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TU‐D‐T‐617‐05: TG‐43U1 Based Dosimetric Characterization of Model 67‐6520 Cs‐137 Brachytherapy Source
Author(s) -
Wright C,
Duncan R,
Rachabatthula V,
Koona R,
Meigooni A,
Baker C
Publication year - 2005
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 - 10.1118/1.1998409
Subject(s) - thermoluminescent dosimeter , monte carlo method , brachytherapy , imaging phantom , dosimetry , dosimeter , photon , materials science , physics , thermoluminescence , computational physics , nuclear medicine , radiation , medical physics , optics , luminescence , radiation therapy , mathematics , medicine , statistics
Purpose: Dosimetric characteristics of a newly designed Cs‐137 source (Model 67‐6520) by Isotope Product Laboratories were determined using experimental and theoretical methods. These determinations were performed using TG‐43U1 for distances larger than the active length of the source and along‐away matrix for shorter distances. Method and Materials: Radial dose function, dose rate constant, 2D and 1D anisotropy function of the new Cs‐137 source were determined following updated AAPM Task Group 43 (TG‐43U1) recommendations. The experimental setup used for the determination of these parameters consisted of 1.0 × 1.0 × 1.0 mm 3 and 3.2 × 3.2 × 0.89 mm 3 TLD‐100 LiF thermoluminescent dosimeters in Solid Water™ Phantom Material (40 × 40 × 20 cm 3 ). TLD's were read using a Harshaw model 3500 TLD reader. The experimental results were compared to theoretical data using Monte Carlo simulations in liquid and Solid Water™. A Monte Carlo N‐particle Transport Code (MCNP4C2) was used to calculate the dose rate distribution in Solid Water™ and liquid water. This code is capable of accounting for photoelectric, coherent, Compton and pair production interaction processes. The photon interaction cross section file used in this study was DLC‐200 library distributed by the Radiation Shielding Information Computing Center (RSICC). In this study, up to 20×10 6 photons were used for each simulation. Calculations were set up in the same design format as the TLD experiments. Results: The calculated dose rate constant in liquid water and Solid Water™ were found to be 0.961 cGyh −1 U −1 and 0.962 cGyh −1 U −1 , respectively. In addition, there was good agreement between the measured and calculated dose rate constant, radial dose function and the anisotropy function in Solid Water™. Conclusion: The dosimetric characteristics of the IPL 67‐6520 Cs‐137 source were determined using the TG‐43U1 recommendation. The characteristics of the new Cs‐137 source are comparable to the other commercially available sources.