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On the Evaluation of GATE Monte Carlo Toolkit Performance for the Dosimetry of Ir-192 and I-125 Brachytherapy Sources

E Pappas^1,2*, R Hammoud¹, G Kagadis³, A Sharif¹, A Bakas², P Papadimitroulas³, G Anagnostopoulos², I Kantemiris², G Loudos⁴, N Al Hammadi¹, (1) Hamad Medical Corporation, Doha, Qatar,(2) Techological Education Institute of Athens, Athens,(3) Univ Patras, Rion - Patras, ,(4) Technical Educational Institute of Athens, Aigaleo, Attiki,

SU-E-T-546 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose:
GATE is a Monte Carlo (MC) simulation toolkit based on the Geant4 package widely used for many medical physics applications. The latest version of GATE extends its applications to radiotherapy. Aim of the current study is to evaluate the validity of the code for accurate brachytherapy dosimetry, since this is a prerequisite for its integration within the armamentarium of validated and useful MC codes for this purpose.

Methods:
Towards this aim a number of most commercially used HDR and PDR Ir-192 as well as LDR I-125 brachytherapy sources have been simulated using the GATE MC toolkit. Their specific dosimetric parameters following the TG43 formalism have been derived and subsequently benchmarked versus the clinically used dosimetric data which are incorporated in several Brachytherapy treatment planning systems, and versus several MC codes - such as MCNP, EGSnrc, BrachyDose, GEANT, PENELOPE and MCPT - that have been used extensively for brachytherapy dosimetry.

Results:
The comparison of the GATE derived dosimetric results with the aforementioned established MC codes for the dose rate constant, the radial dose function, the anisotropy function as well as the along and away dose rate tables, exhibited an agreement within 3% in all cases. The use of different cross section libraries, material data tables as well as simulation geometries could justify these differences that are, however, comparable to the discrepancies observed among other MC codes for the same source designs.

Conclusions:
The GATE Monte Carlo toolkit has been benchmarked with well established MC codes in brachytherapy dosimetry and can be safely added within the armamentarium of MC codes used for this purpose. Its versatility and dynamic developing structure promises its use not only in the dosimetric characterization of brachytherapy sources but also in the simulation of real voxel based patient anatomy with the patient related implemented brachytherapy treatment plan.

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