- Email: [email protected]
Abstract ID: 102 Optimization of the unflattened photon beams: A Monte Carlo study
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Abstracts / Physica Medica 42 (2017) 1–50
c Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Republic of Korea d Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine Seoul, Republic of Korea ⇑ Presenting author.
The purpose of this study is to evaluate secondary neutron ambient dose equivalent, which simulated and measured four positions around a plastic water phantom on a couch. We compared and analyzed the secondary neutron dose during proton treatment with scanning mode of each gantry.[1,2]. The volume of the plastic water phantom was 30 30 60 cm3 and was located at the isocenter. The phantom was irradiated by a proton beam at 190 MeV. Proton beams were used to irradiate a volume of 10 10 10 cm3 centered at the isocenter in each nozzle. In addition, WENDI 2 detector was used as a neutron measuring device to measure the neutron ambient dose equivalent. We performed experiments under the same conditions as those of FLUKA simulation. The ambient dose equivalent value was normalized to the maximum value at each nozzle of scanning mode. Each normalized neutron flux in the simulation and experiment showed similar tendencies. We successfully simulated and measured the neutron ambient dose equivalents at four positions generated by the scanning mode. These results prove that the simulation data provides reliable data of the induced neutron dose. Our results provide sufficient reference for the occurrence of secondary neutron during proton therapy.
References 1. Chung KZ et al. The first private-hospital based proton therapy center in Korea; Status of the Proton Therapy Center at Samsung Medical Center. Radiat Oncol J 2015;33(4):1–7. 2. Perez-Andujar A, Newhauser WD, Deluca PM. Neutron Production from beam modifying devices in a modern double scattering proton therapy beam delivery system. Phys Med Biol 2009;54: 993–1008. http://dx.doi.org/10.1016/j.ejmp.2017.09.054
Abstract ID: 101 Comparison of dose calculation between AAA algorithm and Monte Carlo calculation for prostate cancer Belaid Ait Idir, Rachid Khelifi * Université de Blida1, LPTHIR, Département de Physique, Blida, Algeria Presenting author.
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In radiotherapy, the accuracy of dose calculation is very important for a treatment success. Analytical algorithms implemented in commercial Treatment Planning Systems (TPS) achieve this calculation. In order to reduce time calculation; these algorithms do some assumptions, which cause important errors, especially in the cases with high heterogeneities. The aim of our study is to evaluate the AAA analytical algorithm of dose calculation using a Monte Carlo method, which is the most accurate, and considered as a reference in dose calculation. To accomplish this purpose, we started by the modeling of the treatment machine (Varian 2100C LINear ACcelerator) for the photons mode and the energy of 18MV, using EGSnrc Monte Carlo code. After that, we used this model to calculate dose distribution in patients treated for prostate cancer. Finally, the results are compared to those of Eclipse AAA TPS. http://dx.doi.org/10.1016/j.ejmp.2017.09.055
Abstract ID: 102 Optimization of the unflattened photon beams: A Monte Carlo study Maged Mohammed a,b,*, T. El Bardouni b, E. Chakir a a
SIMO-LAB, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences, Tetouan, Morocco ⇑ Presenting author. E-mail: [email protected] b
The components of the medical accelerator play a prominent role to improve the quality of treatment in radiation therapy. This study aims to investigate the physical characteristics, such as surface dose, dose profile, depth dose, energy spectra and dose rate, of 12 MV photon beam with flattening (FF) and without flattening filter (FFF). The Monte Carlo code EGSnrc [1] under the platforms BEAMnrc [2] and DOSXYZ [3] were employed for modeling a Saturne43 Linac to simulate 12 MV photon beam. The results obtained in this study showed that the removal of flattening filter leads to increasing the surface dose by 10.4% and the dose rate increases 4.06 times when flattening filter removed compared to the flattened beam. The dose of unflattened beam at 4 cm from the central axis reduced 15.2% compared to flatten one. Furthermore, we have succeeded to reduce surface dose that increased by removing the flattening filter by a factor of 2.5%. Due to the Air column, between the jaws and the phantom, replaced by Helium column. We conclude that the lower dose in the out-offield, the high dose rate and reducing the head scatter of unflattened beam contribute to add new features to photon beams that will improve the quality of treatment.
References 1. Kawrakow I, Rogers DWO. The EGSnrc code system. NRC Rep. PIRS-701 NRC Ott; 2017. 2. Rogers DWO, et al., BEAMnrc users manual. NRC Rep. PIRS 509, 12; 2017. 3. Walters B, Kawrakow I, Rogers DWO. DOSXYZnrc users manual. NRC Rep. PIRS 794; 2005. http://dx.doi.org/10.1016/j.ejmp.2017.09.056
Abstract ID: 104 Efficiency improvement in proton dose calculations with an equivalent restricted stopping power formalism Daniel Maneval a,b,*, Hugo Bouchard c, Benoıˆt Ozell d, Philippe Després a,b a
Université Laval, Department of Physics, Quebec City, Canada Université Laval, Department of Radiation Oncology and Research Center of CHU de Québec, Quebec City, Canada c Université de Montréal, Département de physique, Montréal, Canada d École polytechnique de Montréal, Département de génie informatique et génie logiciel, Montréal, Canada ⇑ Presenting author. b
To maintain the dose accuracy of Monte Carlo simulations, the mean energy loss calculation usually requires a step restriction (dmax). It leads to a O(n) algorithmic time complexity, where n is the subdivision number imposed by dmax. A new formalism is proposed to accelerate Monte Carlo dose calculations, allowing the removal of dmax in the step selection leading to a O(1) algorithmic time complexity. In this formalism, the midpoint rule of the Newton–Cotes formulae was used to solve the integral equation relating the mean energy loss to the step. The fractional energy loss was obtained with a secant method and a Gauss–Kronrod quadrature, revealing within the midpoint rule the equivalent restricted
Abstracts / Physica Medica 42 (2017) 1–50
c Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Republic of Korea d Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine Seoul, Republic of Korea ⇑ Presenting author.
The purpose of this study is to evaluate secondary neutron ambient dose equivalent, which simulated and measured four positions around a plastic water phantom on a couch. We compared and analyzed the secondary neutron dose during proton treatment with scanning mode of each gantry.[1,2]. The volume of the plastic water phantom was 30 30 60 cm3 and was located at the isocenter. The phantom was irradiated by a proton beam at 190 MeV. Proton beams were used to irradiate a volume of 10 10 10 cm3 centered at the isocenter in each nozzle. In addition, WENDI 2 detector was used as a neutron measuring device to measure the neutron ambient dose equivalent. We performed experiments under the same conditions as those of FLUKA simulation. The ambient dose equivalent value was normalized to the maximum value at each nozzle of scanning mode. Each normalized neutron flux in the simulation and experiment showed similar tendencies. We successfully simulated and measured the neutron ambient dose equivalents at four positions generated by the scanning mode. These results prove that the simulation data provides reliable data of the induced neutron dose. Our results provide sufficient reference for the occurrence of secondary neutron during proton therapy.
References 1. Chung KZ et al. The first private-hospital based proton therapy center in Korea; Status of the Proton Therapy Center at Samsung Medical Center. Radiat Oncol J 2015;33(4):1–7. 2. Perez-Andujar A, Newhauser WD, Deluca PM. Neutron Production from beam modifying devices in a modern double scattering proton therapy beam delivery system. Phys Med Biol 2009;54: 993–1008. http://dx.doi.org/10.1016/j.ejmp.2017.09.054
Abstract ID: 101 Comparison of dose calculation between AAA algorithm and Monte Carlo calculation for prostate cancer Belaid Ait Idir, Rachid Khelifi * Université de Blida1, LPTHIR, Département de Physique, Blida, Algeria Presenting author.
⇑
In radiotherapy, the accuracy of dose calculation is very important for a treatment success. Analytical algorithms implemented in commercial Treatment Planning Systems (TPS) achieve this calculation. In order to reduce time calculation; these algorithms do some assumptions, which cause important errors, especially in the cases with high heterogeneities. The aim of our study is to evaluate the AAA analytical algorithm of dose calculation using a Monte Carlo method, which is the most accurate, and considered as a reference in dose calculation. To accomplish this purpose, we started by the modeling of the treatment machine (Varian 2100C LINear ACcelerator) for the photons mode and the energy of 18MV, using EGSnrc Monte Carlo code. After that, we used this model to calculate dose distribution in patients treated for prostate cancer. Finally, the results are compared to those of Eclipse AAA TPS. http://dx.doi.org/10.1016/j.ejmp.2017.09.055
Abstract ID: 102 Optimization of the unflattened photon beams: A Monte Carlo study Maged Mohammed a,b,*, T. El Bardouni b, E. Chakir a a
SIMO-LAB, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences, Tetouan, Morocco ⇑ Presenting author. E-mail: [email protected] b
The components of the medical accelerator play a prominent role to improve the quality of treatment in radiation therapy. This study aims to investigate the physical characteristics, such as surface dose, dose profile, depth dose, energy spectra and dose rate, of 12 MV photon beam with flattening (FF) and without flattening filter (FFF). The Monte Carlo code EGSnrc [1] under the platforms BEAMnrc [2] and DOSXYZ [3] were employed for modeling a Saturne43 Linac to simulate 12 MV photon beam. The results obtained in this study showed that the removal of flattening filter leads to increasing the surface dose by 10.4% and the dose rate increases 4.06 times when flattening filter removed compared to the flattened beam. The dose of unflattened beam at 4 cm from the central axis reduced 15.2% compared to flatten one. Furthermore, we have succeeded to reduce surface dose that increased by removing the flattening filter by a factor of 2.5%. Due to the Air column, between the jaws and the phantom, replaced by Helium column. We conclude that the lower dose in the out-offield, the high dose rate and reducing the head scatter of unflattened beam contribute to add new features to photon beams that will improve the quality of treatment.
References 1. Kawrakow I, Rogers DWO. The EGSnrc code system. NRC Rep. PIRS-701 NRC Ott; 2017. 2. Rogers DWO, et al., BEAMnrc users manual. NRC Rep. PIRS 509, 12; 2017. 3. Walters B, Kawrakow I, Rogers DWO. DOSXYZnrc users manual. NRC Rep. PIRS 794; 2005. http://dx.doi.org/10.1016/j.ejmp.2017.09.056
Abstract ID: 104 Efficiency improvement in proton dose calculations with an equivalent restricted stopping power formalism Daniel Maneval a,b,*, Hugo Bouchard c, Benoıˆt Ozell d, Philippe Després a,b a
Université Laval, Department of Physics, Quebec City, Canada Université Laval, Department of Radiation Oncology and Research Center of CHU de Québec, Quebec City, Canada c Université de Montréal, Département de physique, Montréal, Canada d École polytechnique de Montréal, Département de génie informatique et génie logiciel, Montréal, Canada ⇑ Presenting author. b
To maintain the dose accuracy of Monte Carlo simulations, the mean energy loss calculation usually requires a step restriction (dmax). It leads to a O(n) algorithmic time complexity, where n is the subdivision number imposed by dmax. A new formalism is proposed to accelerate Monte Carlo dose calculations, allowing the removal of dmax in the step selection leading to a O(1) algorithmic time complexity. In this formalism, the midpoint rule of the Newton–Cotes formulae was used to solve the integral equation relating the mean energy loss to the step. The fractional energy loss was obtained with a secant method and a Gauss–Kronrod quadrature, revealing within the midpoint rule the equivalent restricted