A technique to reduce low dose region for craniospinal irradiation (CSI) with RapidArc and its dosimetric comparison with 3D conformal technique (3DCRT).

We proposed a method to reduce the volume of normal tissues irradiated by low doses in patients receiving CSI with RapidArc (RA) using Avoidance-Sector technique (RA+AS) and to compare its dosimetric implications with RA using full-arc (RA+FA) and 3D conformal technique (3DCRT). Four patients of CSI were retrospectively planned with 3DCRT, RA+FA, and RA+AS. Conformity-Index (CI), Homogeneity-Index (HI), and Paddick Gradient-Index (GI) were calculated.