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Survey of Radiation Shielding Design Goals and Workload Based on Radiation Safety Report: Tomotherapy Vault
Prog. Med. Phys. 2018;29(1):42-46
Published online March 31, 2018
© 2018 Korean Society of Medical Physics.

Kwang Hwan Cho*, Jae Hong Jung*, Chul Kee Min*, Sun Hyun Bae*, Seong Kwon Moon*, Eun Seog Kim*, Sam Ju Cho, Rena Lee

*Department of Radiation Oncology, Soonchunhyang University, College of Medicine, Cheonan, Department of Biomedical Engineering, Ewha Womans University School of Medicine, Seoul, Korea
Correspondence to: Jae Hong Jung(
Tel: 82-32-621-5783
Fax: 82-32-621-5885
Received March 14, 2018; Revised March 28, 2018; Accepted March 30, 2018.
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The purpose of this study was to perform a survey of the radiation shielding design goals (P) and workload (W) based on the radiation safety reports concerned with structural shielding design for the IMRT treatment technique in Tomotherapy vaults. The values of the P and W  factors as well as of a verified concrete thickness of the ceiling, bottom, sidewalls (sidewall-1 and sidewall-2), and door have been obtained from radiation safety reports for a total of 16 out of 20 vaults. The recommended and most widely used report for P  values was the NCRP No. 151 report, which stated that the P  factor in controlled and uncontrolled areas was 0.1 and 0.02 mSv/week, respectively. The range of the W  factor was 600~14,720 Gy/week. The absorbed dose delivered per patient was 2~3 Gy. The maximum number of patients treated per day was 10~70. The quality assurance (QA) dose was 100~1,000 Gy/week. Fifteen values of the IMRT factor (F) were mostly used but a maximum of 20 values was also used. The concrete thickness for primary structures including the ceiling, bottom, sidewalls, and door was sufficient for radiation shielding. The P  and W  factors affect the calculation of the structural shielding design, and several parameters, such as the absorbed dose, patients, QA dose, days  and F  factor can be varied according to the type of shielding structure. To ensure the safety of the radiation shielding, it is necessary to use the NCRP No. 151 report for the standard recommendation values.
Keywords : Radiation Shielding, Workload, NCRP-151, Tomotherapy

March 2018, 29 (1)