Defining the Optimal Time of Adaptive Replanning in Prostate Cancer Patients with Weight Change during Volumetric Arc Radiotherapy: A Dosimetric and Mathematical Analysis Using the Gamma Index. (18th December 2017)

• Record Type: Journal Article
• Authors: Choi, Hoon Sik; Jo, Guang Sub; Chae, Jong Pyo; Lee, Sang Bong; Kim, Chul Hang; Jeong, Bae Kwon; Jeong, Hojin; Lee, Yun Hee; Ha, In Bong; Kang, Ki Mun; Song, Jin Ho
• Other Names: Ferrigno Giancarlo Academic Editor.
• Is Part Of: Computational and mathematical methods in medicine. Volume 2017(2017)
• Publication Date: 2017-12-18
• Subjects: Medicine -- Computer simulation -- Periodicals; Medicine -- Mathematical models -- Periodicals; 610.11
• DOI: 10.1155/2017/4149591
• Languages: English
• ISSNs: 1748-670X

Abstract

Abstract : We evaluated the changes in the dose distribution of radiation during volumetric arc radiotherapy (VMAT), to determine the right time for adaptive replanning in prostate cancer patients with progressive weight (WT) changes. Five prostate cancer patients treated with VMAT were selected for dosimetric analysis. On the original computed tomography images, nine artificial body contours were created to reflect progressive WT changes. Combined with three different photon energies (6, 10, and 15-MV), 27 comparable virtual VMAT plans were created per patient. The dosimetric analysis included evaluation of target coverage ( D 95 %, D max ), conformity index, homogeneity index, and organs at risk doses. The dose differences among the plans were determined using the gamma index analysis and were compared with the dosimetric analysis. Mean D 95 % became lower than 98% when body contour expanded by 2.0 cm or more and D max became higher than 107% when body contour contracted by 1.5 cm or more in 10-MV plans. This cut-off values correlated well with gamma index analysis results. Adaptive replanning should, therefore, be considered if the depth of body contour becomes 1.5 cm smaller (WT loss) or 2.0 cm larger (WT gain) in patients treated by VMAT with 10-MV photons.