| 摘要 |
<p>A collimator set for a radiotherapy apparatus comprises, in sequence, an aperture collimator 50, a multi-leaf collimator 54 with a pair of opposing arrays of elongate leaves each moveable longitudinally in a Y direction, and a leaf edge collimator 56. To avoid collisions between opposing leaves in the multi-leaf collimator 54, a minimum approach distance is defined which provides a minimum gap between leaves in the Y direction. This creates a gap, which can be covered by the leaf edge collimator 56.</p> |
