title: GGEMS-Brachy: GPU GEant4-based Monte Carlo simulation for brachytherapy applications.
abstract: In brachytherapy, plans are routinely calculated using the AAPM TG43 formalism which considers the patient as a simple water object. An accurate modeling of the physical processes considering patient heterogeneity using Monte Carlo simulation (MCS) methods is currently too time-consuming and computationally demanding to be routinely used. In this work we implemented and evaluated an accurate and fast MCS on Graphics Processing Units (GPU) for brachytherapy low dose rate (LDR) applications. A previously proposed Geant4 based MCS framework implemented on GPU (GGEMS) was extended to include a hybrid GPU navigator, allowing navigation within voxelized patient specific images and analytically modeled (125)I seeds used in LDR brachytherapy. In addition, dose scoring based on track length estimator including uncertainty calculations was incorporated. The implemented GGEMS-brachy platform was validated using a comparison with Geant4 simulations and reference datasets. Finally, a comparative dosimetry study based on the current clinical standard (TG43) and the proposed platform was performed on twelve prostate cancer patients undergoing LDR brachytherapy. Considering patient 3D CT volumes of 400  × 250  × 65 voxels and an average of 58 implanted seeds, the mean patient dosimetry study run time for a 2% dose uncertainty was 9.35 s (≈500 ms 10(-6) simulated particles) and 2.5 s when using one and four GPUs, respectively. The performance of the proposed GGEMS-brachy platform allows envisaging the use of Monte Carlo simulation based dosimetry studies in brachytherapy compatible with clinical practice. Although the proposed platform was evaluated for prostate cancer, it is equally applicable to other LDR brachytherapy clinical applications. Future extensions will allow its application in high dose rate brachytherapy applications.
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Lemaréchal
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Bert
authors.affiliation: Service de radiothérapie, CHRU Brest, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Falconnet
authors.affiliation: Département de radio-oncologie and Centre de recherche du CHU de Québec, Québec QC, Canada.|Départment de physique, de genie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec QC, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Després
authors.affiliation: Départment de physique, de genie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec QC, Canada.|Service d'urologie, CHRU Brest, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Valeri
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.|Service de radiothérapie, CHRU Brest, France.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schick
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.|Service de radiothérapie, CHRU Brest, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Pradier
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Garcia
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.|Service de radiothérapie, CHRU Brest, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Boussion
authors.affiliation: LaTIM, UMR1101, INSERM, CHRU Brest, France.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Visvikis
mesh_terms: D000465:Algorithms; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D008297:Male; D009010:Monte Carlo Method; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*