| 摘要 |
<p>PROBLEM TO BE SOLVED: To accurately and rapidly align a collimator to the center of a region of interest by determining the position of a collimator assembly in a digital image including a collimator blade and adjusting the position of the blade. SOLUTION: An X-ray digital image 100 showing collimator blades 102-108 being aligned to a region of interest are subjected to segment division into a plurality of bands 116, 117,... in parallel with a horizontal width axial line 112, and a pixel in the bands 116, 117,... is averaged along a vertical axial line 114 to obtain an average vector. The average vector is subjected to convolution, and is subjected to threshold discrimination and comparison, thus determining the line of the blades 102-108, Then, a central position 118 of a known digital image 100 and distance D1-D4 from a region 110 of interest, and angles A1 and A2 are obtained, thus determining the center of a collimator from distance ratios D1/D2 and D3/D4. It is judged whether a collimator has been calibrated or not depending on whether the region 110 of interest is exposed within a specific tolerance or not. When the region 110 is not exposed, the positions of the blades 102-108 are adjusted by an actuator.</p> |
