search for




 

Dosimetric Evaluation of Plans Converted with the DVH-Based Plan Converter
Prog. Med. Phys. 2018;29(4):157-163
Published online December 31, 2018
© 2018 Korean Society of Medical Physics.

Minsoo Chun*,†,‡, Chang Heon Choi*,†,‡, Jung-in Kim*,†,‡, Jeongmin Yoon*,†,‡, Sung Young Lee*,†, Ohyun Kwon*,†, Jaeman Son*,†, Hyun Joon An*,†, Seong-Hee KangΙΙ, Jong Min Park*,†,‡,§

*Department of Radiation Oncology, Seoul National University Hospital, Biomedical Research Institute, Seoul National University Hospital, Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, §Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, ΙΙDepartment of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam, Korea
Correspondence to: Jong Min Park (leodavinci@naver.com)
Tel: 82-2-2072-2527  Fax: 82-2-2072-2527
Received November 28, 2018; Revised December 14, 2018; Accepted December 14, 2018.
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Plans converted using dose-volume-histogram-based plan conversion (DPC) were evaluated by comparing them to the original plans. Changes in the dose volumetric (DV) parameters of five volumetric modulated arc therapy (VMAT) plans for head and neck (HN) cancer and five VMAT plans for prostate cancer were analyzed. For the HN plans, the homogeneity indices (HIs) of the three planning target volumes (PTV) increased by 0.03, 0.02, and 0.03, respectively, after DPC. The maximum doses to the PTVs increased by 1.20, 1.87, and 0.92 Gy, respectively, after DPC. The maximum doses to the optic chiasm, optic nerves, spinal cord, brain stem, lenses, and parotid glands increased after DPC by approximately 4.39, 3.62, 7.55, 7.96, 1.77, and 6.40 Gy, respectively. For the prostate plans after DPC, the HIs for the primary and boost PTVs increased by 0.05 and 0.03, respectively, and the maximum doses to each PTV increased by 1.84 and 0.19 Gy, respectively. After DPC, the mean doses to the rectum and femoral heads increased by approximately 6.19 and 2.79 Gy, respectively, and those to the bladder decreased by 0.20 Gy when summing the primary and boost plans. Because clinically unacceptable changes were sometimes observed after DPC, plans converted by DPC should be carefully reviewed before actual patient treatment.
Keywords : DVH-based plan converter, Volumetric modulated arc therapy, Step-and-shoot IMRT, Dose-volumetric parameters, Plan quality


March 2019, 30 (1)