Transmission block to simplify combined pelvic and inguinal radiation therapy

A homogeneous dose distribution of radiation to inguinal lymph nodes and deep pelvic structures can be achieved with use of a transmission block over the central portion of a large enterior pelvic-inguinal portal, together with a smaller posterior field. This relatively simple technique permits individualization of isodose distributions and eliminates the problems of matching abutting portals. Reproducibility of daily setup and optimization of machine utilization are both improved.