A dosimetric study of Leipzig applicators
- Radiotherapy Department, La Fe Hospital, Valencia (Spain)
- Department of Atomic, Molecular, and Nuclear Physics, University of Valencia and IFIC-CSIC, Burjassot (Spain)
- Grupo IMO-SFA, Madrid (Spain)
- CND, Centro Nacional de Dosimetria, Valencia (Spain)
- FIVO, Fundacion Instituto Valenciano de Oncologia, Valencia (Spain)
Purpose: To obtain the absolute dose-rate distribution in liquid water for all six cup-shaped Leipzig applicators by means of an experimentally validated Monte Carlo (MC) code. These six applicators were used in high-dose-rate (HDR) afterloaders with the 'classic' and v2 {sup 192}Ir sources. The applicators have an inner diameter of 1, 2, and 3 cm, with the source traveling parallel or perpendicular to the contact surface. Methods and materials: The MC GEANT4 code was used to obtain the dose-rate distribution in liquid water for the six applicators and the two HDR source models. To normalize the applicator output factors, a MC simulation for the 'classic' and v2 sources in air was performed to estimate the air-kerma strength. To validate this specific application and to guarantee that realistic source-applicator geometry was considered, an experimental verification procedure was implemented in this study, in accordance with the TG43U1 recommendations. Thermolumniscent dosimeter chips and a parallel plate ionization chamber in a polymethyl methacrylate (PMMA) phantom were used to verify the MC results for the six applicators in a microSelectronHDR afterloader with the 'classic' source. Dose-rate distributions dependence on phantom size has been evaluated using two different phantom sizes. Results: Percentage depth dose and off-axis profiles were obtained normalized at a depth of 3 mm along the central axis for both phantom sizes. A table of output factors, normalized to 1 U of source kerma strength at this depth, is presented. The dose measured in the PMMA phantom agrees within experimental uncertainties with the dose obtained by the MC GEANT4 code calculations. The phantom size influence on dose-rate distributions becomes significant at depths greater than 5 cm. Conclusions: MC-detailed simulation was performed for the Nucletron Leipzig HDR applicators. The matrix data obtained, with a grid separation of 0.5 mm, can be used to build a dataset in a convenient format to model these distributions for routine use with a brachytherapy treatment planning system.
- OSTI ID:
- 20698475
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 62, Issue 2; Other Information: DOI: 10.1016/j.ijrobp.2005.02.028; PII: S0360-3016(05)00345-7; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
Similar Records
Technique for routine output verification of Leipzig applicators with a well chamber
Dosimetric characteristics of the Leipzig surface applicators used in the high dose rate brachy radiotherapy