Treatment plan comparison between Tri-Co-60 magnetic-resonance image-guided radiation therapy and volumetric modulated arc therapy for prostate cancer

Abstract

// Jong Min Park 1, 2, 3, 4 , So-Yeon Park 1, 2, 3 , Chang Heon Choi 1, 2, 3 , Minsoo Chun 1, 2, 3 , Jin Ho Kim 1, 2, 3 and Jung-In Kim 1, 2, 3 1 Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea 2 Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea 3 Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea 4 Robotics Research Laboratory for Extreme Environments, Advanced Institutes of Convergence Technology, Suwon, Republic of Korea Correspondence to: Jung-In Kim, email: [email protected] Keywords: prostate cancer, magnetic-resonance image-guided radiation therapy, volumetric modulated arc therapy Received: June 13, 2017      Accepted: July 25, 2017      Published: August 08, 2017 ABSTRACT To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) with magnetic-resonance image-guided radiation therapy compared with volumetric-modulated arc therapy (VMAT) for prostate cancer. Twenty patients with intermediate-risk prostate cancer, who received radical VMAT were selected. Additional tri-Co-60 IMRT plans were generated for each patient. Both primary and boost plans were generated with tri-Co-60 IMRT and VMAT techniques. The prescription doses of the primary and boost plans were 50.4 Gy and 30.6 Gy, respectively. The primary and boost planning target volumes (PTVs) of the tri-Co-60 IMRT were generated with 3 mm margins from the primary clinical target volume (CTV, prostate + seminal vesicle) and a boost CTV (prostate), respectively. VMAT had a primary planning target volume (primary CTV + 1 cm or 2 cm margins) and a boost PTV (boost CTV + 0.7 cm margins), respectively. For both tri-Co-60 IMRT and VMAT, all the primary and boost plans were generated that 95% of the target volumes would be covered by the 100% of the prescription doses. Sum plans were generated by summation of primary and boost plans. In sum plans, the average values of V70 Gy of the bladder of tri-Co-60 IMRT vs. VMAT were 4.0% ± 3.1% vs. 10.9% ± 6.7%, ( p < 0.001). Average values of V70 Gy of the rectum of tri-Co-60 IMRT vs. VMAT were 5.2% ± 1.8% vs. 19.1% ± 4.0% ( p < 0.001). The doses of tri-Co-60 IMRT delivered to the bladder and rectum were smaller than those of VMAT while maintaining identical target coverage in both plans.