| 摘要 |
<p>An x-ray image detector (36) monitors the intensity of incident x-rays to detect an end of radiation from an x-ray source (13) when the x-ray intensity decreases to a threshold level (Vth, Vth1) or less. The x-ray intensity gets down to zero with a variable time lag from the start of decreasing, called radiation wave tail. Depending on the gradient of declivity in time curve of the decreasing x-ray intensity, calculated at the time when the end of radiation is detected, the x-ray image detector (36) decides a delay time (Td) from the end-of-radiation detection time (T1) to a reading start time (T2) to start reading signal charges from the image detector. Thus, the reading start time (T2) may be adjusted to the point when the x-ray intensity gets down to zero, which will improve S/N ratio and prevent shading artifacts.</p> |
