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Carter, L. M.*; Crawford, T. M.*; Sato, Tatsuhiko; Furuta, Takuya; Choi, C.*; Kim, C. H.*; Brown, J. L.*; Bolch, W. E.*; Zanzonico, P. B.*; Lewis, J. S.*
Journal of Nuclear Medicine, 60(12), p.1802 - 1811, 2019/12
Times Cited Count：22 Percentile：80.72(Radiology, Nuclear Medicine & Medical Imaging)Voxel human phantoms have been used for internal dose assessment. More anatomically accurate representation become possible for skins or layer tissues owing to recent developments of advanced polygonal mesh-type phantoms and thus internal dose assessment using those advanced phantoms are desired. However, the Monte Carlo transport calculation by implementing those phantoms require an advanced knowledge for the Monte Carlo transport codes and it is only limited to experts. We therefore developed a tool, PARaDIM, which enables users to conduct internal dose calculation with PHITS easily by themselves. With this tool, a user can select tetrahedral-mesh phantoms, set radionuclides in organs, and execute radiation transport calculation with PHITS. Several test cases of internal dosimetry calculations were presented and usefulness of this tool was demonstrated.
Yeom, Y. S.*; Han, M. C.*; Choi, C.*; Han, H.*; Shin, B.*; Furuta, Takuya; Kim, C. H.*
Health Physics, 116(5), p.664 - 676, 2019/05
Times Cited Count：7 Percentile：60.64(Environmental Sciences)Recently, Task Group 103 of the ICRP developed the mesh-type reference computational phantoms (MCRPs), which are planned for use in future ICRP dose coefficient calculation. Performance of major Monte Carlo particle transport codes (Geant4, MCNP6, and PHITS) were tested with MCRP. External and internal exposure of various particles and energies were calculated and the computational times and required memories were compared. Additionally calculation for voxel-mesh phantom was also conducted so that the influence of different mesh-representation in each code was studied. Memory usage of MRCP was as large as 10 GB with Geant4 and MCNP6 while it is much less with PHITS (1.2 GB). In addition, the computational time required for MRCP tends to increase compared to voxel-mesh phantoms with Geant4 and MCNP6 while it is equal or tends to decrease with PHITS.
Han, M. C.*; Yeom, Y. S.*; Lee, H. S.*; Shin, B.*; Kim, C. H.*; Furuta, Takuya
Physics in Medicine & Biology, 63(9), p.09NT02_1 - 09NT02_9, 2018/05
Times Cited Count：7 Percentile：38.85(Engineering, Biomedical)The multi-threading computation performances of the Geant4, MCNP6, and PHITS codes were evaluated using three tetrahedral-mesh phantoms with different complexity. Photon and neutron transport simulations were conducted and the initialization time, calculation time, and memory usage were measured as a function of the number of threads N used in the simulation. The initialization time significantly increases with the complexity of the phantom, but not much with the number of the threads. For the calculation time, Geant4 showed good parallelization efficiency with multi-thread computation (30 times speed-up factor for N = 40) adopting the private tallies while saturation of the speed-up factor were observed in MCNP6 and PHITS (10 and a few times for N = 40) due to the time delay for the sharing tallies. On the other hand, Geant4 requires larger memory specification and the memory usage rapidly increases with the number of threads compared to MCNP6 or PHITS. It is notable that when compared to the other codes, the memory usage of PHITS is much smaller, regardless of both the complexity of the phantom and the number of the threads.
Furuta, Takuya; Sato, Kaoru; Takahashi, Fumiaki
no journal, ,
Voxel-based computational human phantoms have been used for radiation dose assessment with Monte Carlo radiation transport simulation codes. However, development of polygon-based computation humans becomes popular due to advantages on description of thin layer tissues and small organs. International Commission on Radiological Protection (ICRP) also announced to adopt polygon human phantoms as the reference phantoms. We therefore introduced a function to treat tetrahedral-mesh geometry, a type of polygon geometry, into Particle and Heavy Ion Transport code Systems (PHITS). Along this implementation, we also developed an efficient transport algorithm with tetrahedral-mesh geometry, which allows to reduce the computational time to 1/4 of the voxel-mesh calculation using the same precision computational human phantom. We also started a development of new polygon-based human phantoms based on Japanese voxel phantoms. The complete version will be published hopefully next year.
Furuta, Takuya
no journal, ,
Recently polygon phantoms with tetrahedral-mesh became treatable in PHITS by implementation of a new function. Using this function, radiation transport simulation of external radiation exposure of the new ICRP mesh-type reference computational phantoms becomes possible. The function was introduced together with an original algorithm to limit number of elements and surfaces in search during the transport calculation to reduce the computational cost. Owing to this algorithm, efficient transport calculation in tetrahedral-mesh geometries was realized as good as in voxel-mesh geometries with the same number of meshes. The tetrahedral-mesh can represent complex structures such as human phantoms with a much smaller number of meshes compared to the voxel representation and thus the computational speeds of radiation transport simulation using human phantoms can be faster with tetrahedral-mesh representation. The performance of PHITS was demonstrated by a comparison of the computational time between the voxel and tetrahedral-mesh for radiation transport calculations in water and human phantoms. Benchmark studies using the ICRP mesh-type reference computational phantoms in comparison with other Monte Carlo codes such as MCNP and Geant4 were also performed.
