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Dosimetric characteristics of the Leipzig surface applicators used in the high dose rate brachy radiotherapy
Author(s) -
Niu Hongquan,
Hsi Wen C.,
Chu James C. H.,
Kirk Michael C.,
Kouwenhoven Erik
Publication year - 2004
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 - 10.1118/1.1812609
Subject(s) - imaging phantom , dosimetry , materials science , monte carlo method , brachytherapy , nuclear medicine , detector , mosfet , dose rate , optics , physics , transistor , radiation therapy , medical physics , mathematics , medicine , statistics , quantum mechanics , voltage
The nucletron Leipzig applicator is designed for (HDR) Ir192 brachy radiotherapy of surface lesions. The dosimetric characteristics of this applicator were investigated using simulation method based on Monte Carlo N‐particle (MCNP) code and phantom measurements. The simulation method was validated by comparing calculated dose rate distributions of nucletron microSelectron HDR Ir192 source against published data. Radiochromic films and metal‐oxide‐semiconductor field‐effect transistor (MOSFET) detectors were used for phantom measurements. The double exposure technique, correcting the nonuniform film sensitivity, was applied in the film dosimetry. The linear fit of multiple readings with different irradiation times performed for each MOSFET detector measurement was used to obtain the dose rate of each measurement and to correct the source transit‐time error. The film and MOSFET measurements have uncertainties of 3%–7% and 3%–5%, respectively. The dose rate distributions of the Leipzig applicator with 30 mm opening calculated by the validated MC method were verified by measurements of film and MOSFET detectors. Calculated two‐dimensional planar dose rate distributions show similar patterns as the film measurement. MC calculated dose rate at a reference point defined at depth 5 mm on the applicator's central axis is 7% lower than the film and 3% higher than the MOSFET measurements. The dose rate of a Leipzig applicator with 30 mm opening at reference point is 0.241 ± 3 % cGyh − 1U − 1. The MC calculated depth dose rates and profiles were tabulated for clinic use.