A STUDY ON DOSIMETRIC COMPARISON OF THREE DIMENSIONAL CONFORMAL THERAPY AND VOLUMETRIC MODULATED ARC THERAPY IN LOCALLY ADVANCED RECTALCANCER.

Neoadjuvant Chemo Radio Therapy followed by surgery is the standard of care for locally advanced Rectal carcinoma. Traditionally Radiotherapy is given by using conventional AP/PA elds. This was associated with small bowel toxicity as. Advent of Multi Leaf Collimetor (MLC) had paved way for conformal techniques to reduce the bowel doses with promising results. Newer technologies like Intensity Modulated Radio Therapy ( IMRT) and Volumetric Moulated Arc Therapy (VMAT) have shown to further improve the dose conformity to target and signicantly reduce dose to normal tissues as shown by studies in Head and Neck and Prostate cancers. In this study,we attempt to compare this dosimetric properties like target coverage and normal tissue doses between plan using 3DCRT and VMAT. We hypothesis that VMAT will have better target conformity and better normal tissue sparing.