Method of processing a radiation image storage medium

0001The invention relates to a method for processing an image carrier for recording x-ray images according to the preamble of claim 1.

0002Corresponding image carriers are used, in particular for medical purposes, in the field of computer radiography (CR). Here, X-ray recordings are recorded in a storage phosphor layer by storing the X-ray radiation passing through an object, for example a patient, as a latent image in the storage phosphor layer. To read out the stored X-ray information, the storage phosphor layer is irradiated with stimulation light, whereby it is stimulated to emit emission light, which is detected by an optical detector and converted into electrical signals. The electrical signals can be processed as required and displayed on a monitor or on an appropriate output device, such as. B. a printer. After an erasing process in which any remaining x-ray information is completely eliminated from the storage phosphor layer, the storage phosphor layer is available for further x-ray exposures.

0003Since storage phosphor layers generally have different sensitivities for X-rays, the sensitivity of the respective storage phosphor layer for X-rays must be taken into account when processing the image signals obtained when reading the image carrier. The corresponding data, which represent a measure of the sensitivity of the storage phosphor layer of an image carrier to X-ray radiation, are usually supplied with the image carrier ex works on a separate data carrier. If the individual data carriers, which generally belong to different image carriers, are mixed up, the image signals obtained from a storage phosphor layer of an image carrier may be incorrectly corrected with the corresponding data from another image carrier. This leads to an intolerable falsification of the x-ray information read out.

0004<patcit id="pcit0001" dnum="EP1391780A1"><text>EP 1 391 780 A1</text></patcit> discloses an image carrier with a storage element in which information for correcting the sensitivity of the storage phosphor plate is stored. In<patcit id="pcit0002" dnum="US4320296A"><text>US 4,320,296</text></patcit> the storage of image processing data is described as a measure of the x-ray dose stored in the phosphor plate. Out<patcit id="pcit0003" dnum="EP1031854A1"><text>EP 1 031 854 A1</text></patcit> a method for image data correction is known. <patcit id="pcit0004" dnum="EP1251683A1"><text>EP 1 251 683 A1</text></patcit> discloses a network for transferring image data obtained by reading out storage phosphor panels. Out<patcit id="pcit0005" dnum="EP0727696A1"><text>EP 0 727 696 A1</text></patcit> the use of radio elements that can be read out by radio frequency radiation, so-called RF tags, is known for X-ray cassettes. <patcit id="pcit0006" dnum="WO0242794A2"><text>WO 02/42794 A2</text></patcit> discloses an integrated radiation detector with a reference to a calibration data set, on the basis of which sensitivity fluctuations of the detector can be corrected.

0005In the methods and systems known from the prior art, the large amount of correction data requires a relatively long time before these are available for the image data correction. In addition, transmission errors can occur.

0006It is an object of the present invention to provide a method for processing the image carrier, in which different sensitivities of the image carrier for X-ray radiation are made available in a time-saving manner and with increased reliability.

0007This object is achieved by the method according to claim 1.

0008The method according to the invention for processing the image carrier is characterized in that the image carrier comprises an electronic memory for storing calibration data of the image carrier, which represent a measure of the sensitivity of the image carrier to X-ray radiation and when processing image signals which are carried out when the X-ray information is read out the image carrier can be obtained, can be used and after a first readout of the calibration data from the electronic memory of the image carrier, the calibration data are stored in a memory, in particular in a central memory or in a memory of a readout device.

0009When the same image carrier is processed again, the calibration data of this image carrier stored after the first reading out are then read from the memory, in particular the memory of the reading device or the central memory. As a result, the calibration data are available for image signal processing in a shorter time than when the two-dimensional data record is read out again from the electronic memory of the image carrier. Any transmission errors when reading the data record from the electronic memory can also be avoided in this way.

0010The calibration data of the image carrier is preferably read out for the first time from the electronic memory of the image carrier in the readout device.

0011The image carrier has an electronic memory for storing calibration data of the image carrier, the calibration data representing a measure of the sensitivity of the image carrier to X-ray radiation and can be used in the processing of image signals which are obtained when the X-ray information is read from the image carrier.

0012By storing the calibration data in the electronic memory located on the image carrier, an additional transmission of the calibration data via an additional data carrier can be omitted. This also prevents confusion of individual data carriers and thus increases the reliability when considering different sensitivities of the image carriers.

0013The electronic memory is preferably designed as an integrated electronic circuit with a non-volatile memory, for example as a ROM, PROM, EPROM or EEPROM.

0014The calibration data of the image carrier preferably represent a measure of a locally variable sensitivity of the image carrier for X-ray radiation via a storage phosphor layer of the image carrier. This not only takes into account different sensitivities of individual image carriers, but also individually occurring variations in sensitivity over the entire area of ​​the storage phosphor. Layer of a single image carrier. This increases the accuracy of the calibration.

0015The calibration data, which represent a measure of the locally variable sensitivity of the image carrier to X-ray radiation, are preferably stored in a two-dimensional data field in the electronic memory of the image carrier. This results in a clear correlation of individual areas of the storage phosphor layer with their respective sensitivity.

0016In a further embodiment it is provided that the calibration data of the image carrier reflect the locally variable sensitivity of the image carrier in individual areas of the image carrier, the individual areas corresponding to the individual image points (pixels) which are obtained when the x-ray information stored in the image carrier is read out. This enables pixel-precise calibration, which takes into account locally different sensitivities with very high accuracy.

0017In an alternative embodiment, however, it can also be provided that the calibration data of the image carrier reflect the locally variable sensitivity of the image carrier in individual areas of the image carrier, the individual areas being larger than the individual image points (pixels) that are stored in the image carrier when reading them out X-ray information can be obtained. In this way, the storage space requirement for the calibration data in the electronic memory can be greatly reduced, while locally different sensitivities are nevertheless taken into account with high accuracy.

0018In a further embodiment of the invention, the calibration data of the image carrier are stored in a calibration data group in the electronic memory of the image carrier. In this way, a clear division of the memory content is achieved and easier access to the calibration data of the calibration data group is made possible.

0019In a further advantageous embodiment, the image carrier comprises an image plate for storing the X-ray information, the electronic memory preferably being attached to the image plate. This ensures a reliable assignment of the calibration data stored in the electronic memory to the associated image plate.

0020In one embodiment of this variant, it is provided that the image plate comprises a carrier layer with a storage phosphor layer located on the front of the carrier layer and the electronic memory in an edge region of the carrier layer, in particular outside the storage phosphor layer, and / or on the opposite side of the front Back of the carrier layer is attached. In this way, an impairment of the storage properties of the storage phosphor layer by the electronic storage is avoided.

0021As a rule, the image carrier comprises, in addition to the image plate, a cassette which can record the image plate while shielding it from ambient light. If the electronic memory is designed for contactless data transmission, its memory content can also be read out from the outside of the cassette through the cassette wall using a corresponding RF reader.

0022In an alternative embodiment of the invention, the electronic memory is attached to the cassette. In this case, the cassette does not have to be opened and the image plate does not have to be removed if the electronic memory can only be read out by galvanic contacting.

0023The calibration data are advantageously stored in compressed form in the electronic memory of the image carrier. This can greatly reduce the amount of storage space required. JPEG is a suitable data compression method, for example.

0024A corresponding system for processing an image carrier for storing X-ray information consists of at least one image carrier and at least one device for processing the image carrier and / or for further processing and / or reproduction of the X-ray information stored in the image carrier and is characterized in that the image carrier has an electronic memory for storing calibration data of the image carrier, which represent a measure of the sensitivity of the image carrier to X-ray radiation and can be used when processing image signals which are obtained when the X-ray information is read from the image carrier.

0025In this case, a device is designed as a read-out device which can read out the x-ray information stored in the image carrier and thereby generate corresponding image signals and can process the generated image signals using the calibration data of the image carrier stored in the electronic memory. The readout device is preferably equipped with a corresponding reading device with which the calibration data of the image carrier stored in the electronic memory of the image carrier can be read.

0026Further features and advantages of the invention result from the following description of preferred embodiments and application examples, reference being made to the attached figures.

0027Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>a system for processing an image carrier for X-ray information;</dd><dt>Fig. 2</dt><dd>a first example of a structure of the data stored in the integrated circuit of the image carrier;</dd><dt>Fig. 3</dt><dd>is a schematic representation of a first variant of the data flow between individual components of the in <figref idref="f0001">Fig. 1</figref> represented system;</dd><dt>Fig. 4</dt><dd>is a schematic representation of a second variant of the data flow between individual components of the in <figref idref="f0001">Fig. 1</figref> represented system; and</dd><dt>Fig. 5</dt><dd>a second example of a structure of the data stored in the integrated circuit of the image carrier.</dd></dl>

0028<figref idref="f0001">Fig. 1</figref> shows a system for processing an image carrier for X-ray information. The system comprises an identification station 10, which is also referred to below as an ID station, a read-out device 20, a reproduction device 30 and a central memory 40.

0029The image carrier for X-ray information consists of a cassette 2 with an image plate 1 located therein. The image plate 1 comprises a carrier layer with a storage phosphor layer 5 applied thereon. The storage phosphor layer 5 preferably has a storage phosphor based on BaFBr: Eu or CsBr: Eu on.

0030The optical disc 1 is provided with an integrated circuit 3 which comprises a read-write memory in which data can be written and from which data can be read. In order not to impair the storage function of the storage phosphor layer 5, the integrated circuit 3 is preferably arranged on the back or — as in the example shown — in the edge region of the image plate 1.

0031Alternatively or additionally, the integrated circuit 3 can be attached to the cassette 2. The following statements, which relate to an integrated circuit 3 located on the image plate 1, also apply accordingly to this alternative.

0032After an X-ray exposure, the image plate 1 located in the cassette 2, in the storage phosphor layer 5 of which X-ray information is stored, is brought to the ID station 10 in order to read or write data from and / or into the integrated circuit 3. The data transmission between the integrated circuit 3 and the ID station 10 is preferably contactless. As a result, an exact positioning of the image plate 1 and the circuit 3 relative to the ID station 10, as would be required in the case of contact-based data transmission, can be dispensed with. The contactless data transmission is preferably carried out by means of radio frequency waves (RF waves). For this purpose, the ID station 10 has a corresponding first read / write device 11 with an RF transmitter and an RF receiver.

0033The integrated circuit 3 is preferably attached, for example glued, to the image plate 1 in the form of a so-called RF label, which is also referred to as an RF tag. In addition to the integrated circuit 3, such an RF tag comprises an antenna designed as a transponder coil. Instead of an RF tag, the integrated circuit 3 can also be attached to the image plate 1 in the form of a chip card, in which an RF tag is inserted into a card-shaped plastic body. The chip card is preferably releasably attached to the image plate 1, for example by means of a simple plug connection in the edge region of the image plate 1. A locking mechanism can be provided, for example a snap mechanism, in which the chip card is locked by snapping it in place. This attachment of the chip card to the image plate 1 is simple and secure on the one hand and on the other hand simplifies the replacement of the chip card with another, for example in the event of a defect in the integrated circuit 3.

0034The image plate 1 is provided with a mark 4 which can be read by the naked eye and which represents at least part of the data stored in the memory of the integrated circuit 3, in particular data specific to the image plate 1, and is preferably designed as an alphanumeric character string. As a result, in the event of a defect in the integrated circuit 3, in which the data stored therein can generally no longer be read out, the data contained in the marking 4 are still accessible. In this case, the defective integrated circuit 3 can be exchanged for a new one, in which the data contained in the marker 4 are then written. For this purpose, the data of the marker 4 are read by an operator, entered at the ID station 10 and finally written into the new integrated circuit. With the help of the marker 4, it is thus ensured in a simple manner that the part of the data stored in the integrated circuit 3 and contained in the marker 3 is not lost even if the circuit 3 is defective.

0035Alternatively or additionally, a marking 4 designed in this way can also be attached to the cassette 2. The procedure in the event of a defect in the integrated circuit is carried out in an analogous manner.

0036The ID station 10 comprises one or more input devices for the input of data which are specific or required, for example, for a patient to be examined, the reading of the image plate 1 or the further processing of image data read from the image plate 1. In the example shown, the input devices comprise a keyboard 13 with a display unit 12, such as. B. a monitor and a card reader 15 for a card 14 on which data to be entered are located. In particular, the card 14 is a chip card, for example a health insurance card, on which patient-specific data, such as the name, address, date of birth and insurance number of a patient, are stored. The card reader 15 reads this data from the card 14 and transfers it to an intermediate memory 16 of the ID station 10. The data entered via the keyboard 13 are also transferred to the buffer memory 16. The display unit 12 can preferably also be a so-called touchscreen, in which the functions and / or data displayed can be selected by touching the corresponding areas of the display.

0037The input data are transferred from the buffer memory 16 to the first read / write device 11 and written into the memory of the integrated circuit 3 on the optical disk 1.

0038Instead of the input data itself, a reference code assigned to this data can be written into the memory of the integrated circuit 3, while the input data are stored together with the reference code assigned to them in the buffer memory 16 and / or in the central memory 40. This procedure is discussed in more detail below.

0039The cassette 2 with the image plate 1 located therein is then brought to the read-out device 20, where the cassette 2 is automatically opened, the image plate 1 is removed and drawn into the interior of the read-out device 20. In the position shown here, the optical disc 1 has already been completely pulled out of the cassette and locked in the interior of the reading device 20. In this position, it is read out by a scanner 21, which is moved with a suitable transport mechanism 22 in the transport direction T over the image plate 1.

0040The scanner 21 is preferably designed as a so-called line scanner, which has a line-shaped stimulation light source, preferably with laser diodes arranged in a row, and a line-shaped detector, preferably a linear CCD array. During the movement of the scanner 21 over the image plate 1, the latter is irradiated line by line with the light from the stimulation light source, emission light being excited in the storage phosphor layer 5, the intensity of which corresponds to the x-ray information stored in the storage phosphor layer 5. The emission light is detected with the line-shaped detector and converted into corresponding image signals. Due to the continuous movement of the scanner 21 in the transport direction T over the image plate 1, the storage phosphor layer 5 is read out successively line by line, a two-dimensional image of the stored X-ray information being obtained.

0041Alternatively, the scanner 21 can also be designed as a so-called flying spot scanner, in which a single laser beam is directed onto the storage phosphor layer 5 by a rotating polygon mirror, as a result of which it is scanned point by point along individual lines.

0042After the image plate 1 has been completely read out, it is automatically conveyed back into the cassette 2. In doing so, it passes through an extinguishing device 23, at which any remaining x-ray information in the image plate 1 is deleted by irradiating the storage phosphor layer 5 with extinguishing radiation. For this purpose, the extinguishing device 23 comprises a radiation source with a broader spectrum compared to the stimulation light source and a suitable reflector for reflecting extinguishing radiation onto the storage phosphor layer 5 of the image plate 1.

0043The readout device 20 comprises a second read / write device 24 with which data can be read or written from or into the integrated circuit 3. Like the first read / write device 11 of the ID station 10, the second read / write device 24 is also preferably designed for contactless data transmission, in particular by means of RF waves. The data read from the memory of the integrated circuit 3 with the second read / write device 24 are used in particular to control the reading of the image plate 1 with the scanner 21 and / or to control the deletion of the image plate 1 with the erase device 23. In addition, data can be written into the integrated circuit 3 with the second read / write device 24, in order to preferably update data on the processing status of the image plate 1 - for example whether the image plate 1 has already been read out or deleted.

0044When the image plate 1 is read line by line with the scanner 21, image data are generated which represent the x-ray information stored in the image plate 1. This image data is transmitted to the central memory 40 via a first data bus 25, in particular a serial data bus, such as a so-called fire wire, and is stored there.

0045The image data stored in the central memory 40 can then be further processed and / or reproduced in the reproduction device 30. For this purpose, the playback device 30 comprises a monitor 31 which can be controlled by means of a keyboard 32. Alternatively or additionally, a hard copy device 33, for example a laser printer, can also be provided for outputting the image data.

0046The central memory 40 can optionally be connected to a network 50, in particular to a local area network (LAN). This enables other systems, in particular other ID stations and / or playback devices, to access the data or image data stored in the central memory 40.

0047The central memory 40 can be designed as a separate central unit, which can be integrated, for example, in a central file server. Alternatively, the central memory 40 can also be an integral part of the ID station 10, the reading device 20 or the playback device 30.

0048<figref idref="f0002">Fig. 2</figref> shows a first example of a structure of the data stored in the memory M of the integrated circuit 3 of the image carrier. Using this structure, the data transmission within the in<figref idref="f0001">Fig. 1</figref> described system explained in more detail. It should be noted that the representation selected here only shows the structure of the data in a highly schematic manner and is not restricted to a specific spatial arrangement or a specific sequence of the data in the memory M of the integrated circuit 3.

0049The data stored in the memory M are combined in different data groups IPI, IPS, IPC, IPP, CAL and IDP and are each stored there as an ASCII string. A version number VN and a checksum CS are assigned to each data group.

0050The version number VN at the beginning of each data group indicates the data structure in which the data of a data group are stored. This opens up the possibility of providing different data structures in one and the same data group. This is always necessary when other or additional data are to be stored in the memory M, for example with a new type of image plate or a new type of further processing of the image data. On the basis of the version number VN of a data group, the individual components of the system, for example the ID station 10, the read-out device 20 or the playback device 30, can recognize which data are contained in the respective data group and in which data length, sequence etc. these data are present .

0051The checksum CS at the end of each data group is derived from the individual data of this data group. The respective checksum CS can be used to determine whether the data in this data group has been stored or read without errors. The rest of the division of the sum Σ of the numerical values ​​of all the bytes contained in this data group by 256, ie, serves as the checksum CS<maths id="math0001" num=""><math display="block"><mi>CS</mi><mo>=</mo><mi mathvariant="normal">Σ modulo</mi><mspace width="1em" /><mn>256.</mn></math><img file="EP1544674B1_D0001.tif" /></maths>

0052The structure and function of the individual data groups IPI, IPS, IPC, IPP, CAL and IDP are explained in more detail below.

0053An image carrier data group IPI contains specific data of the image plate 1 and / or the cassette 2. This data is stored in the memory M during the manufacture of the image plate 1 or the cassette 2 and remains when the image plate 1 or the cassette 2 is processed the ID station 10 and / or in the readout device 20 unchanged, ie at the ID station 10 or in the readout device 20, the data stored in the image carrier data group IPI are read exclusively. In addition to the version number VN and the checksum CS, the image carrier data group IPI includes the following data:<ul id="ul0001" list-style="dash" compact="compact"><li>Initialization date: corresponds to the date on which the data of the image carrier data group IPI were written into the memory M of the image plate 1;</li><li>Image plate serial number: serves to uniquely identify the image plate 1 and is preferably composed of a code identifying the respective product batch of the image plate 1 and a serial number;</li><li>Image plate size;</li><li>Size of an area to be read on the optical disc 1;</li><li>Image plate type: eg image plate based on powdered or needle-shaped storage phosphors, such as so-called powder IP or needle IP;</li><li>Optical disc sensitivity;</li><li>Optical disk extinguishing property: for example as a measure of the duration and / or intensity of the light emitted by an extinguishing device 23.</li></ul>

0054Preferably, the content of the image carrier data group IPI is additionally shown as a visually readable marker 4 (see <figref idref="f0001">Fig. 1</figref>) applied to the optical disc 1 and / or the cassette 2. This has the advantage that the data of the image carrier data group IPI specific for the image plate 1 or cassette 2 and required for its processing cannot be lost even if the integrated circuit 3 is defective and can no longer be read out. In such a case, the defective integrated circuit 3 is simply exchanged for a new integrated circuit, which is then written with the data taken from the marker 4. Such a marking 4 can be, for example, as follows:<maths id="math0002" num=""><math display="block"><mn>301</mn><mo>-</mo><mn>6</mn><mo>⁢</mo><mi>KBQMF</mi><mo>⁢</mo><mn>0001</mn><mo>-</mo><mn>20030702</mn><mo>-</mo><mn>1</mn><mo>-</mo><mn>1</mn><mo>-</mo><mn>0</mn><mo>-</mo><mn>1000</mn><mo>-</mo><mn>1000</mn><mo>-</mo><mn>123</mn></math><img file="EP1544674B1_D0002.tif" /></maths>

0055The first three (301) and the last three (123) characters contain the version number VN or the checksum CS. The version number VN is followed by the image plate serial number (6KBQMF0001), the initialization date (20030702), values ​​for the image plate size (1), the size (1) of the area of ​​the image plate to be read and the image plate type (0), the image plate sensitivity (1000 ) and finally the image plate erase property (1000).

0056The data taken from the marker 4 can be written in a simple manner into the memory of the new integrated circuit at the ID station 10 without a new initialization being required by the manufacturer of the optical disk 1 or cassette 2. In the simplest case, the data of the marker 4 are read by an operator, entered via the keyboard 13 of the ID station 10 and then written into the memory of the new integrated circuit.

0057The above-described mark 4, which can be read visually, ie with the human eye, represents a particularly simple possibility for additionally securing data stored in the integrated circuit 3. Of course, instead of a visually readable mark, a machine-readable mark (not shown) can alternatively or additionally be provided be, for example in the form of a barcode or magnetic strip. To enter the data contained in the machine-readable marking, a corresponding barcode or magnetic stripe reader is then required, which forwards the machine-read data to the ID station 10, where it can then be written into the new integrated circuit.

0058The data of a status data group IPS relate to the respective processing status of the optical disc 1 or the cassette 2 and are changed both in the ID station 10 and in the readout device 20. In addition to the version number VN and the checksum CS, this data group includes the following data:<ul id="ul0002" list-style="dash" compact="compact"><li>Image plate status: for example whether the image plate 1 has already been initialized (ie data of the image carrier data group IPI are stored in the memory M) and / or an X-ray image has already been taken, deleted or still to be deleted;</li><li>Image plate cycles: total number of x-ray recordings with this image plate 1. This total number is increased by the value 1 after each read-out or erase operation in the read-out device 20;</li><li>Reading under bending: number of image plate cycles in which the image plate 1 is curved during the reading process. This number is a measure of the degree of wear and / or damage to an optical disc 1. This entry can be omitted, for example, in systems in which the optical disc rests on a solid, flat surface during reading and is consequently not bent.</li></ul>

0059A control data group IPC comprises all data specific to an X-ray exposure that are required for reading the image plate 1 in the reading device 20. The readout device 20 has only read access to the data stored in the control data group IPC. In addition to the version number VN and the checksum CS, the control data group IPC includes the following data:<ul id="ul0003" list-style="dash" compact="compact"><li>Scanner sensitivity: indicates the sensitivity to be set in the scanner 21 when reading the image plate 1 and is dependent on the x-ray dose in areas of the image plate 1 which contain diagnostic information;</li><li>X-ray dose: corresponds to the maximum X-ray dose during an X-ray exposure and represents a measure of the intensity of the erasing device 23 to be set when erasing the image plate 1;</li><li>Operating mode: eg omitting or reading out X-ray information from certain edge areas of the image plate 1.</li></ul>

0060Data that are required for further processing of image data obtained from the X-ray information of the image plate 1 are stored in a processing data group IPP. This data is accessed exclusively by the reproduction device 30, which comprises a corresponding image processor for further processing of the image data. The reading process in the reading device 20 is not influenced by this data.

0061The data of the processing data group IPP are preferably read with the second read / write device 24 in the read-out device 20 and stored in the central memory 40 together with the image data obtained from the image plate 1. The reproduction device 30 can then easily access both the image data to be processed and the data of the processing data group IPP required for this.

0062In a preferred embodiment, it is provided to enter the data of the processing data group IPP required for the further processing of the image data in the ID station 10 and to assign them unique reference codes (IPP-Ref) which are then stored in the memory M instead of the data for further processing to be written. The data for further processing itself are stored in the central memory 40 together with the reference codes (IPP-Ref). The playback device 30, which requires the data stored in the central memory 40 for further processing, can then access the data stored in the central memory 40 for further processing on the basis of the reference codes (IPP-Ref) transmitted with the image data from the reading device 20. In addition to the version number VN and the checksum CS, the processing data group IPP in this case includes the following data:<ul id="ul0004" list-style="dash" compact="compact"><li>Reference code for the type of further processing to be carried out;</li><li>Reference code for admission and patient data;</li><li>Clear identification of the central memory to which the reference codes refer, such as the name of the central memory in a network.</li></ul>

0063A calibration data group CAL comprises calibration data of the image plate 1. The calibration data are preferably in the form of a two-dimensional data field which reflects the different local sensitivity of the image plate 1 to X-rays. The data of the calibration data group CAL are preferably together with the data of the image carrier data group IPI during the production and initialization of the image plate 1 or the cassette 2 stored in the memory M of the integrated circuit 3 and not changed during the processing of the optical disc 1 or the cassette 2. In addition to the version number VN and the checksum CS, the calibration data group CAL includes the following data:<ul id="ul0005" list-style="dash" compact="compact"><li>Number of columns of the two-dimensional data field of the calibration data;</li><li>Number of lines of the two-dimensional data field of the calibration data;</li><li>two-dimensional data field of the calibration data.</li></ul>

0064The calibration data of the image plate 1 are used in the reading device 20 for a preliminary evaluation of the image signals obtained when the image plate 1 is read out by means of a scanner 21, in order to take into account locally different sensitivities of the image plate 1 for X-radiation. For this purpose, the calibration data are read from the integrated circuit 3 in the readout device 20 and fed to the preprocessing of the image signals.

0065Calibration data that have been read out are preferably stored in a memory (not shown) of the readout device 20 or transmitted to the central memory 40 via the first data bus 25 and stored there. If the same image plate 1 with another X-ray image is then subjected to a readout process in the same readout device 20, this readout device 20 can be directly loaded onto the memory of the readout device 20 or access the central memory 40 and call up the calibration data of the image plate 1 required for the preprocessing of the image signals. As a result, the calibration data are available for preprocessing in a shorter time than when the two-dimensional data record is read out again from the integrated circuit 3. This also avoids any transmission errors when reading the data record from the integrated circuit.

0066Alternatively, the calibration data can already be read out of the integrated circuit 3 at the ID station 10, transmitted to the central memory 40 via a second data bus 17 and stored there. There is then no need to read out and transfer the calibration data to the central memory 40 during the first readout process in the readout device 20. The second data bus 17 is preferably also in the form of a serial data bus, for example an RS-232 data bus.

0067In principle, it is possible to read the two-dimensional data field of the calibration data of the image plate 1 anew from the integrated circuit 3 each time the reading process in the reading device 20 takes place. In this case, a permanent connection between the reading device 20 and the central memory 40 can optionally be dispensed with entirely, or at least the data flow between the individual components of the system, in particular between the reading device 20 and the central memory 40, can be kept particularly low.

0068In addition to the calibration data of the image plate 1, calibration data of the scanner 21 are also stored in the central memory 40 or in the memory of the reading device 20, which reflect local differences in the sensitivity of the scanner 21 and are preferably used together with the calibration data of the image plate 1 for preprocessing the image signals become. From the preprocessing of the image signals, image data of the x-ray image stored in the image plate 1 are finally obtained, from which the influence of locally different sensitivities of the image plate 1 and the scanner 21 has been eliminated.

0069The two-dimensional data field of the calibration data of the image plate 1 typically has between approximately 30 and 40 columns and between approximately 40 and 50 rows, the length of the respective data being two bytes in each case. The memory size to be reserved for such a two-dimensional data field is accordingly 2 x 35 x 43 = 3010 bytes for a data field which preferably has 35 columns and 43 rows.

0070In the example described, the calibration data represent the sensitivity of individual regions of the storage phosphor layer 5 which are larger than the individual image points (pixels) obtained when the image plate 1 is read line by line. In this way, the storage space requirement for the calibration data in the integrated circuit 3 can be greatly reduced, with locally different sensitivities being taken into account with high accuracy.

0071If there is sufficient storage space in the integrated circuit 3, the calibration data can also reproduce the sensitivity of the image plate 1 in individual areas of the image plate which correspond to the individual pixels. This enables pixel-precise calibration that takes locally different sensitivities into account with even greater accuracy.

0072In order to take up as little memory space as possible in the memory M of the integrated circuit 3, the calibration data of the optical disk 1 are advantageously subjected to a compression process before they are stored in the integrated circuit 3.

0073Data which are specific for a patient to be examined are stored in a patient data group IDP. In addition to the version number VN and the checksum CS, the patient data group IDP includes the following data, for example:<ul id="ul0006" list-style="dash" compact="compact"><li>Name of the patient;</li><li>Date of birth of the patient;</li><li>Gender of the patient.</li></ul>

0074Instead of or in addition to the aforementioned patient-specific data of the patient data group IDP, a reference code IDP-Ref is written into the memory M, which represents a reference to the data of the patient data group IDP, which are stored in the central memory 40. The reference code IDP-Ref, which is also referred to as the patient identification code and enables unambiguous identification of the patient, is written with the first read / write device 11 of the ID station 10 into the memory M of the integrated circuit 3 and together with the Data of the patient data group IDP are stored in the intermediate memory 16 of the ID station 10 and / or in the central memory 40.

0075The patient-specific data stored in the intermediate memory 16 or central memory 40 can then be accessed using the patient identification code IDP-Ref. For this purpose, the patient identification code IDP-Ref is either in the ID station 10 or read in the reading device 20 from the integrated circuit 3 and transferred to the playback device 30 or transferred together with the image data read out from the optical disc 1 to the playback device 30, which then uses the patient identification code IDP-Ref to the corresponding patient-specific data in the buffer memory 16 or central memory 40 can access.

0076In principle, the patient data group IDP can also be omitted if reference codes for patient data are already provided in the processing data group IPP, as already described above, which, among other things, refer to the corresponding patient data, such as name and / or date of birth and / or gender of the patient Patients, refer to central store 40.

0077<figref idref="f0003">Fig. 3</figref> shows a schematic representation of a first variant of the data flow between the individual components of the in <figref idref="f0001">Fig. 1</figref> shown system. The data flow is explained in more detail below using a complete radiography process.

0078Immediately after an x-ray of a patient, the cassette 2 with the image plate 1 located therein is brought to the ID station 10. The following steps are carried out at the ID station 10:<ol id="ol0001" compact="compact" ol-style=""><li>a) Reading data from the status data group IPS on the processing status of the image plate 1 from the memory M of the integrated circuit 3. Check whether the processing status is set to "image plate initialized" or "image plate deleted". If the image plate has not been initialized or has not been deleted, the operator must choose between two alternatives, namely overwriting the data or aborting the processing.</li><li>b) Entering patient-specific data of the patient data group IDP using the keyboard 13 and / or display unit 12 and / or card 14.</li><li>c) Input of the data of the control data group IPC required for reading the image plate 1 in the reading device 20 using the keyboard 13 and / or display unit 12.</li><li>d) Input of data of the processing data group IPP required for the further processing of image data in the reproduction device 30 by means of the keyboard 13 and / or display unit 12.</li><li>e) Writing the input data of the control, processing and patient data group IPC, IPP or IDP into the memory M of the integrated circuit 3 of the optical disk 1 or cassette 2.</li><li>f) Writing data of the status data group IPS for the current processing status into the memory M: processing status is set to "X-ray image taken".</li></ol>

0079Then the cassette 2 with the image plate 1 located therein is brought to the reading device 20. There, the image plate 1 is read out line by line using the scanner 21, image signals being generated which correspond to the X-ray information stored in the image plate 1. The image signals are subjected to a preprocessing in which image data IMD are obtained, which can be passed on to the reproduction device 30. The following steps are carried out in detail in the reading device 20:<ol id="ol0002" compact="compact" ol-style=""><li>a) Reading data from the image carrier, status, control, processing and patient data group IPI, IPS, IPC, IPP or IDP from the memory M.</li><li>b) Reading data from the calibration data group CAL, ie calibration data from the image plate 1, from the memory M. Or:<ul id="ul0007" list-style="none" compact="compact"><li>Reading of data from the calibration data group CAL already stored in a memory (not shown) of the reading device 20 during a previous reading process of this optical disc 1.</li></ul></li><li>c) Checking the read data of the status data group IPS whether the processing status of the image plate 1 is set to "X-ray image taken". Otherwise the further processing is canceled.</li><li>d) Reading calibration data (CALS) of the scanner 21 stored in a memory of the reading device 20.</li><li>e) Reading out the X-ray information stored in the image plate 1 line by line using the scanner 21 using data from the image carrier and control data group IPI or IPC and generating corresponding image signals.</li><li>f) preprocessing of the generated image signals based on the calibration data CAL of the image plate 1 and the calibration data (CALS) of the scanner 21 to image data IMD.</li><li>g) Erasing any remaining X-ray information in the image plate 1 with the eraser 23 using data from the image carrier and control data group IPI or IPC.</li><li>h) storing the image data IMD together with the data of the processing and patient data group IPP or IDP in the central memory 40.</li><li>i) Writing data of the status data group IPS on the current processing status of the image plate 1 into the memory M: "image plate read out" or "image plate deleted".</li></ol>

0080Optionally, in step h), the data of the image carrier and / or control data group IPI or IPC can also be stored together with the image data IMD in the central memory 40.

0081The image data IMD generated when the image plate 1 is read out can then be displayed in the playback device 30 on a monitor 31 and / or output on a hardcopy device 33. The following steps are carried out:<ol id="ol0003" compact="compact" ol-style=""><li>a) Reading the image data IMD and the associated data of the processing and patient data group IPP or IDP from the central memory 40.</li><li>b) Further processing of the image data IMD based on the data of the processing data group IPP.</li><li>c) Playback - for example on the monitor 31 and / or hardcopy device 33 - of the further processed image data IMD using the data of the processing and / or patient data group IPP or IDP.</li></ol>

0082In a modification of the <figref idref="f0003">Fig. 3</figref> Data flow shown are one or more reference codes IPC-Ref, IPP-Ref or IDP-Ref in the memory M of the integrated station at the ID station 10 instead of the data of the control, processing and patient data group IPC, IPP or IDP Circuit 3 of the optical disk 1 or cassette 2 written. The reference codes IPC-Ref, IPP-Ref or IDP-Ref are together with the corresponding data of the control, processing and patient data group IPC, IPP or IDP stored in the central memory 40. The readout device 20 can then access the data of the corresponding data group IPC, IPP or IDP stored in the central memory 40 on the basis of the reference codes IPC-Ref, IPP-Ref or IDP-Ref. The reference codes IPC-Ref, IPP-Ref or IDP-Ref transmitted in this modification, possibly with the associated data of the corresponding data group IPC, IPP or IDP, are in the<figref idref="f0003">Fig. 3</figref> in parentheses (). Otherwise, the above statements apply accordingly.

0083<figref idref="f0004">Fig. 4</figref> shows a schematic representation of a second variant of the data flow between the individual components of the in <figref idref="f0001">Fig. 1</figref> shown system. In this variant of the data flow, data of the status, control, processing and patient data group IPS, IPC, IPP or IDP are entered at the ID station 10, as described in more detail above, but not in the memory M of the integrated circuit 3 located on the optical disk 1, but transferred to the central memory 40 and stored there. In this variant, only data of the image carrier and calibration data group IPI or CAL are stored in the memory M of the integrated circuit 3. Accordingly, only data from the image carrier and calibration data group IPI or CAL, which include image plate-specific data or the calibration data of the image plate 1, are read from the integrated circuit 3 in the readout device 20. In contrast, the data of the status data group IPS on the processing status of the image plate 1 and the data of the control data group IPC required for reading out the X-ray information from the image plate 1 and then deleting remaining image information are read from the central memory 40. Otherwise the explanations apply<figref idref="f0003">Fig. 3</figref> corresponding.

0084With the in the examples of <figref idref="f0003">Figures 3</figref> and <figref idref="f0004">4</figref> The image plates 1 shown are the mark 4, which represents part of the data stored in the memory M of the integrated circuit 3, in particular data of the image carrier data group IPI, on the back of the carrier layer of the image plate 1. The marking 4 is therefore shown in dashed lines.

0085<figref idref="f0002">Fig. 5</figref> shows a second example of a structure of the data stored in the integrated circuit 3 of the image carrier in the in <figref idref="f0004">Fig. 4</figref> shown variant of the data flow. As already explained, only data of the image carrier and calibration data group IPI or CAL are stored in the memory M in this variant. The above statements apply to the structure and content of the individual data groups IPI or CAL<figref idref="f0002">Fig. 2</figref> corresponding.

0086In this variant, the storage space requirement in the memory M of the integrated circuit compared to that in the <figref idref="f0002">Figures 2</figref> and <figref idref="f0003">3</figref> shown example can be reduced.

0087In the in the <figref idref="f0002">Figures 2</figref> and <figref idref="f0003">3</figref> The example shown, on the other hand, requires more storage space, but the reading device 20 can take the data required for reading or deleting directly from the memory M of the integrated circuit 3 on the image plate and does not have to access the central memory 40 for this. As a result, the readout device 20 is independent of a central memory 40.