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Sato, Kaoru; Furuta, Takuya; Satoh, Daiki; Tsuda, Shuichi
PLOS ONE (Internet), 19(10), p.e0309753_1 - e0309753_26, 2024/10
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)The authors previously developed the adult male (JM-103) and female (JF-103) voxel phantoms with standard Japanese body sizes for dose assessment of radiation accidents and medical exposures. However, JM-103 and JF-103 were not applicable to dose assessment considering posture at the time of exposure due to limitations in description format and resolution. In this study, we developed the polygon mesh-type adult Japanese phantoms (male: JPM, female: JPF) based on JM-103 and JF-103. The detailed models of skin and lens with radiosensitive regions less than 1 mm thick were incorporated into JPM and JPF. The effective doses, and skin and lens (entire and radiosensitive regions) doses were calculated for external irradiation with photons or electrons in anterior-posterior geometry. It was confirmed that dose analysis results by JPM and JPF were consistent with the previous reports. In the future, we will develop a detailed dose assessment method for individuals, taking into account their postures at the time of exposure, by applying the posture deformation technique currently under development to the JPM and JPF.
Furuta, Takuya
ANS RPSD 2018; 20th Topical Meeting of the Radiation Protection and Shielding Division of ANS (CD-ROM), 5 Pages, 2018/08
Recently we introduced a function in PHITS to treat tetrahedral-mesh geometry. Tetrahedral-mesh geometry is a structure composed of combination of tetrahedrons and able to construct complex objects. Tetrahedral-mesh objects can be obtained by converting polygon data using mesh generation software such as TetGen. We also implemented a function in PHITS to export tally results into the format of the three-dimensional visualization software ParaView. TetGen is able to convert the polygon data into ParaView format. Together with these tools, three-dimensional analysis can be realized for PHITS simulation using a polygon objects.
Furuta, Takuya
no journal, ,
It was difficult to construct complex three-dimensional (3D) geometries with original version of PHITS because 3D geometries in PHITS are defined by combinations of objects enclosed by simple surfaces planes, spheres, cylinders and so on. Useful software to construct 3D geometries interactively exists on the market and there are many requests from users to use such softwares in PHITS. We thus introduce a function to treat tetrahedral-mesh geometries, which is a type of polygon-mesh geometries, in PHITS. Being one of the simplest, the tetrahedral-mesh geometry is sufficiently flexible to construct complex geometries. Designing with CAD software is also possible with format conversions. In addition, we have introduced a function to create decomposition maps of tetrahedral-mesh objects at the initial process so that the computational time for transport process can be reduced. Owing to this function, transport calculation in tetrahedral-mesh geometry can be as fast as that for the geometry in voxel-mesh with the same number of meshes.
Furuta, Takuya
no journal, ,
It was difficult to construct complex three-dimensional (3D) geometries with original version of PHITS because 3D geometries in PHITS are defined by combinations of objects enclosed by simple surfaces planes, spheres, cylinders and so on. There are many requests from users to have a function which enables to import general polygon geometries into PHITS. We thus introduce a function to treat tetrahedral-mesh geometries, which is a type of polygon-mesh geometries, in PHITS. Being one of the simplest, the tetrahedral-mesh geometry is sufficiently flexible to construct complex geometries. It is also compatible with other polygon-mesh geometries by format conversions. In addition, we have developed an algorithm to reduce computational time required by the transport process in tetrahedral geometries. Owing to this algorithm, transport calculation in tetrahedral-mesh geometry can be as fast as that for the geometry in voxel-mesh with the same number of meshes.
Sato, Kaoru; Furuta, Takuya; Takahashi, Fumiaki
no journal, ,
We previously constructed average adult Japanese voxel phantoms (male: JM-103, female: JF-103) and others with various body sizes for application to dose assessment against persons with Japanese physiques. Generally, voxel phantom is not practical tool for dose assessment under various posture conditions, because of long construction term and difficulty of organ deformation. Thus, we are now constructing adult Japanese polygon male (JPM) and female (JPF) phantoms by modifying JM-103 and JF-103. In construction of JPM and JPF, the following processing were performed: (1) extraction of organ surface from JM-103 and JF-103, (2) smoothing organ surface, (3) adjustment of mass, shape and location, (4) multilayering of constructed polygon. Masses of most organs in JPM or JPF agreed with adult Japanese averages within 5%. In future, we will develop the limb operation technique for JPM and JPF. JPM and JPF with the new technique will be used for dose assessment against persons with various postures.
Sato, Kaoru; Furuta, Takuya; Takahashi, Fumiaki
no journal, ,
We are now developing adult Japanese polygon human models (male: JPM and female: JPF) for the purposes of dose assessment of Japanese. At the 2nd joint annual research meeting of JHPS and JRSM, overviews of development of these human models were presented. Thereafter, we performed the improving of the posture change functions and averaging of organ masses and body sizes. In this presentation, we will introduce and explain about the characteristics of posture change functions and physiques of JPM and JPF. In addition, we will show test calculation results of organ doses under various postures.
Nishiyama, Nariaki*; Kawamura, Makoto; Umeda, Koji*; Goto, Akira; Niwa, Masakazu
no journal, ,
The topography of the volcanic mountain body is thought to reflect the actual distribution range of the dike. Based on this idea, we examined the modeling of the dike distribution and the evaluation of the central conduit stability focused on the shape of the contour lines. In this study, we drew the line with the maximum distance (long axis) in the contour distribution of each elevation and aggregated the orientation data, in addition to the data obtained from the analysis of Nishiyama et al. (2021). Moreover, we calculated the topographic parameter of each volcano, using the area data of the area enclosed by the contour lines (contour polygons). As a result, we found that the orientation of the long axis of the contour polygons of volcanic bodies shows the orientation trend in each volcano. The orientation of the line connecting the centroid of many volcanoes is consistent with that of the line connecting the centroid, which is roughly consistent with the direction of sigma 1 around the volcanoes. In general, dikes are characterized by extension in the direction of the maximum compression axis, and our topographic analysis results are consistent with this. As for the topographic parameters of each volcano using the area of contour polygons, the result suggests that it is possible to distinguish between volcanoes classified as central conduit stable and unstable by Takahashi (1994). Therefore, the topographic analysis is expected to be used to evaluate the stability of central conduit even for volcanoes whose activity history is not yet known. In the future, we will develop an evaluation method based on the above topographic features, and establish a method for evaluating the central conduit stability and modeling the distribution of dikes by topographic analysis.
Sato, Kaoru; Furuta, Takuya; Satoh, Daiki; Tsuda, Shuichi
no journal, ,
The authors are developing polygon mesh-type male (JPM) and female (JPF) phantoms of standard adult Japanese for the purpose of dose assessment taking into account the physical characteristics of adult Japanese. The stem cell regions were newly defined into JPM and JPF by image processing. For membranous organs such as the alimentary tracts and skin, the stem cell region was defined after constructing a layered structure to match the thickness given by ICRP. In addition, the detailed eyeball model adopted by ICRP was modified to have the average masses of the eyeball and lens of adult Japanese, and then introduced into JPM and JPF to enable the dose assessment for the stem cell region of the lens. Therefore, these are expected to be used in radiation exposure dose evaluation and radiation protection research in various fields, and will be made available for free on the GitHub web from October 24, 2024. In this presentation, we will report outline of the improvements and the release of JPM and JPF.
Sato, Kaoru; Furuta, Takuya
no journal, ,
In retrospective evaluation of exposure doses and risks, it is necessary to consider the individual differences in physiques and organ geometries in addition to exposure conditions. The presenters are now developing deformation functions of the physiques and organ shapes of the adult Japanese male polygon phantom (JPM) for purposes of the retrospective evaluation for individuals. The newly developed deformation functions are as follows: (1) dividing organs of JPM into "Units" composed of several organs based on anatomical information, (2) deforming each "Unit" by using Lattice method, (3) creating "Joint model" by combining the deformed "Units", and (4) reproducing the continuous shape changes of the organs by applying Morph method to "Joint models". The above process made it possible to deform the JPM without generating polygon intersections. The deformed JPM was applicable to the tetrahedralization and radiation transport simulation.
