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Geometric Evaluation of Patient-Specific 3D Bolus from 3D Printed Mold and Casting Method for Radiation Therapy
Prog. Med. Phys. 2019;30(1):32-38
Published online March 31, 2019
© 2019 Korean Society of Medical Physics.

Hyun Joon An1,2, Myeong Soo Kim1,2, Jiseong Kim1,2, Jaeman Son1,2, Chang Heon Choi1,2,3, Jong Min Park1,2,3,4, Jung-in Kim1,2,3

1Department of Radiation Oncology, Seoul National University Hospital, 2Biomedical Research Institute, Seoul National University Hospital, 3Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 4Robotics Research Laboratory for Extreme Environments, Advanced Institutes of Convergence Technology, Suwon, Korea
Correspondence to: Jung-in Kim, (madangin@gmail.com)
Tel: 82-2-2072-3573, Fax: 82-2-3410-2619
Received January 29, 2019; Revised March 15, 2019; Accepted March 19, 2019.
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
Purpose: The objective of this study is to evaluate the geometrical accuracy of a patient-specific bolus based on a three-dimensional (3D) printed mold and casting method.
Materials and Methods: Three breast cancer patients undergoing treatment for a superficial region were scanned using computed tomography (CT) and a designed bolus structure through a treatment planning system (TPS). For the fabrication of patient-specific bolus, we cast harmless certified silicone into 3D printed molds. The produced bolus was also imaged using CT under the same conditions as the patient CT to acquire its geometrical shape. We compared the shapes of the produced bolus with the planned bolus structure from the TPS by measuring the average distance between two structures after a surface registration.
Results and Conclusions: The result of the average difference in distance was within 1 mm and, as the worst case, the absolute difference did not exceed ±2 mm. The result of the geometric difference in the cross-section profile of each bolus was approximately 1 mm, which is a similar property of the average difference in distance. This discrepancy was negligible in affecting the dose reduction. The proposed fabrication of patient-specific bolus is useful for radiation therapy in the treatment of superficial regions, particularly those with an irregular shape.
Keywords : Bolus, Patient specific bolus, 3D printing, Dose build up, Geometric analysis


March 2019, 30 (1)