对三维体数据“拍X光”的技术

A Method of 3-D Perspective

本文介绍了一种对三维体数据“拍Ｘ刀”的技术，它是利用三角关系的推导得到的。在等中心放射治疗中，可照射弧的自动选择、平均照射深度的计算和射束视野的显示，都可以依靠这一技术实现．

We developed a perspective method for 3-D volume data of brain CT image. At first, we definedthe coordinate system. It is not a kind of coordinate cystem already used before, such as BRW system. It relates tothe CT slice, but not to the head ring. Then two kinds of angle (beam's couch angle and beam's gantry angle )were given definition. These two kinds of angle are different from couch angle and gantry angle which were wellused in radiation oncology. With these kinds of angle we defined, the calculation in the method was simple andclear. After mathematical calculation, we obtained some useful formulas. This method can be widely used in radiation oncology treatment planning, Such as automatic selection of beam arcs, calculation of beau's depth and getting beam's eye view (2-D). It has been well used in the research of X-ray knife.