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Abstract ID: 175 A EBT3 film calibration approach for the validation of a Monte Carlo internal dosimetry framework
Abstracts / Physica Medica 42 (2017) 1–50
The application has been developed with the Geant4 Monte Carlo toolkit. It has been designed in a modular way in order to easily switch on/off geometrical components according to different experimental setups. The application has been preliminary validated comparing particle tracks to results obtained with reference codes for transport of particles in magnetic fields, with a good agreement. Specifically, energy distributions, lateral beam profiles and longitudinal dose distributions in the in-air final section were simulated for proton beams with energies ranging between 5 and 60 MeV. A transmission efficiency of more than 10% was calculated at 60 MeV, which implies the delivery of up to tens of cGy per pulse at the sample irradiation point. Assuming a repetition rate of 1 Hz, between 1 and 10 Gy/min can be potentially achieved in such conditions. These results are of great importance to assess the possibility of carrying out in vitro and in vivo radiobiology experiments aiming to demonstrate the possible future use of optically accelerated beams for therapeutic purposes.
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was <1%. Discussion and conclusion: The optimal orthovoltage beam quality for the calibration of EBT3 film to use with 177Lu was found. The f(Q) does not show a strong kVp dependence in the range explored, and calibration can be performed with a beam having an effective energy of approximately 140 keV and a quality of 3 mm Cu (HVL). This represents the first step towards the validation of a fast GPU-based, in-house Monte Carlo code dedicated to accurate internal dosimetry in nuclear medicine. http://dx.doi.org/10.1016/j.ejmp.2017.09.091
Abstract ID: 177 A robust Monte Carlo treatment planning optimization algorithm for dose painting clinical implementation Elisa Jiménez-Ortega a,b,*, Ana Ureba b,c, Ana Rita Barbeiro a,b, Marcin Balcerzyk d, Ángel Parrado Gallego d, Amadeo Wals-Zurita e, Francisco Javier García-Gómez f, Antonio Leal a,b a
References 1. Cirrone GAP et al. Nucl Instrum Methods Phys Res Sect A 2015;796:99–103. 2. Romano F et al. Nucl Instrum Methods Phys Res Sect A 2016;829:153–8. 3. Pipek et al. Proceedings of the 3rd Elimed Workshop on JINST. In Press. http://dx.doi.org/10.1016/j.ejmp.2017.09.090
Abstract ID: 175 A EBT3 film calibration approach for the validation of a Monte Carlo internal dosimetry framework Andrea Frezza a,*, Romain Espagnet a, Corentin Desport a, Daniel Maneval a, Philippe Després a,b a
Department of Physics, Engineering Physics and Optics and Cancer Research Center, Université Laval, Quebec city, QC G1V 0A6, Canada b Department of Radiation Oncology and Research Center of CHU de Québec, Université Laval, Quebec city, QC G1R 2J6, Canada ⇑ Presenting author. Context and objectives: Recent studies have shown the potential benefits of using 177Lu-based Peptide Receptor Radionuclide Therapy (PRRT) in neuroendocrine tumors. For 177Lu-based and other radionuclide therapies, it appears that a robust Monte Carlo-based internal dosimetry framework is highly desirable. Gafchromic EBT3 films can potentially contribute to the validation of such a dosimetry framework, but require an appropriate calibration procedure to account for their energy dependence. Monte Carlo simulations were used to investigate this dependence with 177Lu, and to develop a film calibration procedure with an orthovoltage beam having a quality (Q) and a similar energy dependence. Methods: The physical quantity evaluated in this work was the film equivalent absorbed dose to water f(Q). This was obtained with Geant4 simulations as the ratio of the absorbed dose in water to the absorbed dose in the film displacing a water volume. f(Q) was calculated with different orthovoltage beams and with a 177Lu source placed in a water filled Jaszczak phantom. X-ray beam qualities ranging from 2.24 to 3.22 mm Cu (HVL) were tested, corresponding to peak voltages of [220–300] kVp and effective energies of [115–142] keV. The simulation input spectra were obtained with the SpeckCalc software. 177Lu disintegrations were simulated with Geant4 RadioactiveDecay5.1.1 data. Results: A minimal difference of 0.4% in f(Q) was obtained between 177Lu and an orthovoltage beam quality of 3.07 mm Cu (HVL) having an effective energy of 138 keV (300 kVp). For beams with effective energies ranging from 136 to 142 keV, this difference
Dpto. Fisiología Médica y Biofísica, University of Seville, Seville, Spain Instituto de Biomedicina de Sevilla, Seville, Spain c Medical Radiation Physics, Stockholm University, Karolinska Institutet, Stockholm, Sweden d Centro Nacional de Aceleradores (CNA), Universidad de Sevilla, Junta de Andalucía, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain e Hospital Universitario Virgen Macarena, Servicio de Radioterapia, Seville, Spain f Hospital Universitario Virgen Macarena, Servicio de Medicina Nuclear, Seville, Spain ⇑ Presenting author. b
Purpose. In order to start accurate clinical trials based on treatments more aggressive than traditional margin approaches, a robust optimization algorithm has been developed for dose calculation full Monte Carlo-based. Specifically, the algorithm is presented here to manage uncertainties on dose painting from PET/CT image data. Material and Methods. CARMEN platform [1] was updated to allow heterogeneous dose prescription by means the recurrent both approaches. For the approach considered as true dose painting by number (tDPBN) where the restriction of dose to volumes makes no sense, it was necessary to develop a novel algorithm including an optimization method at the voxel level under Lineal Programming (LP) formulation [2]. For the approach based on the discretization of functional information into several clusterings (DPBN), instead of a recurrent equidistant isolevel, we implemented several algorithms able to reflect the diffuse and multifocal nature of the uptake regions. For this study, the affinity propagation proposed by Foster [3] in order to reduce random errors due to the PET images registration process. Full Monte Carlo simulations were performed for preoptimization and final dose calculation for taking into account the interactions of particles by means an explicit transport along the beam modifiers in the linac head. Axesse/Synergy linacs of Elekta were modellized with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code, a modified version of DOSXYZnr for calculate the specific beamlet dose contribution on each voxel. A grid calculation consisting on 256 256 voxels per slice was used from the interpolation of PET/CT images reconstructed by keeping a compromise with EARL (ResEARch4LifeÒ) accreditation requirements. Linear Programming formulation at voxel level allowed stablishing a tractable robustness of the uncertainties related to the heterogeneous dose prescription, imposing lower and upper-bound constraints to each voxel in accordance to the clustering volume to which they belong. For tDPBN, an inverse planning schema was previously developed [4]. For DPBN by clusterings approach, a specific direct aperture opti-
The application has been developed with the Geant4 Monte Carlo toolkit. It has been designed in a modular way in order to easily switch on/off geometrical components according to different experimental setups. The application has been preliminary validated comparing particle tracks to results obtained with reference codes for transport of particles in magnetic fields, with a good agreement. Specifically, energy distributions, lateral beam profiles and longitudinal dose distributions in the in-air final section were simulated for proton beams with energies ranging between 5 and 60 MeV. A transmission efficiency of more than 10% was calculated at 60 MeV, which implies the delivery of up to tens of cGy per pulse at the sample irradiation point. Assuming a repetition rate of 1 Hz, between 1 and 10 Gy/min can be potentially achieved in such conditions. These results are of great importance to assess the possibility of carrying out in vitro and in vivo radiobiology experiments aiming to demonstrate the possible future use of optically accelerated beams for therapeutic purposes.
37
was <1%. Discussion and conclusion: The optimal orthovoltage beam quality for the calibration of EBT3 film to use with 177Lu was found. The f(Q) does not show a strong kVp dependence in the range explored, and calibration can be performed with a beam having an effective energy of approximately 140 keV and a quality of 3 mm Cu (HVL). This represents the first step towards the validation of a fast GPU-based, in-house Monte Carlo code dedicated to accurate internal dosimetry in nuclear medicine. http://dx.doi.org/10.1016/j.ejmp.2017.09.091
Abstract ID: 177 A robust Monte Carlo treatment planning optimization algorithm for dose painting clinical implementation Elisa Jiménez-Ortega a,b,*, Ana Ureba b,c, Ana Rita Barbeiro a,b, Marcin Balcerzyk d, Ángel Parrado Gallego d, Amadeo Wals-Zurita e, Francisco Javier García-Gómez f, Antonio Leal a,b a
References 1. Cirrone GAP et al. Nucl Instrum Methods Phys Res Sect A 2015;796:99–103. 2. Romano F et al. Nucl Instrum Methods Phys Res Sect A 2016;829:153–8. 3. Pipek et al. Proceedings of the 3rd Elimed Workshop on JINST. In Press. http://dx.doi.org/10.1016/j.ejmp.2017.09.090
Abstract ID: 175 A EBT3 film calibration approach for the validation of a Monte Carlo internal dosimetry framework Andrea Frezza a,*, Romain Espagnet a, Corentin Desport a, Daniel Maneval a, Philippe Després a,b a
Department of Physics, Engineering Physics and Optics and Cancer Research Center, Université Laval, Quebec city, QC G1V 0A6, Canada b Department of Radiation Oncology and Research Center of CHU de Québec, Université Laval, Quebec city, QC G1R 2J6, Canada ⇑ Presenting author. Context and objectives: Recent studies have shown the potential benefits of using 177Lu-based Peptide Receptor Radionuclide Therapy (PRRT) in neuroendocrine tumors. For 177Lu-based and other radionuclide therapies, it appears that a robust Monte Carlo-based internal dosimetry framework is highly desirable. Gafchromic EBT3 films can potentially contribute to the validation of such a dosimetry framework, but require an appropriate calibration procedure to account for their energy dependence. Monte Carlo simulations were used to investigate this dependence with 177Lu, and to develop a film calibration procedure with an orthovoltage beam having a quality (Q) and a similar energy dependence. Methods: The physical quantity evaluated in this work was the film equivalent absorbed dose to water f(Q). This was obtained with Geant4 simulations as the ratio of the absorbed dose in water to the absorbed dose in the film displacing a water volume. f(Q) was calculated with different orthovoltage beams and with a 177Lu source placed in a water filled Jaszczak phantom. X-ray beam qualities ranging from 2.24 to 3.22 mm Cu (HVL) were tested, corresponding to peak voltages of [220–300] kVp and effective energies of [115–142] keV. The simulation input spectra were obtained with the SpeckCalc software. 177Lu disintegrations were simulated with Geant4 RadioactiveDecay5.1.1 data. Results: A minimal difference of 0.4% in f(Q) was obtained between 177Lu and an orthovoltage beam quality of 3.07 mm Cu (HVL) having an effective energy of 138 keV (300 kVp). For beams with effective energies ranging from 136 to 142 keV, this difference
Dpto. Fisiología Médica y Biofísica, University of Seville, Seville, Spain Instituto de Biomedicina de Sevilla, Seville, Spain c Medical Radiation Physics, Stockholm University, Karolinska Institutet, Stockholm, Sweden d Centro Nacional de Aceleradores (CNA), Universidad de Sevilla, Junta de Andalucía, Consejo Superior de Investigaciones Científicas (CSIC), Seville, Spain e Hospital Universitario Virgen Macarena, Servicio de Radioterapia, Seville, Spain f Hospital Universitario Virgen Macarena, Servicio de Medicina Nuclear, Seville, Spain ⇑ Presenting author. b
Purpose. In order to start accurate clinical trials based on treatments more aggressive than traditional margin approaches, a robust optimization algorithm has been developed for dose calculation full Monte Carlo-based. Specifically, the algorithm is presented here to manage uncertainties on dose painting from PET/CT image data. Material and Methods. CARMEN platform [1] was updated to allow heterogeneous dose prescription by means the recurrent both approaches. For the approach considered as true dose painting by number (tDPBN) where the restriction of dose to volumes makes no sense, it was necessary to develop a novel algorithm including an optimization method at the voxel level under Lineal Programming (LP) formulation [2]. For the approach based on the discretization of functional information into several clusterings (DPBN), instead of a recurrent equidistant isolevel, we implemented several algorithms able to reflect the diffuse and multifocal nature of the uptake regions. For this study, the affinity propagation proposed by Foster [3] in order to reduce random errors due to the PET images registration process. Full Monte Carlo simulations were performed for preoptimization and final dose calculation for taking into account the interactions of particles by means an explicit transport along the beam modifiers in the linac head. Axesse/Synergy linacs of Elekta were modellized with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code, a modified version of DOSXYZnr for calculate the specific beamlet dose contribution on each voxel. A grid calculation consisting on 256 256 voxels per slice was used from the interpolation of PET/CT images reconstructed by keeping a compromise with EARL (ResEARch4LifeÒ) accreditation requirements. Linear Programming formulation at voxel level allowed stablishing a tractable robustness of the uncertainties related to the heterogeneous dose prescription, imposing lower and upper-bound constraints to each voxel in accordance to the clustering volume to which they belong. For tDPBN, an inverse planning schema was previously developed [4]. For DPBN by clusterings approach, a specific direct aperture opti-