Optically Stimulated Luminescence Dosimeters as an Alternative to Radiographic Film for Performing “Head-Wrap” Linac Leakage Measurements
The linac “head-wrap”, where a new or modified linac is covered with radiographic film as a means to identify regions of increased radiation leakage, is an important part of the linac acceptance/commissioning process. However, as radiographic film and developing equipment decrease in availability and increase in cost, a simple, reusable, non-chemical solution becomes increasingly desirable. This study investigated whether discrete dose points measured using optically stimulated luminescence dosimeters (OSLDs) could be used to detect regions of increased radiation, as a substitute for radiographic film. After establishing the ability of the OSLDs to detect leakage and differentiate between high and low leakage doses, via a set of proof-of-concept measurements made in known high and low leakage regions on a Varian iX linac, a systematic evaluation of leakage at the surface of the linac head was undertaken. 60 OSLDs were positioned at regular intervals over the linac head by a member of the research team who was unfamiliar with the expected patterns of linac leakage. The OSLD measurements were able to detect linac head leakage and quantify high and low doses (from 0.6 to 44.7 cGy per 10,000 MU) with sufficient geometric precision to guide the use of an ionisation chamber to measure leakage doses in the patient plane. Reusable point dosimeters such as OSLDs are a promising solution to the problem of diminishing availability of film stock for linac head-wrap tests.
KeywordsRadiation therapy Solid state dosimetry Radiation protection
Compliance with Ethical Standards
The authors declare that they have no conflict of interest. This article does not contain any studies with human participants or animals performed by any of the authors.
- 1.International Electrotechnical Commission: Medical electrical equipment - Part 2–1: Particular requirements for the basic safety and essential performance of electron accelerators in the range 1–50 MeV. 3rd edition. International standard, IEC 60601-2-1 (2009)Google Scholar
- 2.Cramb, J.: Radiation Protection in External Beam Radiotherapy. In: Trapp, J., Kron, T. (eds.) An Introduction to Radiation Protection in Medicine. pp. 171–203. Taylor & Francis, New York (2008)Google Scholar
- 3.Das, I.J.: Introduction. In: Das, I.J. (ed.) Radiochromic Film: Role and Applications in Radiation Dosimetry. pp. 22–25. CRC Press, New York (2017)Google Scholar
- 4.Kairn, T.: Intensity-modulated radiotherapy and volumetric-modulated arc therapy. In: Das, I.J. (ed.) Radiochromic Film: Role and Applications in Radiation Dosimetry. pp. 194–227. CRC Press, New York (2017)Google Scholar
- 5.Aland, T., Moylan, R., Kairn, T., Trapp, J.: Effect of verification imaging on in vivo dosimetry results using Gafchromic EBT3 film. Phys. Medica. 32(11), 1461–1465 (2016). https://doi.org/10.1016/j.ejmp.2016.10.020
- 6.Butson, M.J., Peter, K.N., Cheung, T. and Metcalfe, P.: High sensitivity radiochromic film dose comparisons. Phys. Med. Biol. 47(22), N291-N195 (2002). https://doi.org/10.1088/0031-9155/47/22/402