Appeal No. 2003-2103 Page 2
Application No. 09/826,256
image. As explained on page 1 of appellants’ specification, incident x-rays release
electric charge carriers in the x-ray image sensor matrix and these electric charges are
detected. Some of the charge carriers can be trapped in a trap-state, be retained in
such a trap-state, and escape from the trap-state at a later time such that they are
detected as electric charges with a delay. If the initial image signal were applied to a
monitor without correction, not only the image information from the instantaneous image
but also image information of a previously picked-up image would be reproduced. As a
result, after-images would be displayed together with the instantaneous image.
The correction unit of appellants’ invention includes a memory for storing
correction values and an arithmetic unit for computing signal levels of the corrected
image signals from signal levels of the initial image and at least some of the correction
values. The correction values are obtained from a separate calibration of the x-ray
examination apparatus. This calibration is carried out by applying a pre-selected
number of x-ray pulses with a pre-selected pulse-width, pulse-rate and x-ray dose per
pulse. Subsequent to the calibration x-ray exposure, the charge carriers in respective
sensor elements of the x-ray sensor matrix are detected. The period of time lapsed
between the calibration exposure and the generation of the calibration signal image
signal is recorded or controlled. The calibration image signal represents the electric
charges emitted during read-out after said period of time since the predetermined
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