Concurrent boost radiotherapy as preoperative treatment for locally advanced rectal carcinoma: a new beam arrangement.

Purpose: To describe a new beam arrangement for preoperative concurrent boost radiotherapy in locally advanced rectal carcinoma.

Material And Methods: Three different volumes, ie posterior pelvis, total mesorectal space, and gross tumor volume plus 2 cm, are selected to receive radiation doses of 47 Gy, 51 Gy, and 54 Gy, respectively, in 24 fractions. There are two prerequisites for the use of such a radiotherapy schedule: complete displacement of the small bowel outside the boost volume, and horizontal positioning of the rectal long axis.