Motion Blurring

Since the collimator makes the radiation in the form of fan beam, the detector detects line by line the fan-beam radiograph. Compared to exposure time of film screen or FPD or CCD being 0.01 - 0.1 sec. the scan speed per line of our DR system is about 0.0035 sec.. Considering maximum motion speed is about 7 cm/sec., motion distortion cannot be seen because the relative speed between adjacent muscle or organs is relatively low. That is why instantaneous scanning X-ray exposure (scanning motion over the body) greatly reduces motion artifacts, so complete patient immobilization is not critical, which means the patient does not need to be completely still while scanning. Although it seemed that our scanning DR had a higher probability of producing a motion artifact, a previous study conducted by Samsung Medical Center demonstrated that motion in a brief period degraded only a small segment of slot scanning image, while it affects the entire portion of CR image. Continuous motion throughout the image acquisition period caused an artifact that was less apparent with our scanning DR method than the CR method. Actually, none of the scanning DR images had any significant motion artifacts leading to a difficulty in reaching the correct diagnosis.