Prog Med Phys.  2017 Jun;28(2):45-48. 10.14316/pmp.2017.28.2.45.

Assessment of Radiation Dose from Radioactive Wedge Filters during High-Energy X-Ray Therapy

• Back GM
• Park SH
• Kim TH

• KMID: 2388207
• DOI: http://doi.org/10.14316/pmp.2017.28.2.45

Abstract

This paper evaluated the amount of radiation generated by wedge filters during radiation therapy using a high-energy linear accelerator, and the dose to the worker during wedge replacement. After 10-MV photon beam was irradiated with wedge filter, the wedge was removed from the linear accelerator, and the dose rate and energy spectrum were measured. The initial measurement was approximately 1 uSv/h, and the radiation level was reduced to 0.3 uSv/h after 6 min. The effective half-life derived from the dose rate measurement was approximately 3.5 min, and the influence of AI-28 was about 53%. From the energy spectrum measurements, a peak of 1,799 keV was measured for AI-28, while the peak for Co-58 was not measured in the control room. The peaks for Au-106 and Cd-105 were found only measurement was done without wedge removement from the linear accelerator. The additional doses received by the radiation worker during wedge replacement were estimated to be 0.08−0.4 mSv per year.

Keyword

Radiation dose; Wedge filter; Linear accelerator

MeSH Terms

Half-Life
Particle Accelerators
X-Ray Therapy*

Figure

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  Fig. 1. Measurement of dose rate using GM detector and activated wedge filter.

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  Fig. 2. Measurement of energy spectrum using NaI scintillator detector.

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  Fig. 3. Measured dose rate of activated wedge after 5-Gy irradiation at various field sizes.

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  Fig. 4. Measured energy spectrum from activated wedge after 5-Gy irradiation.

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