Storage phosphor layer and system and method for erasing same

An apparatus (1) for erasing a storage phosphor layer (2) with a holding plane (7) in which the storage phosphor layer (2) lies or can be moved, a radiation source (8, 9, 10) for irradiating the storage phosphor layer (2) with erasing radiation which is suitable for erasing the storage phosphor layer (2), and a reflector (11; 29, 30) for reflecting erasing radiation in the direction of the holding plane (7). In order to increase the erasing efficiency, provision is made such that the reflector (11; 29, 30) is arranged and/or designed such that it reflects erasing radiation, which is reflected by the storage phosphor layer (2), in the direction of the storage phosphor layer (2), and the radiation source (8, 9, 10) is disposed on a base (33; 48, 49), the base (33; 48, 49) being disposed closer to the holding plane (7) than at least part of the reflector (11; 29, 30).

RELATED APPLICATIONS

This application claims priority to European Patent Application Nos. EP06119938.6 filed on Aug. 31, 2006 and EP06125512.1, filed on Dec. 6, 2006, both of which are incorporated herein by reference in their entirety.

This application relates to U.S. Application Publication No. US 2008/0054200 A1, published on Mar. 6, 2008 titled “Storage Phosphor Layer and System and Method for Erasing Same,” by Dr. Andreas Bode et al., and U.S. Application Publication No. US 2008/0054201 A1, published on Mar. 6, 2008titled, “Storage Phosphor Layer and System and Method for Erasing Same,” by Dr. Andreas Bode et al.

BACKGROUND OF THE INVENTION

Apparatuses for erasing a storage phosphor layer are used in particular in the field of computer radiography (CR) for medical purposes. A picture is produced of an object, for example a patient or a body part of the patient, by means of X-ray radiation which is stored in a storage phosphor layer as a latent picture. Therefore, this type of X-ray picture contains X-ray information about the object. In order to read out the X-ray information stored in the storage phosphor layer, the storage phosphor layer is stimulated by means of an irradiation device. As a result of this stimulation, the storage phosphor layer emits radiation which has an intensity corresponding to the X-ray information stored in the storage phosphor layer. The radiation emitted by the storage phosphor layer is collected by a detection device and converted into electrical signals, which contain an image of the X-ray information. The electrical signals are further processed and the X-ray information stored in the storage phosphor layer is then made visible. The X-ray information can be displayed directly on a monitor, for example, or be written onto a photographic X-ray film by means of a printer used especially for X-ray pictures.

After reading out the X-ray information from the storage phosphor layer, remains of the latent picture remain in the latter. Furthermore, noise information can be stored in the layer. In order to be able to use the storage phosphor layer for further X-rays, it is therefore erased. For this procedure, a radiation source is used that emits erasing radiation onto the storage phosphor layer. An apparatus for erasing a storage phosphor layer is known from U.S. Pat. No. 7,075,200 B2. As a radiation source this erasing apparatus contains two lines with light emitting diodes, disposed parallel to one another, for emitting the erasing radiation and which are disposed on cooling elements made of aluminum. For erasure, the storage phosphor layer is pushed in a direction of conveyance through a ray path of the lines of light emitting diodes. The two lines of light emitting diodes are integrated into reflectors which are spaced apart from one another. The reflectors serve to reflect erasing radiation emitted by the light emitting diodes in the direction of the storage phosphor layer. The reflectors are respectively formed by means of two reflector surfaces which are disposed to either side of the lines of light emitting diodes in the direction of conveyance. The reflector surfaces adjoin the cooling elements with obtuse inner angles so that the reflectors open from the cooling elements in the direction of the storage phosphor layer.

SUMMARY OF THE INVENTION

It is the object of the present invention to enable high efficiency when erasing a storage phosphor layer.

With the apparatus according to the invention provision is made such that the reflector is arranged and/or designed such that it reflects back erasing radiation which is reflected by the storage phosphor layer in the direction of the storage phosphor layer, and the radiation source is disposed on a base, the base being disposed closer to the holding plane than at least part of the reflector. The system according to the invention includes the apparatus according to the invention and a storage phosphor layer.

The knowledge which forms the basis of the invention is that the storage phosphor layer has a high degree of reflection due to which a large part of the erasing radiation with which the storage phosphor layer is irradiated is reflected by the latter without being used and so does not contribute to the erasure of undesired picture information stored in the storage phosphor layer.

According to the invention, the erasing radiation reflected by the storage phosphor layer is captured by the reflector and reflected back again in the direction of the storage phosphor layer. This reflection can be directed (specular) or diffuse. In this regard, the reflector is designed with an appropriate shape and size and/or is an appropriate distance away from the storage phosphor layer.

The erasing radiation reflected back by the reflector can therefore also contribute to erasure of the storage phosphor layer. In this way, the efficiency of the erasure is substantially improved. Furthermore, the power requirement is less, and this leads to less lost heat and an increase in lifespan.

Due to the positioning of the radiation source on a base according to the invention, it is moreover guaranteed that very little of the erasing radiation reflected by the reflector, and which has already previously been reflected by the storage phosphor layer in the direction of the reflector, is reflected by the reflector into the radiation source. In this way undesired reabsorption of erasing radiation, which is reflected by the storage phosphor layer and by the reflector, in the radiation source is avoided, and so efficiency losses are greatly reduced.

The base is preferably a component part of the reflector and is formed by raising the reflector in the direction of the holding plane. Preferably, the reflector is formed together with the base from one piece, in particular a reflective metal sheet. The actual reflector surfaces of the reflector advantageously adjoin the base directly here.

Advantageously, the radiation source has a plurality of individual light sources, such as e.g. light emitting diodes, which are disposed in a radiation plane that extends parallel to the holding plane.

In one advantageous embodiment of the invention, the base is formed, reflectively, on the side facing towards the holding plane. In this way, it can be guaranteed that the base also reflects erasing radiation that reflected by the storage phosphor layer back in the direction of the storage phosphor layer. This further increases the efficiency when erasing the storage phosphor layer.

In a further advantageous embodiment, the base is in particular curved in form in the direction of the holding plane. In relation to the holding plane, the base is convex in form. In one particularly preferred embodiment of the invention, the base has at least one indentation in which the radiation source is formed. Particularly advantageously, the base is disposed closer than the whole reflector to the holding plane. These advantageous embodiments enable particularly good protection of the radiation source from erasing radiation reflected by the reflector taken individually and in particular as a whole.

Preferably, the reflector has a reflector surface curving away from the holding plane. In relation to the holding plane, the reflector is concave in form. In this way the reflected erasing radiation, particularly well directed in the direction of the storage phosphor layer, can be reflected without hitting the radiation source.

In one advantageous embodiment of the invention, the reflector has a flat reflector surface that extends in particular parallel to the holding plane. This type of reflector form can reliably collect reflected erasing radiation and reflect it back to the storage phosphor layer. This form of reflector can be manufactured inexpensively and can be compact in design.

In a further advantageous embodiment, the reflector has a reflector surface with a structure. With this type of structure the efficiency of the erasure can be even further increased. The structure can in particular be fluted, or in the form of a roof or saw teeth and/or triangular etc.

In one particularly preferred embodiment of the invention, the structured reflector surface is retroreflective in form so that it reflects back at least part of the erasing radiation to points of the storage phosphor layer at which it was previously reflected by the storage phosphor layer. This type of retroreflective reflector surface guarantees particularly even erasure of the storage phosphor layer. At those points that have reflected a lot of erasing radiation, a lot of erasing radiation is also reflected back. The retroreflective reflector surface can in particular be designed in the form of a so-called “cat's eye”, and be inserted as a film. This is particularly space saving and cost-effective.

Particularly preferably, a drive for producing a relative movement between the holding plane and the radiation source is provided. This simply enables even production of the relative movement and efficient erasure of the storage phosphor layer.

Particularly advantageously, the reflector has at least two reflector surfaces so that the reflector, considered in the direction of the relative movement, is formed to either side of the radiation source. In this way, a particularly large amount of erasing radiation can be collected and reflected back.

In one particularly preferred embodiment of the invention, the reflector is formed mirror- or reflective- symmetrically in the direction of the relative movement, an axis of symmetry extending at right angles to the direction of the relative movement, and considered in the direction of the relative movement, centrally through the radiation source. By means of this type of reflector a large quantity of reflected erasing radiation can be collected to both sides of the radiation source and be reflected back to the storage phosphor layer.

In one advantageous embodiment of the invention, a width of the reflector in the direction of the relative movement is at least ten times as great as a smallest distance between the reflector and the holding plane. By means of this dimensioning of the reflector with a large width in the direction of the relative movement and a small distance from the holding plane, it can in particular be guaranteed for the storage phosphor layer that a large part of erasing radiation reflected or dispersed by the storage phosphor layer can be captured or collected and reflected back again in the direction of the storage phosphor layer.

Particularly advantageously, the radiation source has at least two lines with light emitting diodes extending at right angles to the direction of the relative movement and parallel to the holding plane. In this way, a sufficiently high intensity of erasing radiation can be produced, the power consumption of the light emitting diodes being particularly low.

Preferably, the at least two lines with light emitting diodes are integrated into the base. A distance between the at least two lines is smaller than or equal to a distance between the light emitting diodes and the holding plane. Due to this, the erasing apparatus can be particularly compact in design. Furthermore, the erasing radiation emitted by the lines of light emitting diodes can be emitted, particularly well directed, to the storage phosphor layer.

Particularly preferably, a separate reflector and a separate base are respectively allocated to the at least two lines with light emitting diodes. The light emitting diodes of the respective lines further emit radiation, in particular in a narrow-band wavelength range different to that of the light emitting diodes of the other lines. The reflectors are designed in particular so that they contribute to separation of the erasing radiation with the different wavelength ranges emitted by the different lines of light emitting diodes. In this way particular spectral ranges can be prevented from mutually effecting or disrupting one another. The wavelength ranges can advantageously be chosen such that wavelengths which do not contribute to the erasure of the type of storage phosphor layer used are not available. Due to this, the filtering out of these wavelengths, which would otherwise be necessary, is not necessary. Furthermore, particularly good erasing efficiency is achieved.

Preferably, the at least two lines with light emitting diodes are disposed one behind the other in the direction of the relative movement such that when implementing the relative movement in order to erase the storage phosphor layer, short wavelength or shortwave erasing radiation hits the storage phosphor layer before long wavelength or longwave erasing radiation. In particular here, blue erasing radiation is directed at the storage phosphor layer before red erasing radiation. In this way particularly good erasing efficiency is guaranteed.

Preferably, an intensity of the longwave erasing radiation is greater than an intensity of the shortwave erasing radiation. In particular, a ratio of blue to red erasing radiation can be chosen such that 66% of the erasing radiation is red and 33% of the erasing radiation is blue erasing radiation. This guarantees even better erasing efficiency.

Particularly preferably, a further reflecting surface positioned opposite the reflector, as considered in the direction at right angles to the direction of the relative movement, is provided for reflecting erasing radiation. The further reflecting surface is formed such that it reflects the erasing radiation directionally (specularly) or diffusely, in one example. Advantageously, by means of this further reflecting surface, at the start and/or at the end of the erasing process, i.e. when the ray path of the radiation source is not or not fully directed at the storage phosphor layer, the erasing radiation emitted by the radiation source can be reflected by the further reflecting surface in the direction of the reflector. The erasing radiation reflected by the further reflecting surface and which in particular has not yet reached the storage phosphor layer, can therefore be directed by the reflector towards the storage phosphor layer. In particular, the front and, if appropriate, the rear edge of the storage phosphor layer can therefore be erased with a high level of efficiency.

Preferably, the further reflecting surface is disposed on the side of the holding plane facing away from the reflector. In this way, it can be particularly well guaranteed that erasing radiation not hitting the storage phosphor layer is reflected by the further reflecting surface so as to then be reflected by the reflector in the direction of the storage phosphor layer.

Preferably, front surfaces and/or side surfaces of the reflector are reflective in design. In this way, erasing radiation reflected by the storage phosphor layer can be collected even better and more efficiently and be reflected back in the direction of the storage phosphor layer.

Preferably, the storage phosphor layer of the system according to the invention has a degree of reflection for the erasing radiation of greater than or equal to 70%, and in particular greater than or equal to 80%. The erasing apparatus according to the invention can be used particularly efficiently for storage phosphor layers with this high level of reflection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a first exemplary embodiment of an erasing apparatus1which has been constructed according to the principles of the present invention for erasing X-ray information which is stored in a storage phosphor layer2of a storage phosphor plate3. The storage phosphor plate3has a carrying layer4on which the storage phosphor layer2is placed. The storage phosphor layer2is preferably made up of a plurality of storage phosphor particles which serve to store the X-ray information. The carrying layer4is preferably 1-2millimeters (mm) thick. Here, the storage phosphor plate3does not form part of the erasing apparatus1, but is pushed or inserted into the erasing apparatus1from the outside, in one example. Within the erasing apparatus1, the storage phosphor plate3is moved by means of a drive5in a direction of conveyance6, which is represented by an arrow. The storage phosphor plate3is moved within the erasing apparatus1in a holding plane7and can be moved within this holding plane7. Below the holding plane7, there is a support18on which the storage phosphor plate3lies and be moveably guided.

The erasing apparatus1contains a radiation source8for emitting erasing radiation. The radiation source8here has two lines of light emitting diodes9and10disposed parallel to one another. The lines of light emitting diodes9,10each contain a plurality of light emitting diodes disposed next to one another. The lines of light emitting diodes9,10extend over the whole length of the storage phosphor layer2. In the illustration according toFIG. 1, the length of the storage phosphor layer2extends at right angles to the direction of conveyance6and in the direction of the plane of the drawing sheet. The width of the storage phosphor layer2extends in the direction of conveyance6. The lines of light emitting diodes9,10are disposed on a level base33that extends parallel to the holding plane7. By means of the drive5, the storage phosphor layer2is conveyed past the lines of light emitting diodes9,10with even conveyance speed in the direction of conveyance6. In this way, the storage phosphor layer2passes through the ray paths of the lines of light emitting diodes9,10. Alternatively, it is also possible to convey the radiation source instead of the storage phosphor plate3, the storage phosphor plate3is then not moved in the erasing apparatus1. In both cases, a relative movement is implemented between the radiation source8and the storage phosphor layer2lying in the holding plane7, which here extends in the direction of the arrow for the direction of conveyance6.

When conveying the storage phosphor plate3, the erasing light emitted by the light emitting diodes of the lines of light emitting diodes9,10hits the storage phosphor layer2. Part of the erasing light penetrates into the storage phosphor layer2and erases the X-ray information remaining in the latter following a read-out and, if applicable, any noise which is present. Since the storage phosphor layer2has a degree of reflection of at least 70%, and in particular of at least 80% for the erasing light, a large part of the erasing light is reflected by the storage phosphor layer2, without contributing to the erasure.

In order to achieve a high level of efficiency and a high degree of effectiveness when erasing, the erasing apparatus1has a reflector11. In the present exemplary embodiment, the reflector11has two level reflector surfaces12and13extending parallel to the holding plane7and the storage phosphor layer2. Considered in the direction of conveyance6, the reflector surfaces12,13are disposed to either side of the base33and are advantageously equal in size. However, it is also possible to provide just a single reflector surface on one of the sides of the base33. Furthermore, it is possible to design one of the two reflector surfaces12,13to be smaller than the other.

According to the invention, the base33is disposed closer by a distance34to the holding plane7than the reflector surfaces12,13. In the present first exemplary embodiment the base33is therefore disposed closer than the whole reflector11with its reflector surfaces12,13to the holding plane7. The reflector surfaces12,13are connected to the base33by connection surfaces38and39.

The reflector surfaces12,13and the base33respectively extend over the whole length of the storage phosphor layer2. Considered in the direction of conveyance6they extend collectively over a width14of the radiation source8. A smallest distance15of the reflector11with its reflector surfaces12,13is that from the surface of the storage phosphor layer2located in the holding plane7. The width14is at least ten times greater than the smallest distance15.

The radiation source8and in particular the reflector11are mirror-symmetrical in form in the direction of conveyance6. Here, an axis of symmetry16extends at right angles to the direction of conveyance6, and in relation to the width14, centrally through the radiation source8. In the present exemplary embodiment the axis of symmetry16therefore extends between the two lines of light emitting diodes9,10.

The two lines of light emitting diodes9,10are integrated centrally into the base33here. A distance17between the two lines of light emitting diodes9,10is advantageously smaller than or equal to a distance32between the light emitting diodes and the storage phosphor layer2lying in the holding plane7.

On their surfaces facing towards the storage phosphor layer2, the reflector surfaces12,13have reflecting layers which are highly reflective for erasing light reflected by the storage phosphor layer2. The same applies in the present exemplary embodiment to the base33which is provided with a reflective layer40on its surface facing in the direction of the holding plane7, and the connection surfaces38,39. By means of these reflective layers of the reflector surfaces12,13and the base33, erasing light, which is reflected or dispersed by the storage phosphor layer2, is reflected back in the direction of the storage phosphor layer2. Due to this re-reflection, it is possible for the erasing light to now penetrate into the storage phosphor layer2in order to erase the X-ray information.

On its front face side, as considered in the direction of conveyance6, the radiation source8includes a reflection surface35, and on its rear face side, as considered in the direction of conveyance6, a reflection surface36. On its side edges the radiation source has further reflection surfaces of which a further reflection surface37is shown inFIG. 1. The face-side and side reflection surface35-37include reflective layers, in particular on their inwardly facing surfaces.

The individual light emitting diodes9,10have a housing which, in the exemplary embodiment ofFIG. 1shown, is characterized by a rectangular cross-section. On the housing, there is a transparent region for the emitted erasing light which is shown in the illustrated example by a round dome. A light-emitting semiconductor is disposed between the housing and the transparent region. The individual light emitting diodes9,10are preferably attached to the base33so that, on one hand, the housing of the light emitting diodes10is covered by the reflective layer40located on the base33from the side facing towards the storage phosphor layer2, and, on the other hand, the light-emitting semiconductor lies above the reflective layer40, i.e. on the side facing towards the storage phosphor layer2. In this way a high light output of the light emitting diodes9,10is achieved with at the same time a high level of re-reflection of the erasing light reflected by the storage phosphor layer2.

The erasing apparatus1has a further reflection surface31which is positioned opposite the reflector surfaces12,13and the base33, as considered in a direction at right angles to the direction of conveyance6. The reflection surface31is designed to reflect erasing light that has been emitted by the radiation source8. If applicable, further erasing light reflected by the reflection surface31has furthermore already been reflected by the storage phosphor layer2, the reflector surfaces12,13and/or the base33. In order to reflect erasing light, the reflection surface31is in particular placed on the side of the support18facing towards the radiation source8, i.e. on the side of the holding plane7facing away from the reflector11. The reflection surface31is advantageously applied to the support18as a thin layer. The reflection surface31is therefore arranged such that the storage phosphor plate3is conveyed between the radiation source8and the reflection surface31. The reflection surface31reflects the erasing light to the reflector11directionally (specularly) or diffusely. Here, the reflection surface31is advantageously as wide in the direction of conveyance6as the reflector11with its reflector surfaces12,13and the base33. In this way, it can advantageously be guaranteed that forms of the reflection surface31and the reflector11and the base33correspond particularly well to one another. A particularly large quantity of erasing radiation that is emitted by the radiation source8is reflected by the reflection surface31and a large quantity of this reflected erasing radiation is reflected by the reflector11and the layer40of the base33in the direction of the storage phosphor layer2. In this way, particularly good erasing efficiency is achieved.FIG. 1shows the storage phosphor plate3inserted into the erasing apparatus1. Advantageously, the reflection surface31guarantees that the erasing light emitted by the radiation source8then also contributes to the erasure with a high degree of effectiveness if the storage phosphor plate3is still not fully located within the erasing apparatus1. In particular, it is guaranteed that the leading edge of the storage phosphor layer2is erased with increased efficiency. The same applies when the storage phosphor plate3is drawn out of the erasing apparatus1. For erasing the storage phosphor layer2mit is alternatively possible to leave the storage phosphor plate3in the erasing apparatus1and to convey the radiation source8together with the reflector11and the reflection layer31positioned opposite along the storage phosphor plate3.

FIG. 2shows a perspective illustration of part of the erasing apparatus1according toFIG. 1for clarification. One can clearly see the width of the lines of light emitting diodes9and10in the longitudinal direction of the erasing apparatus1.

FIG. 3shows a second exemplary embodiment of the erasing apparatus1according to the invention. The storage phosphor plate3is not shown here. The support18is shown over which the holding plane7for holding and moving the storage phosphor plate3is located. The reflector11has two reflector surfaces19and20. The reflector surfaces19,20each have a structure that corresponds substantially to an isosceles triangle. These reflector surfaces19,20structured in a triangular shape are open in the direction of the holding plane7. The intersection points of the short sides with the long sides of the reflector surfaces19,20are spaced further apart from the holding plane7than the base33extending parallel to the holding plane7. Therefore, the base33is disposed closer to the holding plane7than a part of the reflector11. In the direction of conveyance6, the base33has a width41which is 42 millimeters (mm).

FIG. 4shows a top view of the lower side of the radiation source8according toFIG. 3. One can see the parallel arrangement of the light emitting diodes of the two lines of light emitting diodes9,10. The radiation source8extends over a length42, which is at least as great as the longitudinal extension of the storage phosphor layer2. For further clarification,FIG. 5shows a perspective illustration of the erasing apparatus1according to the second exemplary embodiment according toFIGS. 3 and 4.

FIG. 6shows a third exemplary embodiment of the erasing apparatus1according to the invention. Here, the radiation source8has a reflector11with groove-shaped reflector surfaces21and22. These groove-shaped reflector surfaces21and22are designed such that they curve away, starting at their connection points with the base33, from the holding plane7for the storage phosphor layer3. In this exemplary embodiment, the base33is therefore also closer to the holding plane7than a part of the reflector surfaces21,22. For further clarification,FIG. 7shows a perspective illustration of the erasing apparatus1according to the third exemplary embodiment according toFIG. 6.

FIG. 8shows a fourth exemplary embodiment of the erasing apparatus1according to the invention. InFIG. 8, the storage phosphor plate3is shown inserted into the erasing apparatus1. The base33, on which the two lines of light emitting diodes9,10are disposed, is offset further from the holding plane7in comparison with the second exemplary embodiment according toFIG. 3. The reflector11corresponds largely to that of the second exemplary embodiment according toFIG. 3and has two reflector surfaces23and24, which are disposed to either side of the base33, as considered in the direction of conveyance6. The reflector surfaces23,24each have a structure that substantially corresponds to an irregular triangle, as is also the case with the reflector surfaces19,20. In addition to this triangular structure, the reflector surfaces23,24have further reflection surfaces25and26. These further reflection surfaces25,26extend at an angle from the holding plane7on the nearest edges27and28of the triangular structure away from the holding plane7in the direction of the base33, and finally hit the latter. In this way connections are established between the reflector surfaces23,24and the base33. The lines of light emitting diodes9,10are disposed opposite the edges27,28in a type of indentation. In this embodiment therefore, the lines of light emitting diodes9,10are particularly well protected from radiation that is reflected by the reflector surfaces23,24in the direction of the holding plane. However, in this fourth exemplary embodiment too the base33is positioned closer to the holding plane7than a part of the reflector surfaces23,24.

FIG. 9shows a fifth exemplary embodiment of the erasing apparatus1according to the invention. The support18, above which the holding plane7for holding and moving the storage phosphor plate3is located, is illustrated. The erasing apparatus1contains the reflector11. The latter has two reflector surfaces43and44, which extend parallel to the holding plane7and the support18and are disposed to either side of the base33. The reflector surfaces43,44each have a structure that is substantially triangular in form here, similar to fine saw teeth. By means of this structure, a retroreflective profile of the reflector surfaces43,44is created. This means that the retroreflective reflector surfaces43,44advantageously reflect back at least part of the erasing radiation at points of the storage phosphor layer at which they were previously reflected by the storage phosphor layer. The base33is disposed closer to the holding plane7than the reflector surfaces43,44. The distance34between the base33and the reflector surfaces43,44is bridged by the connection surfaces38and39.

FIG. 10shows a sixth exemplary embodiment of the erasing apparatus1according to the invention. Here, the reflector11, like that of the first exemplary embodiment according toFIG. 1, has the level reflector surfaces12,13that are disposed to either side of the base33. The base33is disposed closer to the holding plane7than the reflector surfaces12,13. The base33is connected to the reflector surfaces12,13by connection surfaces45and46. Unlike the level and vertically extending connection surfaces38,39of the first exemplary embodiment according toFIG. 1, the connection surfaces45,46are curved in the direction of the holding plane7. Moreover, the two lines of light emitting diodes9,10are positioned in an indentation or recess47in the base33. In this way, the lines of light emitting diodes9,10are particularly well protected from being erasing radiation reflected into them.

FIG. 11shows a seventh exemplary embodiment of the erasing apparatus1according to the invention into which the storage phosphor plate3is inserted. In this seventh exemplary embodiment the radiation source8includes the two lines of light emitting diodes9,10, which have their own reflectors and are disposed on bases separated from one another. The line of light emitting diodes9is disposed on a base48and integrated into a reflector29. The line of light emitting diodes10is disposed on a base49and integrated into a reflector30. The two bases48,49and the two reflectors29,30are spaced apart and separated from one another in the direction of conveyance6. In this way the erasing radiation emitted by the lines of light emitting diodes9,10hits the storage phosphor layer2located in the erasing apparatus1separately.

The lines of light emitting diodes9,10emit erasing radiation in different wavelength ranges. The line of light emitting diodes9emits erasing radiation in the blue wavelength range, and the line of light emitting diodes10in the red wavelength range. In this way good “color separation” and so a high level of erasing efficiency can advantageously be achieved.

Therefore, in the direction of conveyance6of the storage phosphor plate3first of all blue and then red erasing radiation hits the storage phosphor layer2. Furthermore, the intensity of the long wavelength or longwave, red erasing radiation is greater than the intensity of the short wavelength or shortwave, blue erasing light.

The intensity portion of the red erasing radiation is advantageously approx. 66% here, and the intensity portion of the blue erasing light is approx. 33%. In this way particularly good erasing efficiency is guaranteed.

The reflectors29,30each have reflector surfaces50and51that are disposed to either side of the bases48,49. The reflector surfaces50,51are of a form that substantially corresponds to an isosceles triangle. The short side of this triangular form adjoins the respective base48,49and extends outwards away from the holding plane7at an angle. The long side of this triangular form extends outwards at an angle from the intersection point with the short side in the direction of the holding plane7. In this way the triangular reflector surfaces50,51are open in the direction of the holding plane7. The intersection points of the short sides with the long sides of the reflector surfaces50,51are further away from the holding plane7than the bases48,49extending parallel to the holding plane7. The bases48,49are therefore disposed closer to the holding plane7than a part of the reflectors29,30.

In one preferred variation of this embodiment provision is made such that the inner reflector surfaces51and50of the two reflectors29and30which face towards one another extend more steeply, i.e. enclose a smaller angle in relation to the perpendicular, onto the storage phosphor plate3than the outer reflector surfaces50and51facing away from one another. In this way particularly good “color separation” and so a particularly high level of erasing efficiency is achieved.