Multiadaptive Plan (MAP) IMRT to Accommodate Independent Movement of the Prostate and Pelvic Lymph Nodes.

摘要

Using our current planning margins to the prostate (6 mm posterior and 8 mm elsewhere) and pelvic lymph nodes (5 mm uniform), we found that aligning daily images to the pelvic bones would require a planning margin of the prostate greater what we used clinically. Aligning to the prostate soft tissue, a planning margin of 5 mm to the pelvic lymph nodes is adequate while the planning margin to the prostate can be further reduced. With smaller planning margins or greater magnitudes of the prostate displacement, the proposed adaptive planning method may be beneficial. After comparing three commonly available multi-leaf collimator (MLC) leaf widths of 2.5 mm, 5 mm, and 10 mm, we found that the use of a leaf width of 5 mm was adequate for the proposed adaptive method to compensate for the prostate movement in the longitudinal direction.