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SU‐FF‐T‐03: Accurate Surface Dose Determination for Electronic Brachytherapy Applicators
Author(s) -
Segala J,
Cardarelli G,
Hiatt J,
Curran B,
Sternick E
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3181473
Subject(s) - brachytherapy , dosimetry , radiation treatment planning , ionization chamber , extrapolation , dose profile , radioactive source , materials science , nuclear medicine , biomedical engineering , medical physics , physics , optics , radiation therapy , ionization , radiology , medicine , mathematics , ion , mathematical analysis , quantum mechanics , detector
Purpose: To describe the use of experimental and numerical methods for the accurate determination of dose distributions along surface boundaries of applicators used to deliver electronic brachytherapy. Method and Materials: Numerical models for several sizes of an electronic brachytherapy breast balloon applicator and a vaginal applicator were generated and dose distributions calculated using a general purpose multi particle transport code (FLUKA). The numerical data were compared to experimental measurements obtained with a parallel plate extrapolation ionization chamber and with dose distributions generated by a commercial treatment planning system Results: Close agreement between the numerical model and measured doses were found. Comparison with doses computed using the treatment planning system showed good agreement at a prescription depth of 1.0 cm. Dose deviations as great as 150%, however, were observed at the surface‐tissue interface of the applicators. Conclusions: Using both experimental and numerical methods to determine dose distributions for electronic brachytherapy applicators offers a verifiable, comprehensive procedure in the determination of accurate surface doses. It has been demonstrated that treatment planning systems based on AAPM TG‐43 guidelines, as currently configured do not estimate surface doses accurately when attenuating material is interposed between an electronic brachytherapy x‐ray source and irradiated tissue.