Determining radiation dosage in hollow organ, esp. rectum - determining coordinates of points on surface of multiple detector probe and performing spatial transformation

摘要

The coordinate triplets of the radiation detector positions (6,7,8,9,10) in a multi-detector probe (3) are converted from an applicator (12) based reference frame (x,y,z) to a probe reference frame (x',y',z') in which the curved probe (3) lies in a plane y' = constant. The coordinates of the foremost detector (5), the radius of curvature of (3) and the centre of curvature are determined. Using these variables, the tip radius (5) of (4), the diameter of (3), the distance (4) to the first detector (6) and the transform (x,y,z) to (x',y',z'), the coordinates of points on (3) are determined. Further, according to the irradiation plan, the close rate at these points are determined, and by simulation calculation, the maximum dose at the surface of the hollow organ is found. An inverse square law is used for the radiation intensity due to the applicator sources. USE - For gynaecological afterloading therapy with stepped radiative source.