NL2011593C2 - Scintillator. - Google Patents

Description

FIELD OF THE INVENTION

The present invention is in the field of a scintillator.

BACKGROUND OF THE INVENTION A scintillator converts X-rays into visible light. High performance scintillators can be made of a crystalline material, such as Csl. The light can be detected by a sensor e.g. comprising arrays of diodes, a photographic plate, and a charge coupled device (CCD) plate. An image formed accordingly > is called a radiogram.

In a scintillator two main performance parameters are typically considered, namely light output performance and modulation transfer function.

The modulation transfer function (MTF) is the spatial freguency response of an imaging system or a component. It is the contrast at a given spatial freguency relative to low frequencies. The MTF is preferably as high as possible.

On a radiogram, objects having different sizes and opacity are displayed with different gray-scale values. MTF is responsible for converting contrast values of different-sized objects (object contrast) into contrast intensity levels in the image (image contrast). For general imaging, the relevant details are in a range between 0 and 2 cycles/mm, which demands high MTF values.

In summary, MTF is the capacity of the detector to transfer the modulation of the input signal at a given spatial frequency to its output. MTF is a useful measure of true or effective resolution, since it accounts for the amount of blur and contrast over a range of spatial frequencies.

In an example a prior art scintillator is grown on a substrate and has a pillar structure. Due to crystallographic limitations the pillars have a cone-like shape at the top. It has been found that often the pillar diameter is bigger at the top of the pillars compared to the bottom (substrate side) thereof. Each pillar is considered to act as sort of a wave guide for the light and helps maintaining the spatial resolution of the image, e.g. on the CCD or diode array detector.

On the scintillator pillars typically a leveling layer is applied in order to cover the top of the (Csl) pillars. It has been found that the leveling layer preferably should not penetrate in between the pillars. It is believed that this causes the decrease of MTF as light can leave the pillars and show spatial cross-talk. A problem is that when (moist sensitive) scintillating material is exposed to humid air, the scintillator efficiency starts to change and the image quality degrades over the course of time in terms of MTF and the noise level of the image. For this reason scintillating layers have to be covered with a sealing (or barrier) layer. A disadvantage of sealing layers is that upon application thereof it is difficult to maintain the spatial resolution (MTF). Typically on top of the leveling layer a barrier layer is placed. This layer prevents the penetration of moisture toward the leveling layer and scintillator layer to some extent.

The prior art barrier layers are typically not her-mitic, thereby causing degradation of the scintillator over time, e.g. in terms of MTF and output performance.

Also barrier layers are of insufficient quality, e.g. in terms of uniform coverage, uniform characteristics, layer thickness, etc. Such is partly due to inherent complexity of the scintillator, e.g. pillar like structure scintillator material .

Also prior art barrier layers are not good enough at elevated temperatures and/or elevated hygroscopicity, especially over time.

In view of the above problems there is a need for an improved scintillator which overcomes one or more of the above disadvantages, without jeopardizing functionality and advantages .

SUMMARY OF THE INVENTION

The present invention relates to an improved scintillator for X-rays according to claim 1, use of a scintillator according to claim 12, an X-ray detector comprising the present scintillator according to claim 13, and a method of producing an improved scintillator according to claim 14.

The present invention relates to use of ALD (Atomic Layer Deposition) for depositing one or more very thin layers in the range of up to 1000 nm thickness, that is up to in the order of 1000 atomic layers. Thereby a very thin (stack of) layers is provided as compared to existing solutions, which have micrometer (>1,000 nm) thick barrier layers. In an example the present moisture barrier layer can be constituted of one or more individual ALD layers of e.g. inorganic layers, such as A1203, Ti02, SiN, Si02, and similar materials.

The present barrier structure is found to be pinhole free. The present barrier has not been found to influence characteristics of the scintillator, such as MTF, negatively. The present ALD Inorganic multilayer (nanolaminate) is considered unique.

It has been found experimentally that the thickness of a layer stack affects the MTF. It is shown that the levelling layer thickness, a protective layer thickness, and a position distance each have a significant (negative) impact on the MTF of the scintillator plate. As the present barrier provides good moisture barrier properties, the thicknesses of other layers, such as the levelling layer and protective layer, which layers also provide some barrier properties, can be kept much smaller (thinner). As a result an overall performance, e.g. in terms of MTF, is much better with the present barrier .

On top of the ALD layer an extra layer for mechanical protection can be deposited such as consisting of Parylene. Parylene is the trade name for a variety of chemical vapor deposited (CVD) poly(p-xylylene) polymers, typically used as moisture and dielectric barriers. It has been found experimentally that the protective layer thickness has an impact on Noise Power Spectrum (before and after quality test). The noise power spectrum (NPS) is considered a useful metric for understanding noise content in images; the higher a value, the better. For examples of the present scintillator a value of 6.0 is considered minimal. Such a value can be achieved with the present invention, in a reliable and controlled manner.

With the present invention the applied layers can be as thin as possible and of good quality, thereby maintaining performance and providing advantages as mentioned throughout the description.

Some general aspects of Atomic layer deposition (ALD) are detailed below. It relates to a thin film deposition technique that is based on the sequential use of a gas phase chemical process. The majority of ALD reactions use two chemicals, typically called precursors. These precursors react with a surface one at a time in a sequential, self-limiting, manner. By exposing the precursors to the growth surface repeatedly, a thin film is deposited. ALD is considered a self-limiting (the amount of film material deposited in each reaction cycle is constant), sequential surface chemistry that deposits conformal thin-films of materials onto substrates. ALD film growth makes atomic scale deposition control possible. ALD is considered similar in chemistry to chemical vapor deposition (CVD), except that the ALD reaction breaks the CVD reaction into two halfreactions, keeping the precursor materials separate during the reaction. ALD can be used to deposit several types of thin films, including various oxides (e.g. AI2O3, Ti02, Sn02, ZnO, Hf02) , metal nitrides (e.g. TiN, TaN, WN, NbN), metals (e.g.

Ru, Ir, Pt), and metal sulfides (e.g. ZnS).

The growth of material layers by ALD consists of repeating the following four steps: (i) Exposure of a first precursor, typically an organometal-lic compound. (ii) Purge or evacuation of a reaction chamber to remove the non-reacted precursors and gaseous reaction by-products. (iii) Exposure of a second precursor - or another treatment to activate the surface again for the reaction of the first precursor, such as a plasma. (iv) Purge or evacuation of the reaction chamber.

Each reaction cycle adds a given amount of material to the surface, referred to as the growth per cycle. To grow a material layer, reaction cycles are repeated as many times as required for a desired film thickness. One cycle may take time from 0.5 s to a few seconds and deposit between 0.1 and 3 A of film thickness.

The present ALD-grown films are found to be extremely conformal and uniform in thickness.

Thereby the present invention provides a solution to one or more of the above mentioned problems.

Advantages of the present description are detailed throughout the description.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates in a first aspect to an improved scintillator for X-rays according to claim 1.

The present scintillator comprises a substrate layer. In an example the plate layer is selected from an aluminium plate, a fibre optic plate, and a carbon plate. It is noted, as is shown in the figures, that in case of a fibre optic plate a scintillator layer is preferably placed on the plate, whereas in case of an aluminium plate and a carbon plate a scintillator is preferably place below the plate. Aluminium is preferred if relatively high energy X-rays need to be detected, carbon is preferred when relatively low energy X-rays need to be detected. Carbon also matches well with a glass substrate. A substrate or plate typically has a thickness of 0.3-100 mm. In an example an aluminium plate has a thickness of 0.3-1.0 mm, a fibre optic plate has a thickness of 1-4 mm and a carbon plate has a thickness of 0.5-2.0 mm. In an example a plate protects a sensor, typically provided under the plate, from being damaged by X-rays. A thickness of the plate is typically adapted to the energy of X-rays being used, in a specific application or over a range of applications. A carbon plate may be provided with a reflector.

The present scintillator may find application in relatively large devices, having an area of e.g. 0.5*0.5 m2, and in relatively small devices, having an area of e.g. 1*1 cm2. Typical sizes provided are circular plates with diameters of 15 cm, 23 cm, 31 cm and 38 cm, rectangular plates with dimensions of 20*40 cm2, 44*44 cm2, 5*5 cm2, 20*1 cm2, and an octagonal plate of 5*3 cm2. In other words the present scintillator is applicable over a wide range of surface areas. The present scintillator is preferably a substantially flat scintillator.

The present scintillator layer may have a thickness of 100-3000 pm. For relatively low energy X-rays the thickness may be 100-300 pm, such as 120-200 pm, whereas for relatively high energy X-rays the thickness may be in 500-3000 pm, such as 1000-2000 pm. An X-ray energy used is typically from 1 keV (low energy) to 400 keV (high energy), such as from 10 keV-300 keV.

In an example the scintillator material is selected from crystalline Csl, Til, such as doped or undoped.Csl. It is noted that many crystalline materials and salts are (somewhat) hygroscopic, such as Csl and Til. In (high) vacuum applications hygroscopicity is often not an issue. Under typical conditions a scintillator is applied at a hygroscopicity which over time deteriorates the scintillator. Protection of the scintillator is therefore needed. The present scintillator can be applied under relatively high humidity (95% RH at 25 °C) without deterioration.

The scintillator material is preferably deposited or grown directly on the substrate. Such improves characteristics of the present scintillator, such as an improved transmission.

The scintillator material may be tuned for a given sensor, such as by doping and forming mixed crystals. For instance doping Csl with Na may provide light with a 420 nm wavelength; doping Csl with Ti may provide light with a 560 nm wavelength .

In an example the scintillator material is a pillar type structure. The length of the pillars, or likewise the thickness of the scintillator, may be varied and adapted to requirements. A characteristic of the pillars is that typically some space is left in between the pillar. Such space is important for spatial resolution of the scintillator. Also (a fraction of the) pillars tend to be somewhat broader on a top side thereof. A typical diameter if Csl pillars is from 1-20 pm, such as from 3-10 pm.

The present scintillator is characterized in that the first moisture barrier layer has a thickness of 10 nm-1000 nm. Such is considered an extremely thin layer in the field. The present barrier layer is hermetic and has a high density, that is provides a superior moisture barrier. The present barrier layer comprises two or more layers each individually having a thickness of 0.5 nm-100 nm, such as 1-50 nm, or having one or more hybrid layers, or combinations thereof. It is noted that a typical prior art layer comprises only one layer with a much larger thickness. It is also noted that de- positing a layer on a relatively rough structure, such as the present scintillator layer, is inherently complex.

In an example the first moisture barrier layer comprises a relatively large number of layers, such as 3-50 layers, preferably 5-30 layers, more preferably 10-20 layer. Especially combinations of different layers have been found to provide good characteristics, e.g. in terms of a moisture barrier being hermetic.

In an example the'first moisture barrier layer has a thickness of 20 nm- 500 nm, preferably 50 nm- 250 nm, more preferably 100 nm- 150 nm. The thickness is preferably as small as possible, e.g. in view of MTF. The thickness is also large enough to provide a good moisture barrier. It has been found that a very thin barrier layer, comprising some 15 layers, provides an excellent moisture barrier and hardly influences other characteristic of the scintillator, such as MTF. For small thicknesses no noticeable negative effect on characteristics could be observed.

In an example the first moisture barrier layer comprises layers, each layer comprising a material, individually selected from metals, such as Al, metal oxides, such as Ti02, A1203, ZnO, Si02, metal nitrides, such as TiN, Si3N4, preferably a sequence of 5-50 A1203 and Ti02 layers such as 10-20 layers. Subsequent layers preferably have a thickness of 1-10 nm. A total thickness in an example is 50-200 nm, such as 100-150 nm. The first moisture barrier layer is preferably applied on a first levelling layer.

In an example of the present scintillator the scintillator layer is covered with an adhesion layer. The adhesion layer improves characteristics of a subsequent applied levelling layer, such as coverage, and it also improves adhesion of e.g. a levelling layer, especially towards the substrate, for instance of Parylene-C. It is now possible to adhere such a levelling layer also on sides of the substrate, especially in case of a Fibre Optic Plate (FOP). It is a known problem that adhesion of Parylene-C on e.g. FOP is limited. Also various levelling layers, such as parylene, tend to peel off over time. The adhesion layer comprises a material selected from saturated linear and branched hydrosilicons (SinH2n+2) r preferably wherein n e [1,6]. The adhesion layer preferably is a silane type layer, such as monosilane and disilane. It has been found that especially silanes can be applied very well on the present scintillator material. A specific advantage of using silane is that it avoids grinding as an extra step, which on top of that may cause dirt by particles. Indirectly also characteristics of further applied layers are improved. Despite that silanes have found wide application, silanes have not been used to the knowledge of the inventors in scintillators .

The present scintillator may further comprise one or more of a levelling layer on the scintillator layer, a first protective layer, a second protective layer, and a second moisture barrier layer.

The one or more levelling layers may have a thickness which can be related to a thickness of the scintillator material. It is preferred that the levelling layer has a thickness of 1-5% of a thickness of the scintillator layer, such as 1.5-3%. In other words a relatively thin scintillator layer may have a relatively thin levelling layer, and likewise a relatively thick scintillator layer may have a relatively thick levelling layer. In an example the levelling layer has a thickness of 3-20 pm, preferably 5-15 pm, such as 8-10 pm.

It is noted that applying a barrier layer on a flat surface, such as glass, is intrinsically much easier than applying a similar layer on a rough, pillar like structure.

There rough structures preferably use a levelling layer to provide some surface flatness. Also inter-pillar space is covered. It has been found experimentally that optimal results in terms of e.g. barrier properties are achieved when a levelling layer is not too thin. A levelling layer and other layers, preferably have comparable refractive indices, such as about 1.62 for a levelling layer, and about 1.79 for a scintillator layer. Preferably the respective refractive indices are equal to a refractive index of the scintillator layer ± 20% (e.g. 1.79 ± 0.36), more preferably ± 10% (e.g. 1.79 ± 0.18).

In an example the levelling layer comprises a material selected from aromatic polymers, such as poly(p-xylylene) (parylene), such as parylene C, and parylene N. These materials have been found to provide a good coverage, that level the scintillator pillars, provide a relatively flat and smooth surface, can be applied easily, and do not or at the most slightly penetrate in between pillars.

In an example the optional second moisture barrier layer comprise layers, each layer comprising a material, individually selected from metals, such as Al, metal oxides, such as Ti02, AI2O3, ZnO, S1O2, metal nitrides, such as TiN, S13N4, preferably a sequence of 5-50 Al and Ti02 layers such as 10-20 layers. Subsequent layers preferably have a thickness of 1-10 nm. A total thickness in an example is 50-200 nm, such as 100-150 nm. Characteristics of the first and second moisture barrier layer may be selected independently. The second moisture barrier layer is preferably applied on a protective layer.

In an example the first and optional second protective layer comprises a material, each individually, selected from aromatic polymers, such as poly(p-xylylene) (parylene), such as parylene C, and parylene N. These materials have been found to provide a good coverage, that protect the scintillator pillars from mechanical impact, provide a relatively flat and smooth surface, and can be applied easily. These protective layers are typically applied in a thickness comparable to that of the levelling layer, preferably somewhat thinner.

The present scintillator is typically used in combination with one or more of an image detecting device, an image forming device, an (image)'' amplifier, an image inten-sifier, an image processor, such as a computer, and a monitor .

In a second aspect the present invention relates to a use of the present scintillator for non-destructive applications, such as non-destructive testing, for (para)medical applications, such as one or more of dental inspection, such as intra oral and extra oral inspection, mammography, thorax inspection, and orthopaedics.

For medical applications the use typically relates to radiography. A radiograph is an X-ray image of an object wherein heavier parts, such as bones, or lighter parts, such as lungs, can be made visible. A patient is subjected to X-ray radiation and an image is made. Typically radiographs are used for detection of pathology and diseases. Examples are thorax inspection, abdominal inspection, gallstones inspection, kidney stones inspection, orthopedics inspection and mammography.

Also dental radiography is commonly used.

For each diagnoses a suitable X-ray energy is determined .

In some applications an image is taken in combination with a contrast agent.

An advanced technique relates to computed tomography or CT .

Also real-time moving images of internal structures of a patient may be obtained. Therein use can be made of a fluorescent screen.

In a third aspect the present invention relates to an X-ray detector comprising the present scintillator.

In a fourth aspect the present invention relates to a method of producing an improved scintillator according to the invention, comprising the steps of: providing a substrate plate layer, and a scintillator layer, and depositing a first hermetic high density moisture barrier layer by using atomic layer deposition.

In an example the present method further comprises the step of depositing an adhesion layer, preferably a silane adhesive layer.

The invention is further detailed by the accompanying figures and examples, which are exemplary and explanatory of nature and are not limiting the scope of the invention. To the person skilled in the art it may be clear that many variants, being obvious or not, may be conceivable falling within the scope of protection, defined by the present claims.

SUMMARY OF FIGURES

Figure 1 shows a SEM image of a pillar structure.

Figure 2-8 show schematic cross-sections of a scintillator .

DETAILED DESCRIPTION OF FIGURES

In figure 1 a SEM image of a pillar structure is shown. Clearly visible are tops of many pillars, typically Csl pillars. A cross section diameter of a pillar is in the order of 7-8 pm. In between pillars an open space is typically present .

In figure 2 a schematic cross-section of a scintilla- tor is given. Therein the following layers are identified: 1 = Substrate; 2 = Scintillator layer; 4 = Leveling layer; 5 = Moisture barrier; and 6 = Protective layer. The leveling and protective layer are typically formed from Parylene-C.

In figure 3 a schematic cross-section of a scintillator is given. Therein the following layers are identified: 1 = Aluminum substrate; 2 = Scintillator layer; 3 = adhesion layer; 4 = Leveling layer; 5 = Moisture barrier; and 6 = Protective layer.

In figure 4 a schematic cross-section of a scintillator is given. Therein the following layers are identified: 1 = Carbon substrate; 2 = Scintillator layer; 3 = adhesion layer; 4 = Leveling layer; 5 = Moisture barrier; 6 = Protective layer; and 7 = Reflector.

In figure 5 a schematic cross-section of a scintillator is given. Therein the following layers are identified: 1 = FOP substrate; 2 = Scintillator layer; 3 = adhesion layer; 4 = leveling layer; 5 = moisture barrier; and 6 = protective layer .

In figure 6 a schematic cross-section of a scintillator is given. Therein the following layers are identified: 1 = FOP substrate; 2 = Scintillator layer; 3 = adhesion layer; 4 = Leveling layer; 5 = Moisture barrier; 6 = Protective layer; 8 = Second moisture barrier; and 9 = Second protective layer.

In figure 7 a schematic cross-section of a scintillator is given. Therein the following layers are identified: 1 = FOP substrate; 2 = Scintillator layer; 6 = Protective layer; and 10 = Sensor.

In figure 8 a schematic cross-section of a scintillator is given. Therein the following layers are identified: 1 = Aluminum substrate; 2 = Scintillator layer; 6 = Protective layer; and 10 = Sensor.

The figures are further detailed in the description and in the experiments below.

EXAMPLES/EXPERIMENTS

The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying examples and figures.

Experiments with different thicknesses of leveling layer, barrier layer and protective layer have been performed.

It has been identified that the thickness of the layer stack affects the MTF: a thinner layer improves the MTF. It is shown that the levelling layer thickness and likewise the protective layer thickness have a significant impact on the MTF of the scintillator plate. In an example the MTF drops linear ly from about 59% (0 1 lp/mm) at a (combined) thickness of 1 pm to about 53% at a thickness of 20 pm (best fit: MTF=-0.4 thickness + 59.5%) .

Experiments in view of the image noise have been performed. Noise is described by Noise Power Spectrum (NPS). Noise power spectrum displays the frequency distribution of the noise across the spatial spectrum and it shows the shift in the noise spectrum that is the cause of the change in appearance of the total noise. A standard NPS measurement is given in IEC 62220-1 (ed. 1, 2003). In the example the standard NPS measurement is normalized, by dividing by the average of linearized data, and by taking a -10log of the average NPS.

It is noted that in principle a single barrier layer may be used. Although such a structure (with a single inorganic layer) can keep the MTF value at a sufficient level, the image noise power increases over the course of time (under moist air). On the contrary, inorganic multilayer structures (nanolaminate) maintain the noise power of the image at a sufficiently low level. It has been found experimentally that ALD provides a robust inorganic barrier e.g. compared to other techniques (like CVD, PECVD or sputtering) . It has been found that if a same thickness is used for various inorganic layers, in comparison an ALD layer shows more robust barrier performance. Also a film density is higher.

It is noted that ALD layer performance (in terms of water vapor transmission rate) is as good as 10“3 (g/m2/day). In order to reach this value by using another technique, relatively thick and/or complex structures are needed. A use of ALD now makes it possible to use a much thinner protective and/or levelling layer. The total thickness of the stack of layers is thinner and therefore the achieved MTF is higher.

In table 1 it is shown that a thicker leveling layer (parylene) gives a higher drop in initial MTF. Further it is shown that a thicker leveling layer is needed for a thicker Csl layer. A 3 pm leveling layer on top of a 600 pm Csl layer is too thin to form a good moisture barrier, resulting in a larger MTF drop (-20.4 %). A 3 pm leveling layer on top of a 120 pm Csl layer provides sufficient results.

Table 1: Impact of Csl thickness and leveling layer thickness on MTF (before and after climate testing (40 °C and 93% RH)) .

As a substrate a FOP was used.

The impact of parylene thickness on MTF before and after climate testing is further investigated. In an example an aluminum substrate was used with a 600 pm Csl layer. It is shown that the initial MTF drops from about 60% (at 1 lp/mm) for a 1 pm parylene layer to 50% (at 1 lp/mm) when a 20 pm parylene layer is used. It is also shown that a thicker parylene layer gives a smaller MTF drop after climate testing (as above) (likewise form about 9% for a 1 pm parylene layer to 42% (at 1 lp/mm) when a 20 pm parylene layer is used).

It has been identified experimentally that if thicker CsI:Tl layers are used, the leveling layers also have to be thicker. It is believed that such relates to covering the gaps between the cone-like pillars which give a larger surface roughness of the CsI:Tl.

By use of ALD, which has been found to seal pinholes very effectively, some examples of scintillator Csl thickness and leveling layer thickness are: a) CsI:Tl Thickness: 400pm; leveling layer thickness: typically 8pm; b) CsI:Tl Thickness: 600pm; Leveling Layer thickness: '«lOpm or 12pm; c) Thinner Csl (120pm to 150 pm) can have about 3 pm thick leveling layer.

In summary it has been found that use of ALD makes it possible to have a well insulating stack of layers on top of Csl which can be thinner than with other type of non-ALD barrier layers, which improves the MTF.

It should be appreciated that for commercial application it may be preferable to use one or more variations of the present system, which would similar be to the ones disclosed in the present application and are within the spirit of the invention.

Claims (15)

An improved X-ray scintillator comprising a substrate plate layer, a signal layer, and a first moisture barrier layer, characterized in that the first moisture barrier layer has a thickness of 10 nm-1000 nm, is hermetic and has a high density, and comprises two or more layers each of which individually has a thickness of 0.5 nm-100 nm, or with one or more hybrid layers, or combinations thereof. The scintillator of claim 1, wherein the plate layer is selected from an aluminum plate, an optical fiber plate, and a carbon plate. The scintillator according to claim 2, wherein the signal generator material is selected from crystalline Csl, and Til, such as doped or not doped Csl. The scintillator according to any of claims 1-3, wherein the signal generator material has a column type structure. A scintillator according to any one of claims 1-4, wherein the first moisture barrier layer comprises 3-50 layers, preferably 5-30 layers, more preferably 10-20 layers, and / or wherein the first moisture barrier layer has a thickness of 20 nm-500 nm has, preferably 50 nm-250 nm, more preferably 100 nm-150 nm. The scintillator according to any one of claims 1-5, wherein the seintillator layer is covered with an adhesive layer. The scintillator of any one of claims 1-6, further comprising one or more of a leveling layer on the seintillator layer, a first protective layer, a second protective layer, and a second moisture barrier layer, and / or wherein the leveling layer has a thickness of 1- Has 5% of a thickness of the signal layer, such as 1.5-3%, such as with a thickness of 3-20 µm, preferably 5-15 µm, such as 8-10 µm. The scintillator of any one of claims 1-7, wherein the first and optional second moisture barrier layers comprise layers, each layer comprising a material selected individually from metals such as Al, metal oxides such as TiCg, Al2O3, ZnO, S1O2, metal nitrides such as TiN , S13 N4, preferably a sequence of Al2 O3 and TiCg layers. The scintillator according to any of claims 1-8, wherein the adhesive layer comprises a material selected from saturated linear and branched hydrosilicones (SinH2n + 2)? wherein preferably n e [1.6], such as monosilane and disilane. The scintillator according to any of claims 7-9, wherein the leveling layer comprises a material selected from aromatic polymers, such as poly (p-xylylene) (parylene), such as parylene C and parylene N. The scintillator of any one of claims 7-10, wherein the first and optional second protective layer comprises a material, each independently selected from aromatic polymers, such as poly (p-xylylene) (parylene), such as parylene C and parylene N. Use of a scintillator according to any of claims 1-11 for non-destructive applications, such as non-destructive testing of (para) medical applications, such as one or more of dental inspection, such as intra oral and extra oral inspection, mammography, thorax inspection, and orthopedics. An X-ray detector comprising a scintillator according to any one of claims 1-11. A method for producing an improved scintillator according to any of claims 1 to 11, comprising the steps of providing a substrate plate layer, and a seintillator layer, and depositing a first hermetic high-density moisture barrier layer using atomic layer deposition . The method of claim 14, further comprising the step of depositing an adhesive layer, preferably a silane adhesive layer.