David Parsons1, James L Robar2, Daren Sawkey3. 1. Department of Physics and Atmospheric Science, Dalhousie University, 5820 University Avenue, Halifax, Nova Scotia B3H 1V7, Canada. 2. Department of Radiation Oncology and Department of Physics and Atmospheric Science, Dalhousie University, 5820 University Avenue, Halifax, Nova Scotia B3H 1V7, Canada. 3. Varian Medical Systems, Inc., 3120 Hansen Way, Palo Alto, California 94304.
Abstract
PURPOSE: The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. METHODS: VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code, was used to model the Linac treatment head components. Particles were propagated through the lower portion of the treatment head using BEAMnrc. Dose distributions and spectral distributions were calculated using DOSXYZnrc and BEAMdp, respectively. For validation, 6 MV flattened and flattening filter free (FFF) photon beams were generated and compared to measurement for square fields, 10 and 40 cm wide and at dmax for diagonal profiles. Two low-Z targets were investigated: a 2.35 MeV carbon target and the proposed 2.50 MeV commercial imaging target for the TrueBeam platform. A 2.35 MeV carbon target was also simulated in a 2100EX Clinac using BEAMnrc. Contrast simulations were made by scoring the dose in the phosphor layer of an IDU20 aSi detector after propagating through a 4 or 20 cm thick phantom composed of water and ICRP bone. RESULTS: Measured and modeled depth dose curves for 6 MV flattened and FFF beams agree within 1% for 98.3% of points at depths greater than 0.85 cm. Ninety three percent or greater of points analyzed for the diagonal profiles had a gamma value less than one for the criteria of 1.5 mm and 1.5%. The two low-Z target photon spectra produced in TrueBeam are harder than that from the carbon target in the Clinac. Percent dose at depth 10 cm is greater by 3.6% and 8.9%; the fraction of photons in the diagnostic energy range (25-150 keV) is lower by 10% and 28%; and contrasts are lower by factors of 1.1 and 1.4 (4 cm thick phantom) and 1.03 and 1.4 (20 cm thick phantom), for the TrueBeam 2.35 MV/carbon and commercial imaging beams, respectively. CONCLUSIONS: VirtuaLinac is a promising new tool for Monte Carlo modeling of novel target designs. A significant spectral difference is observed between the low-Z target beam on the Clinac platform and the proposed imaging beam line on TrueBeam, with the former providing greater diagnostic energy content.
PURPOSE: The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. METHODS: VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code, was used to model the Linac treatment head components. Particles were propagated through the lower portion of the treatment head using BEAMnrc. Dose distributions and spectral distributions were calculated using DOSXYZnrc and BEAMdp, respectively. For validation, 6 MV flattened and flattening filter free (FFF) photon beams were generated and compared to measurement for square fields, 10 and 40 cm wide and at dmax for diagonal profiles. Two low-Z targets were investigated: a 2.35 MeV carbon target and the proposed 2.50 MeV commercial imaging target for the TrueBeam platform. A 2.35 MeV carbon target was also simulated in a 2100EX Clinac using BEAMnrc. Contrast simulations were made by scoring the dose in the phosphor layer of an IDU20 aSi detector after propagating through a 4 or 20 cm thick phantom composed of water and ICRP bone. RESULTS: Measured and modeled depth dose curves for 6 MV flattened and FFF beams agree within 1% for 98.3% of points at depths greater than 0.85 cm. Ninety three percent or greater of points analyzed for the diagonal profiles had a gamma value less than one for the criteria of 1.5 mm and 1.5%. The two low-Z target photon spectra produced in TrueBeam are harder than that from the carbon target in the Clinac. Percent dose at depth 10 cm is greater by 3.6% and 8.9%; the fraction of photons in the diagnostic energy range (25-150 keV) is lower by 10% and 28%; and contrasts are lower by factors of 1.1 and 1.4 (4 cm thick phantom) and 1.03 and 1.4 (20 cm thick phantom), for the TrueBeam 2.35 MV/carbon and commercial imaging beams, respectively. CONCLUSIONS: VirtuaLinac is a promising new tool for Monte Carlo modeling of novel target designs. A significant spectral difference is observed between the low-Z target beam on the Clinac platform and the proposed imaging beam line on TrueBeam, with the former providing greater diagnostic energy content.
Authors: Ross I Berbeco; Alexandre Detappe; Panogiotis Tsiamas; David Parsons; Mammo Yewondwossen; James Robar Journal: Med Phys Date: 2016-01 Impact factor: 4.071
Authors: Ingrid Valencia Lozano; Mengying Shi; Marios Myronakis; Paul Baturin; Rony Fueglistaller; Pascal Huber; Mathias Lehmann; Daniel Morf; Dianne Ferguson; Matthew W Jacobson; Thomas Harris; Ross I Berbeco; Christopher L Williams Journal: Phys Med Biol Date: 2021-04-16 Impact factor: 4.174
Authors: Mengying Shi; Marios Myronakis; Matthew Jacobson; Dianne Ferguson; Christopher Williams; Mathias Lehmann; Paul Baturin; Pascal Huber; Rony Fueglistaller; Ingrid Valencia Lozano; Thomas Harris; Daniel Morf; Ross I Berbeco Journal: Phys Med Biol Date: 2020-12-02 Impact factor: 4.174
Authors: Mengying Shi; Marios Myronakis; Matthew Jacobson; Mathias Lehmann; Dianne Ferguson; Paul Baturin; Pascal Huber; Rony Fueglistaller; Thomas Harris; Ingrid Valencia Lozano; Christopher Williams; Daniel Morf; Ross I Berbeco Journal: Phys Med Biol Date: 2020-07-06 Impact factor: 4.174
Authors: Lena Griebel; Hans-Ulrich Prokosch; Felix Köpcke; Dennis Toddenroth; Jan Christoph; Ines Leb; Igor Engel; Martin Sedlmayr Journal: BMC Med Inform Decis Mak Date: 2015-03-19 Impact factor: 2.796