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Practical lookup tables for ensuring target coverage in a clinical setup for skin cancer electron therapy

  • Yongsook C. Lee (a1) and Yongbok Kim (a1)

Abstract

Aim

To create practical lookup tables containing percent depth dose (PDD) and profile parameters of electron beams and to demonstrate clinical application of the lookup tables to skin cancer treatment to ensure target coverage in a clinical setup.

Materials and methods

For 6 and 9 MeV electron energies, PDDs and profiles at clinically relevant depths [i.e., R95 (distal depth of 95% maximum dose), R90, R85 and R80] were measured in water at 100 cm source-to-surface distance for an 10×10 cm2 open field and circular cutouts with diameters of 4, 5, 6, 7 and 8 cm. Then PDD parameters along with profile parameters such as width of isodose lines and penumbra at the clinically relevant depths were determined. Output factors for the cutouts were measured at dmax in water and solid water.

Results

With PDD and profile parameters, dosimetry lookup tables were generated. Based upon the lookup tables, target coverage at prescribed depths was retrospectively reviewed for three skin cancer cases. The lookup tables suggested larger cutouts for adequate target coverage.

Findings

Dosimetry lookup tables for electron beam therapy should include profile parameters at clinically relevant depths and be provided to clinicians to ensure target coverage in a clinical setup.

Copyright

Corresponding author

Correspondence to: Yongbok Kim, Department of Radiation Oncology, The University of Arizona, 1501N Campbell Avenue, P.O. Box 245081, Tucson, AZ 85724-5081, USA. Tel: +1 520 694 7427. Fax: +1 520 694 0228. E-mail: yongbokkim@email.arizona.edu

References

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