| 摘要 |
<p>An imaging detector (18) on a medical imager (10) is provided with a proximity sensor (38A, 40A) for automatically maintaining a desired distance from the subject (24) to be imaged. The proximity sensor (38A, 40A) is formed from three infrared beams (50, 52, 54) at decreasing distances from the imaging detector (18). The imaging detector (18) is moved toward the subject until the first two beams (50, 52) are interrupted. If the third beam (54) is interrupted, the imaging detector (18) is moved back from the subject (24) until only the first beam (50) is interrupted. Faults are dtected by monitoring the order in which the beams (50, 52, 54) are interrupted, whether the beams (50, 52, 54) are interrupted when the imaging detector (18) is fully retracted, and whether beams (50, 52, 54) are present when no signal is applied to the beam emitters (38A).</p> |
