Speaker
Description
The NJOY nuclear data processing system is widely used for pointwise and multigroup neutronic and photonic cross sections production from Evaluated Nuclear Data Files (ENDF). Current restriction to neutral particles-induced evaluations limits the scope of the system's mission to applications related to fission and fusion reactor design, licensing and safety analysis, stockpile stewardship modelling, criticality safety benchmarking, radiation shielding and nuclear waste management [1].
This paper proposes an extension and demonstration of the system capabilities for electron and positron-inducted evaluations in a radiation oncology context. We are proposing the implementation [2] and the validation of a new ELECTR module in NJOY with the production of 80-, 174- and 364-group ENDF/B-VIII.0 [3] libraries $-$ containing multigroup electroatomic cross sections, relaxation cascade production, anisotropic Legendre components of within-group elastic and group-to-group inelastic scattering matrices, radiative and collisional stopping powers, multigroup momentum transfer coefficients, energy and charge deposition cross sections, covering the [100 eV, 20 MeV] medical range for elements $Z=1$ (hydrogen) to $Z=100$ (fermium). Total, large angle elastic ($e,e$), catastrophic inelastic scattering ($e,2e$) and bremsstrahlung ($e,\gamma e$) cross sections feed the Boltzmann operators, while excitations are labelled soft, handled by the stopping powers and feed the 1st-order Fokker-Planck operator [4, 5]. Highly forward-peaked elastic scattering Legendre expansion is bypassed by the extended transport δ correction [6].
A first implementation of the ELECTR module, based on the CEPXS feed functions [7], was made. Our strategy is i) to replace the CEPXS feed functions with those described in the ENDF-102 specification report [8, 9]; and ii) to use EPICS-2017 data [10]. The final version of the ELECTR module with its validation will be presented at the meeting. The upgraded MATXSR post-processing module in NJOY formats each library in a single stand-alone multigroup dataset that can be accessed by a variety of legacy discrete ordinates and lattice codes including DRAGON-5 [11]. The produced MATXS file is then recovered by the DRAGON-5 Boltzmann-Fokker-Planck (BFP) discrete ordinate solver [12, 13], where a high-order diamond differencing (HODD) scheme is used for spatial discretization, with a $P_{l\geq 8}$ Legendre expansion for scattering anisotropy and $S_{n\geq 42}$ angular quadrature. Results are compared with the GEANT-4 Monte Carlo (MC) code [14, 15].
Electron beam dose distributions and charge depositions are compared for homogeneous tissue phantoms (water, cortical bone, male soft tissue, mean adipose, lung parenchyma, blood erythrocytes and skeletal muscle), homogeneous slab materials ($_{4}$Be, $_{6}$C, $_{13}$Al, $_{26}$Fe, $_{29}$Cu, $_{32}$Ge, $_{47}$Ag, $_{79}$Au, $_{82}$Pb and $_{92}$U), and an upgraded Ahnesjo's tissues stack benchmark [16]. Ionization, excitation and bremsstrahlung reaction rates obtained by DRAGON-5 are compared to GEANT-4 corresponding tallies. Electron contamination, bremsstrahlung spectrums, angular distributions and yields are produced and compared in a simplified medical LINAC head benchmark. An optimization of an Intraoperative Electron Radiation Therapy (IOERT) treatment planning [17] is demonstrated using the same NJOY-DRAGON chain. All computational schemes are uncoupled, based on the latest EEDL- and EADL (Rev.1)-2017 data [18, 19] and limited to semi-infinite slabs. Preliminary results, based on CEPXS feed functions, show that, on average, in $93.6\%$ of voxels, discrepancies from MC calculations are lower than the $2\%$ AAPM (American Association of Physicists in Medicine) Task Group tolerance criteria (Fig.1).
The feasibility of a deterministic Boltzmann-Fokker-Planck solver for electron beams treatment planning is demonstrated. We therefore anticipate an important role of the new module in systematic quality assurance for particle transport applications supporting nuclear medicine, brachytherapy, external radiotherapy and radiosurgery.
References
[1] R. MacFarlane, A. Kahler, Methods for processing ENDF/B-VII with NJOY, Nuclear Data Sheets 111 (12) (2010) 2739–2890.
[2] A. Hébert, A. Naceur, Implementation of the ELECTR in NJOY. 15th Int. Conf. on Nuclear Data for Science and Technology, Sacramento,
CA, July 24 – 29, 2022.
[3] D. A. Brown, et al., ENDF/B-VIII. 0: The 8th major release of the nuclear reaction data library with CIELO-project cross sections, new
standards and thermal scattering data, Nuclear Data Sheets 148 (2018) 1–142.
[4] J. Morel, Fokker-Planck calculations using standard discrete ordinates transport codes, Nuclear Science and Eng. 79 (4) (1981) 340–356.
[5] C. Leakeas, A Generalized Fokker-Planck Theory for Electron Transport Problems, PhD dissertation, The University of Michigan (1999).
[6] J. Morel, On the validity of the extended transport cross-section correction for low-energy electron transport, Nuclear Science and Engineering
71 (1) (1979) 64–71.
[7] L. Lorence, J. Morel, G. Valdez, Physics guide to CEPXS: A multigroup coupled electron-photon cross section generating code, Tech. rep., Sandia National Laboratory, SAND89-1685 (1989).
[8] V. McLane, ENDF-102 data formats and procedures for the evaluated nuclear data file ENDF-6, Tech. rep., Brookhaven National Lab. BNL-NCS–44945-01/04-REV. (2001)
[9] A. Tikov, M. Herman, D. Brown, ENDF-6 Formats Manual: Data Formats and Procedures for the Evaluated Nuclear Data Files ENDF/B-VI,
ENDF/B-VII and ENDF/B-VIII, Tech. rep., Brookhaven National Lab, CSEWG, BNL-203218-2018-INRE, Rev.215 (2018).
[10] D. Cullen, EPICS-2017: April 2019 Status Report, Tech. rep., Nuclear Data Services, IAEA-NDS-228 (2019).
[11] G. Marleau, A. Hébert, R. Roy, A User Guide for DRAGON Version 5, Institut de génie nucléaire, Département de génie physique, École
Polytechnique de Montréal. Montréal, QC, Canada, Tech. Rep. IGE-335.
[12] A. Hébert, C. Bienvenue, High-order diamond differencing schemes for the Boltzmann Fokker-Planck equation in 1D and 2D Cartesian
geometries. Submitted to Ann. Nuclear Energy.
[13] C. Bienvenue, A. Hébert, High-Order Diamond Differencing Schemes for the Boltzmann Fokker-Planck Equation in 3D Cartesian Geometries.
PHYSOR 2022 – Int. Conf. on Physics of Reactors 2022, May 15 – 20, Pittsburgh, PA, 2022.
[14] S. Agostinelli, et al., GEANT4—a simulation toolkit, Nuclear instruments and methods in physics research section A: Accelerators, Spectrometers,
Detectors and Associated Equipment 506 (3) (2003) 250–303.
[15] J. Allison, K. Amako, J. Apostolakis, P. Arce, M. Asai, T. Aso, E. Bagli, A. Bagulya, S. Banerjee, G. Barrand, et al., Recent developments in
Geant4, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
835 (2016) 186–225.
[16] A. Ahnesjo, M. M. Aspradakis, Dose calculations for external photon beams in radiotherapy, Physics in Medicine & Biology 44 (11) (1999)
R99.
[17] P. Guerra, J. M. Ud´ıas, E. Herranz, J. A. Santos-Miranda, J. L. Herraiz, M. F. Valdivieso, R. Rodrıguez, J. A. Calama, J. Pascau, F. A. Calvo,
et al., Feasibility assessment of the interactive use of a Monte Carlo algorithm in treatment planning for intraoperative electron radiation
therapy, Physics in Medicine & Biology 59 (23) (2014) 7159.
[18] D. Cullen, A Survey of Electron Cross Section Data for use in EPICS2017, Tech. rep., Nuclear Data Services, IAEA-NDS-226 (December
2017) (2017).
[19] D. Cullen, A Survey of Atomic Binding Energies for use in EPICS2017, Tech. rep., Nuclear Data Services, IAEA-NDS-224 (Rev.1, April
2018) (2018).