Prog Med Phys.  2018 Mar;29(1):42-46. 10.14316/pmp.2018.29.1.42.

Survey of Radiation Shielding Design Goals and Workload Based on Radiation Safety Report: Tomotherapy Vault

• Cho KH
• Jung JH
• Min CK
• Bae SH
• Moon SK
• Kim ES
• Cho SJ
• Lee R

• KMID: 2411952
• DOI: http://doi.org/10.14316/pmp.2018.29.1.42

Abstract

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 a reas 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.

Keyword

Radiation Shielding; Workload; NCRP-151; Tomotherapy

MeSH Terms

F Factor
Humans

Reference

References

1. NCRP Report No. 151. 2005. Structural Shielding Design and Evaluation for Megavoltage X-and Gamma-Ray Radiotherapy Facilities. Medical Physics.

2. Murai T, Shibamoto Y, Manabe Y, et al. Intensity-modulated radiation therapy using static ports of tomotherapy (TomoDirect): Comparison with the TomoHelical mode. Radiat Oncol. 2013; 8:1–7.

3. Bailat CJ, Baechler S, Moeckli R, Pachoud M, Pisaturo O, Bochud FO. The concept and challenges of TomoTherapy accelerators. Reports Prog Phys. 2011; 74:1–8.

4. Balog J, Lucas D, DeSouza C, Crilly R. Helical tomotherapy radiation leakage and shielding considerations. Med Phys. 2005; 32:710–719.

5. Robinson D, Scrimger JW, Field GC, Fallone BG. Shielding considerations for tometherapy. Med Phys. 2000; 27:2380–2384.

6. Zacarias A, Balog J, Mills M. Radiation shielding design of a new tomotherapy facility. Health Phys. 2006; 91:289–295.

7. NCRP Report No. 49. 1976. Structural Shielding Design and Evaluation for Medical Use of X Rays and Gamma Rays of Energies up to 10 MeV. National Council on Radiation Protection and Measurements (NCRP).

8. NCRP Report No. 51. 1977. Radiation Protection Guidelines for 0.1 –100 MeV Particle Accelerator Facilities: National Council on Radiation Protection and Measurements (NCRP).

9. Martin MC. 2007. Tomotherapy Vault Design. AAPM 2007 Summer School.