, wet chemical etching is performed to form a plurality of first openings 16 having a predetermined geometry of the pixelated scintillator.

[0082] In step S122, at least a portion of the inner surface of at least one first opening 16 is coated with a separator material 22, such as an optically reflective or non-transparent material. In some examples, as shown in FIG. 4, both the sidewalls and bottom surface of the first opening are coated with the separator material. In some examples (not shown), only the sidewalls of the first opening 16 are covered with the separator material. There is a wide selection of possible material coating methods for the separator material. For example, atomic layer deposition (ALD), a well-established technique, can be used to deposit a highly conformal multilayer coating (e.g., SiO2 / Al2O3 / Al) into the high-aspect-ratio trench. Other material coating techniques can be based on thermal evaporation, thermal melting, capillary filling from a suspension, or paste.

[0083] In step S130, the plurality of first openings 16 are filled with at least one scintillator material 18 to form a pixelated scintillator 20.

[0084] 5 shows an exemplary flow chart illustrating a method 100 for fabricating a pixelated scintillator with reflective or non-transparent trench walls. This method will be described in connection with FIG.

[0085] In step S102, a second laser irradiation 12b is applied to one or more second regions of the substrate 14. The first laser irradiation 12a and the second laser irradiation 12b may represent different sequences of laser exposure.

[0086] In step S104, wet etching is performed to form one or more second openings 24. Similarly, the laser exposure can be controlled so that the second openings 24 do not extend completely to the other side of the substrate 14. A thin solid layer of the substrate remains as a supporting base substrate for the system of second openings 24.

[0087] In step S106, one or more second openings 24 are filled with a separator material 22, such as an optically reflective or non-transparent material. For example, a reflective TiO pigment can be applied by capillary filling from a TiO-based paint. The one or more second regions are different from the plurality of first regions, and at least one second region is disposed between two adjacent first regions.

[0088] In step S110, a first laser irradiation 12a is applied to a plurality of first regions of the substrate 14 according to a predetermined geometry of the pixelated scintillator, causing structural modification of the material in the plurality of first regions of the substrate, such that wet chemical etching proceeds at a faster rate in the plurality of irradiated first regions than in the non-irradiated regions.

[0089] In step S120, wet chemical etching is performed to form a plurality of first openings 16 having a predetermined geometry of the pixelated scintillator.

[0090] In step S130, the plurality of first openings 16 are filled with at least one scintillator material 18 to form a pixelated scintillator 20.

[0091] 5 and 6, the reflective or non-transparent trench walls are formed before the scintillator elements. In some other examples (not shown), the separator layer may be formed after the scintillator elements. That is, steps S102-S106 may be performed after steps S110-S130.

[0092] In some examples, a protective layer can be added onto the scintillator substrate of the pixelated scintillator, such as pixelated scintillator 20 shown in Figures 2, 4, and 6, to prevent loss of scintillator material from the scintillator elements and / or to prevent loss of separator material from the trenches.

[0093] In some examples, a reflector layer, e.g., a layer of optically reflective material, can be added to the backside of a sensor substrate coupled to a pixelated scintillator, e.g., pixelated scintillator 20 shown in Figures 2, 4, and 6. This is described below, particularly with respect to the exemplary radiation detectors shown in Figures 7 and 8.

[0094] In some examples, a reflector layer, e.g., a layer of optically reflective material, can be added to the bottom of the scintillator elements in the pixelated scintillator substrate, e.g., the pixelated scintillator 20 shown in Figures 2 and 4, or to the backside of the pixelated scintillator substrate, e.g., the pixelated scintillator 20 shown in Figures 2 and 6. This can increase the scintillation light output of the pixelated scintillator.

[0095] In some examples, an x-ray imaging system can have a curved pixelated scintillator rather than a flat pixelated scintillator, in which case the microfabrication of the scintillator elements can still be performed on a flat, bendable substrate such as a thin glass or plastic foil, which can then be slightly bent in one or two dimensions, for example, using a mold at elevated temperature, to achieve the desired curvature, allowing for the fabrication of a curved radiation detector.

[0096] The point spread function of current radiation detectors, primarily based on continuous scintillators (i.e., non-pixelated scintillators), can be magnified by parallax errors caused by varying absorption depths of incident X-rays within the scintillator layer across the detector. These effects are less pronounced at the center of the detector (normal incidence of X-rays) but become stronger toward the edges (oblique incidence of X-rays). Therefore, a further option is for the pixelated scintillators of the present disclosure to be configured with different scintillator thicknesses along the substrate to achieve a uniform scintillator absorption thickness for all pixels across the substrate. For example, at least one scintillator material filled in the multiple first apertures may have a reduced thickness from the center of the substrate toward the edge of the substrate. Such a structure can be used to reduce both parallax and pixel edge effects. This is described in more detail below, particularly with reference to the examples shown in Figures 9(a)-9(c).

[0097] The sensitivity of an X-ray detector based on a pixelated scintillator can be limited by an inadequate match between the spectral characteristics of the scintillator and the photodiode. The method described herein allows for matching the emission spectrum of the scintillator material in the scintillator element with the photodiode sensitivity spectrum to improve DQE. To this end, the pixelated scintillator of the present disclosure can optionally be configured to have a composite scintillator material composed of multiple scintillator materials. In some examples, at least two scintillator materials are sequentially deposited in at least one of the first apertures. Alternatively or additionally, at least one scintillator element of the pixelated scintillator has multiple sub-scintillator elements, and at least two sub-scintillator elements of the at least one scintillator element are filled with different scintillator materials. This is described in more detail below, particularly with reference to the examples shown in FIGS. 10(a) and 10(b).

[0098] The pixelated scintillator 20 can be incorporated into radiation detectors in a variety of different geometries. For example, the pixelated scintillator 20 can be incorporated into radiation detectors having a front-illuminated geometry or a back-illuminated geometry, as described above.

[0099] FIG. 7 schematically illustrates an example of a radiation detector 40 fabricated by coupling a pixelated scintillator 20 to a pixelated photosensitive readout sensor 30 in a back-illuminated geometry. In this example, a pixelated scintillator 20 having the configuration of FIG. 4 is shown. However, it will be understood that other configurations, such as the pixelated scintillator 20 shown in FIGS. 2 and 6, can also be used in the radiation detector 40. The pixelated photosensitive readout sensor 30 includes a sensor substrate 32 and a photodetector array having a plurality of photosensitive pixels 34 in optical communication with the scintillator array 20. In some examples, the photodetector array 34 may be a silicon photomultiplier array, i.e., SiPM, an array of photodiodes, e.g., a Philips Digital Photon Counting SiPM photodetector array. Alternatively, the photodetector array 34 may include an array of avalanche photodiodes, photomultiplier tubes, position-sensitive photodetectors, or the like. In these examples, the photodiodes, photomultiplier tubes, and photodetectors form photosensitive pixels. The fill factor (i.e., X-ray sensitivity) can be improved by aligning the scintillator elements 18 with the light-sensitive pixels 34 across the sensor substrate area. Furthermore, the free space between the scintillator elements 18 exactly overlaps the dead area between the light-sensitive pixels 34. Compared to a front-illuminated geometry, a back-illuminated geometry can improve the spatial resolution and sensitivity of the radiation detector. In addition, a back-illuminated geometry can reduce the effective distance between the pixelated scintillator and the readout sensor. The effective distance can indicate the average distance of an X-ray absorption event to the readout sensor. Coupling of the scintillator to the sensor may be achieved, for example, by gluing, using an adhesive film, or mechanical clamping. The radiation detector 40 can be used, for example, in SPECT, PET, X-ray, or CT imaging systems.

[0100] Optionally, a reflector layer (not shown), e.g., a layer of optically reflective material, can be applied to the back surface of the sensor substrate to reflect some of the scintillation light emitted from a backlight located below the scintillator substrate back to the photodiode.

[0101] Figure 8 shows schematically another example of a radiation detector 40 fabricated by coupling a pixelated scintillator 20 to a readout sensor 30 in a front-illuminated geometry. In comparison to the radiation detector shown in Figure 7, the pixelated scintillator shown in Figure 8 is positioned toward the X-rays or gamma rays. Thus, the X-rays or gamma rays first pass through the pixelated scintillator 20 and then strike the readout sensor 30. The apertures defining the scintillator elements can be angled accordingly.

[0102] Optionally, a reflective layer (not shown), e.g., a layer of an optically reflective material, may be applied to the back surface of the scintillator substrate. If necessary, a non-transparent material may be applied to the first aperture wall (also called the scintillator element wall) of the scintillator substrate. Compared to an optically reflective material, the use of a non-transparent material, e.g., a light-absorbing material, may reduce sensitivity but increase spatial resolution, which is interesting for non-medical applications where dose is less critical.

[0103] Other radiation detector configurations are shown below in Figures 9-11. These figures may show pixelated scintillators having the structure shown in Figure 4, it being understood that other pixelated scintillators, such as the pixelated scintillator 20 shown in Figures 2 and 6, may also be realized in these radiation detector configurations.

[0104] Figures 9(a) and 9(c) show schematic diagrams illustrating how the spatial resolution of a radiation detector in a back-illuminated geometry can be improved by optimizing the design of the scintillator coupled to the readout sensor. As shown in Figure 9(a), for a non-pixelated scintillator, resolution decreases from the center toward the edge of the detector due to increased parallax effects, primarily caused by obliquely incident X-rays or gamma rays. Figure 9(b) shows an example of a pixelated non-focusing scintillator in which at least one scintillator material filled in multiple first apertures has the same or similar thickness. In such a radiation detector structure, pixel edge effects arising from the scintillator element sidewalls still reduce spatial resolution toward the detector edge. Figure 9(c) shows an example of a pixelated focusing scintillator. In such a radiation detector structure, both the parallax effect and the pixel edge effect can be reduced because the sidewalls of the scintillator elements are aligned toward the X-ray focal spot or gamma-ray beam. Furthermore, uniform scintillator absorption depth throughout the detector can be achieved by slightly reducing the scintillator thickness from the center toward the edge. Although Figures 9(a)-9(c) show a radiation detector with a back-illuminated geometry as an example, it will be appreciated that radiation detection in a front-illuminated geometry can also be improved by optimizing the design of the scintillator coupled to the readout sensor according to the embodiment shown in Figure 9(c).

[0105] 10(a) and 10(b) show examples where scintillator elements composed of multiple scintillator materials can be used to improve DQE for particular clinical applications. Generally, this can be achieved by maximizing the overlap between the scintillator emission spectrum and the photodiode sensitivity spectrum, and / or maximizing the X-ray or gamma-ray absorption of the scintillator.

[0106] The example of FIG. 10(a) shows three different scintillator layers composed of scintillator materials 18a, 18b, and 18c sequentially deposited within each scintillator element, which can be achieved using a binder jetting device. For example, each light-sensitive pixel is bounded by a scintillator element filled with multiple scintillator layers on top of each other. For improved light collection in back-illuminated geometries, the emission and radiation absorption of the stack can be selected so that all layers closest to the readout sensor are transparent to the emission of all layers further away from the sensor. While FIG. 10(a) shows three scintillator layers as an example, it will be understood that in some other examples, the radiation detector can have a different number of scintillator layers, such as two, four, or more scintillator layers.

[0107] The example of FIG. 10(b) shows that each scintillator element is composed of three sub-scintillator elements, each filled with a different material. For example, a photosensitive pixel can have several smaller photosensitive sub-pixels, such as sub-pixels 34a, 34b, and 34c shown in FIG. 10(b), which are coupled to corresponding scintillator sub-scintillator elements filled with different scintillator materials, such as scintillator materials 18a, 18b, and 18c shown in FIG. 10(b). The radiation absorption characteristics of the scintillator sub-scintillator elements can be selected to achieve maximum discrimination between object materials in spectral imaging. While FIG. 10(b) shows three sub-pixels as an example, it will be understood that in some other examples, each photosensitive pixel can have a different number of sub-pixels, such as two sub-pixels, four sub-pixels, or more sub-pixels.

[0108] Figures 10(a) and 10(b) may show a radiation detector with a back-illuminated geometry as an example, and it will be understood that radiation detection with a front-illuminated geometry may also be improved by having scintillator elements made up of multiple scintillator materials according to the example shown in Figures 10(a) and 10(b).

[0109] 11(a)-11(c) show that pixelated focusing scintillators are advantageous for multi-layer detectors to minimize signal cross-contamination between different detector layers. Accurate stacking and alignment of corresponding focusing scintillator elements is possible by precisely positioning them on the glass substrate using femtolaser microstructuring, which can ensure that signal cross-contamination between detector layers is reduced.

[0110] FIG. 11(a) shows a two-layer radiation detector based on two sensors, and FIG. 11(b) shows a three-layer radiation detector based on three sensors. Both radiation detectors are in a back-illuminated geometry with standard stacked sensors. FIG. 11(c) shows an alternative three-layer radiation detector based on two sensors. In this case, the bottom sensor is photosensitive on both sides (a so-called "bidirectional" sensor), i.e., the pixels are designed to capture scintillation light emitted from the top and bottom scintillator elements. While FIGS. 11(a)-11(c) show a radiation detector with a back-illuminated geometry as an example, it will be understood that radiation detection in a front-illuminated geometry can also be improved using the exemplary configurations shown in FIGS. 11(a)-11(c). In some examples, such as the example shown in FIG. 11(c), the radiation detector may be configured to have both a front-illuminated geometry and a back-illuminated geometry.

[0111] 12 illustrates an example of a system 200 for manufacturing a pixelated scintillator. The system 200 includes an optical laser system 210, a chemical etching system 220, a material deposition system 230, and a control system 240.

[0112] Control system 240 may include one or more controllers. Examples of controller components used in various embodiments of the present disclosure include, by way of non-limiting example, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0113] The control system 240 is configured to control the optical laser system 210 to irradiate the plurality of first regions of the substrate with first laser irradiation according to a predetermined geometry of the pixelated scintillator, thereby causing structural modification of the material in the plurality of first regions of the substrate, such that wet chemical etching proceeds at a higher rate in the plurality of irradiated first regions than in the non-irradiated regions. The optical laser system 210 can include a femtosecond laser.

[0114] The control system 240 is configured to control the chemical etching system 220 to perform wet chemical etching to form a plurality of first openings having predetermined geometries of the pixelated scintillator to form scintillator elements of the pixelated scintillator. The wet chemical etching can be performed using, for example, a KOH or HF-based solution. An example of wet chemical etching using KOH after irradiation with a femtosecond laser is shown in Huang Ji et al., "Fabrication of highly homogeneous and controllable nanogratings on silicon via chemical etching-assisted femtosecond laser modification."

[0115] The control system 240 is configured to control the material deposition system 230 to fill the plurality of first openings with at least one scintillator material to form a pixelated scintillator. The material deposition system 230 can include systems for deposition using techniques such as 3D printing, binder jetting, screen printing, slot-die coating, flex printing, spin coating, powder melting, and the like.

[0116] In another exemplary embodiment of the invention, a computer program or a computer program element is provided, characterized in that it is adapted to perform, on a suitable system, the method steps of the method according to one of the previous embodiments.

[0117] Thus, the computer program element can be stored in a computer unit which can be part of an embodiment of the present invention. This computing unit can be configured to perform or direct the execution of the steps of the above-mentioned method. Furthermore, the computing unit can be adapted to operate each component of the above-mentioned device. The computing unit can be configured to operate automatically and / or to execute a user's order. The computer program can be loaded into the working memory of a data processor. The data processor can thus be equipped to perform the method of the present invention.

[0118] This exemplary embodiment of the present invention encompasses both computer programs that use the present invention from the beginning, and computer programs that convert existing programs into programs that use the present invention by means of an update.

[0119] Furthermore, the computer program element may provide all the steps necessary to carry out the procedures of the exemplary embodiments of the procedures described above.

[0120] According to a further exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is presented, the computer readable medium having stored thereon a computer program element, the computer program element being as described by the preceding section.

[0121] The computer program may be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless communication systems.

[0122] However, alternatively the program may be presented over a network such as the World Wide Web and downloaded from such a network into the working memory of a data processor. According to a further exemplary embodiment of the invention, a medium for making a computer program element available for downloading is provided, the computer program element being configured to perform a method according to one of the aforementioned embodiments of the invention.

[0123] It should be noted that the embodiments of the present invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method-type claims, and other embodiments are described with reference to apparatus-type claims. However, those skilled in the art will understand from the above and below description that, unless otherwise specified, any combination of features belonging to one type of subject matter, as well as any combination between features relating to different subject matters, is disclosed in the present application. However, all features can be combined to provide a synergistic effect that is greater than the simple sum of the features.

[0124] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered exemplary or explanatory and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the dependent claims.

[0125] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. Measures recited in mutually different dependent claims may be advantageously combined. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. 1. A method of manufacturing a pixelated scintillator, comprising: irradiating a plurality of first regions of a substrate with a first laser irradiation according to a predetermined geometry of a pixelated scintillator, causing structural modification of material in the plurality of first regions of the substrate such that, when the substrate is subjected to etching, etching proceeds at a higher rate in the irradiated plurality of first regions than in non-irradiated regions; performing the etching to form a plurality of first openings in the substrate, the first openings having a predetermined geometry of the pixelated scintillator; filling the plurality of first openings with at least one scintillator material to form a pixelated scintillator; A method having the following.

2. The method further comprises: coating at least a portion of an inner surface of at least one of the first openings with an optically reflective or non-transparent material prior to filling the plurality of first openings with the at least one scintillator material to form the pixelated scintillator.

2. The method of claim 1, comprising:

3. The method further comprises: After filling the plurality of first apertures with the at least one scintillator material to form the pixelated scintillator, coating the filled at least one first aperture with an optically reflective or non-transparent material.

3. The method of claim 1 or 2, comprising:

4. The method further comprises: irradiating one or more second regions of the substrate with a second laser irradiation; performing an etch to form one or more second openings; filling the one or more second openings with an optically reflective or non-transparent material, wherein the one or more second regions are different from the plurality of first regions, and at least one second region is disposed between two adjacent first regions; 4. The method of claim 1, wherein the

5. The method further comprises:

5. A method according to any one of claims 1 to 4, comprising bending the substrate in one or two dimensions to shape the substrate according to a desired curvature.

6. 6. The method of claim 1, wherein at least one of the first laser radiation and the second laser radiation is generated by a focused pulsed femtosecond laser.

7. The method of claim 1 , wherein the plurality of first apertures are angled toward a common focal point.

8. 8. The method of claim 1, wherein the at least one scintillator material filled in the plurality of first openings has a relatively greater thickness at the center of the substrate than at the edges of the substrate.

9. 9. The method of claim 1, wherein the plurality of first openings are filled with at least two scintillator materials having different scintillator emission spectra.

10. 10. The method of claim 9, wherein the at least two scintillator materials are deposited successively in at least one of the first openings, and / or the pixelated scintillator has a plurality of scintillator elements, wherein at least one scintillator element of the pixelated scintillator has a plurality of sub-scintillator elements, and at least two sub-scintillator elements of the at least one scintillator element are filled with different scintillator materials.

11. 11. The method of claim 1, wherein the substrate comprises a glass material or a plastic material.

12. 12. A pixelated scintillator obtainable by the method of any one of claims 1 to 11, the pixelated scintillator having a plurality of first openings in a substrate that is transparent or at least partially transparent to laser radiation, the plurality of first openings in the substrate being filled with at least one scintillator material, and the plurality of first openings being angled towards a common focal point.

13. 1. A radiation detector comprising:

13. The pixelated scintillator of claim 12; a pixelated photosensitive readout sensor; A radiation detector having:

14. 14. The radiation detector of claim 13, wherein the radiation detector is a multi-layer detector having a plurality of stacked pixelated scintillators.

15. 15. A radiation detector according to claim 13 or claim 14, wherein the pixelated scintillator and the pixelated photosensitive readout sensor are constructed and arranged to form the radiation detector in a back-illuminated or a front-illuminated geometry.

16. 12. A manufacturing system for manufacturing a pixelated scintillator according to the method of any one of claims 1 to 11, comprising: an optical laser system; an etching system; a material deposition system; a control system having one or more controllers; the control system is configured to control the optical laser system to irradiate a plurality of first regions of the substrate with a first laser irradiation according to a predetermined geometry of the pixelated scintillator, thereby causing a structural modification of a material in the plurality of first regions of the substrate, such that when the substrate is subjected to etching, the etching proceeds at a higher rate in the irradiated plurality of first regions than in non-irradiated regions; the control system is configured to control the etching system to perform the etching to form a plurality of first openings in the substrate, the first openings having the predetermined geometry of the pixelated scintillator; and the control system is configured to control the material deposition system to fill the plurality of first openings with at least one scintillator material to form scintillator elements of the pixelated scintillator.

17. A computer program comprising instructions for causing a manufacturing system according to claim 16 to carry out the steps of the method according to claims 1 to 11.

18. 18. A computer readable medium storing the computer program of claim 17.

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