A New Technique for Whole Craniospinal Irradiation (WCSI)

Chang, Hyesook

Abstract

To irradiate the entire neuroaxis, bilateral parallel opposed brain fields and direct posterior spinal field have been utilized and radiation dose at the junction between abutting fields has been extensilvely studied. And several workable methods were reported to achieve uniform dose at a desired depth at the junction between abutting fields whose central axis are coplanar. But the dose distribution at the junction of orthogonal fields has been a persistent problem in radiation oncology. Author describes a new method to solve the junction problem between abutting fields whose central axis are orthogonal. Author utilized split beam/comllimator rotation or collimator/couch rotation to avoid hot or cold spots that may arise from beam divergence. Author achieved accurate and homogeneous dose distribution by matching the 50% isodose line at the junction between orthogonal central axis beam fields.