Carbon Fiber Belly Board Quality Assurance in Radiotherapy

GenesisCare,1316 Nelson Avenue, Modesto CA 95350,USA

^*Corresponding Author

Aime M. Gloi

GenesisCare

1316 Nelson Avenue, Modesto CA 95350

USA

Phone: 209-575-5870

Fax: 209-575-5870

Email: agloi7288@gmail.com

Abstract

Background: Carbon fiber belly board is the newer immobilization device that has earned recognition in sparing small bowel during prone pelvic irradiation. It is characterized by mechanical strength, a smooth rigidity, and a low specific density. In this study, the beam attenuation for a 10x10 cm² field size was calculated for 6 and 18 MV photons beam.

Methods: A Farmer ion chamber of 0.6 cc volume, slabs of solid water phantom, and an electrometer were used to measure the relative exit dose with or without the carbon fiber belly board at variable gantry angles. The measurements were performed at 100 cm SSD, and 100 MU were delivered.

Results: The average beam attenuation amounted to 3.46±1.53% and 2.22±0.89% for 6 and 18 MV, respectively. The highest attenuation was obtained at 130^o and the lowest at 120^o gantry angle for both energies.

Conclusion: Irradiating through carbon fiber immobilization devices triggered a variation of the beam attenuation at different gantry angles. As a result, there is a loss of skin-sparing effect with megavoltage photon beam. Therefore, special attention is needed in the treatment planning system when using these carbon fiber immobilization devices.

Keywords: Carbon Fiber, Quality assurance, Beam attenuation

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