Imaging plate

#The invention relates to an imaging plate for use in computed radiography.

#An imaging plate (IP) used in computed radiography comprises a plate having its active side provided with crystals activated (excited) in response to X-radiation. Excitation brings about development of a latent image on the imaging plate. The state of excitation is discharged by means of a laser beam, the imaging plate releasing energy as photons. The photons are passed by way of a photomultiplier to an AD converter, in which light is converted to digital electric signals to be reconstructed on a computer screen for an image. After reading, the image data left on an imaging plate is deleted by means of powerful light for reusing the deleted imaging plate without noise caused by prior radiography operations. A computed radiography system comprises imaging plates, a reading apparatus for the imaging plates, and a workstation with its display unit. U.S. Pat. No. 6,528,813 discloses an imaging-plate employing system, wherein the imaging plate is held in a cassette case during radiography and its passage to the reading apparatus. An imaging plate has been described in publications U.S. Pat. No. 4,236,078 and U.S. Pat. No. 4,239,968, among others.

#An imaging plate used in intraoral radiography is normally kept in a light and moisture resistant protective sleeve and placed in the mouth of a radiographed person for the duration of radiography. This is followed by removing the imaging plate from the protective sleeve and passing it to an image reading apparatus, which produces a digital image displayable e.g. on a computer screen. While in the mouth, the imaging plate runs a risk of becoming scratched or damaged on its active side, caused for example by a dental crown as a result of e.g. accidental biting. Scratches can be difficult to detect visually, yet are visible in a digital image and may interfere with diagnosis. A considerable number of imaging plates can be in service in one place, the search for a defective plate being highly tedious as scratches are not readily visible.

#The invention will now be described in more detail with reference to the accompanying drawings, in which:

#FIG. 1 shows in a schematic perspective view one prior known imaging plate reading apparatus,

#FIG. 2 shows one exemplary embodiment for an imaging plate of the invention in a view from the front, and

#Illustrated in FIG. 1 is an exemplary prior art reading apparatus 1, which houses an imaging plate reading unit and an erasing unit for clearing the imaging plate of residual radiation after reading the image. The reading apparatus 1 is provided with a gate 4, behind which is an imaging plate input slot 7. An imaging plate 2 to be passed into the reading apparatus 1 is placed against brackets 5, 6 emerging out of the slot 7 as the door 4 is opened. The brackets 5, 6 are then passed along with the imaging plate into the reading apparatus and the door 4 closes. The brackets 5, 6 are preferably provided with magnet elements fastening to the edge of an imaging plate.

#All reading apparatuses use the same basic technology, but move the plate around a little differently to scan. One system mounts the plates on a spinning drum and a laser is scanned across the drum. Another system uses rollers to move plates past a scanner laser port.

#FIG. 2 depicts one imaging plate 10 of the invention, which is provided with an imaging plate identification 11 on an active side 12 of the imaging plate. The identification is designed to be visible in each X-ray image radiographed by using the imaging plate in image examination conducted on a display screen. The IP identification is preferably made “concealed”, i.e. in a sufficiently small size not to interfere with diagnosis but capable of being visualised by enlarging an image presently under examination. The IP identification can be e.g. an alphanumerical character, a device character, or e.g. a bar code. FIG. 3 illustrates an imaging plate identification character 13 in a larger size on a reverse side 14 of the imaging plate, whereby it is readily detectable visually in the process of searching a possibly defective imaging plate from among a plurality of imaging plates.