PURPOSE: Significant dosimetric improvement for radiation therapy using optimized noncoplanar fields has been previously demonstrated.
The purpose here is to study the feasibility of optimized robotic noncoplanar radiation therapy, termed 4π therapy, for prostate cancer treatments on a conventional C-arm linac.
METHODS AND MATERIALS: Twelve low-risk prostate cancer patients previously treated by 2-arc volumetric modulated arc therapy (VMAT) were selected. Forty gray in 5 fractions were prescribed to cover 95% of the prostate planning target volume (PTV). To replan by 4π therapy, a column generation method was used to optimize beam orientations and fluence. A total of 30 beams were selected for each patient.
RESULTS: Both planning methods provided adequate PTV coverage. Compared against VMAT plans, the 4π plan reduced the rectum V50%, V80%, V90%, D1cc, and the penile bulb maximum doses by 50%, 28%, 19% 11%, and 9% (P < .005), respectively, and the mean body dose was reduced from 2.07 Gy to 1.75 Gy (P = .0001). The bladder dose was only slightly reduced.
CONCLUSIONS: By optimizing beam angles and fluences in the noncoplanar solution space, superior prostate treatment plan quality was achieved compared against state of the art VMAT plans. The dosimetric potential for 4π therapy is established on an existing C-arm linac platform.
Written by:
Dong P, Nguyen D, Ruan D, King C, Long T, Romeijn E, Low DA, Kupelian P, Steinberg M, Yang Y, Sheng K. Are you the author?
Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California; Department of Industrial and Operations, University of Michigan, Ann Arbor, Michigan.
Reference: Pract Radiat Oncol. 2014 Jul-Aug;4(4):254-60.
doi: 10.1016/j.prro.2013.10.009
PubMed Abstract
PMID: 25012834
UroToday.com Prostate Cancer Section
