Abstract
Purpose
The dose changes in the buildup region and beam attenuation by a carbon fiber tabletop were investigated for 6-and 18-MV photon beams.
Materials and methods
Measurements were performed for 2 × 2 cm to 40 × 40 cm field sizes. The surface dose and percentage depth doses (PDD) were measured by a Markus parallel plate chamber. Attenuation measurements were made at the cylindrical phantom for 180° rotation of the beam.
Results
A carbon fiber tabletop increases the surface dose from 7.5% to 63.0% and from 4% to 43% for small fields at 6 and 18 MV, respectively. The increase was nearly fivefold for the 10 × 10 cm field and nearly twofold for the 40 × 40 cm field. Beam attenuation of the tabletop varies from 3.0% to 5.6% for 180° and 120° gantry angles for 6 MV.
Conclusion
The carbon fiber tabletop significantly decreases the skin-sparing effect. The dosimetric effect of the tabletop may be higher, especially for the intensity-modulated radiation therapy depending on the beam orientation. Attenuation should be considered and corrected such as any material under the patient at the treatment planning stage.
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Meydanci, T.P., Kemikler, G. Effect of a carbon fiber tabletop on the surface dose and attenuation for high-energy photon beams. Radiat Med 26, 539–544 (2008). https://doi.org/10.1007/s11604-008-0271-6
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DOI: https://doi.org/10.1007/s11604-008-0271-6