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RISS 인기검색어
- 검색키워드
- 저자 : Zankl, Maria (검색결과 5 건)
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- 유료
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New small-intestine modeling method for surface-based computational human phantoms
Yeom, Yeon Soo,Kim, Han Sung,Nguyen, Thang Tat,Choi, Chansoo,Han, Min Cheol,Kim, Chan Hyeong,Lee, Jai Ki,Zankl, Maria,Petoussi-Henss, Nina,Bolch, Wesley E,Lee, Choonsik,Chung, Beom Sun IOP 2016 Journal of radiological protection Vol.36 No.2
<P>When converting voxel phantoms to a surface format, the small intestine (SI), which is usually not accurately represented in a voxel phantom due to its complex and irregular shape on one hand and the limited voxel resolutions on the other, cannot be directly converted to a high-quality surface model. Currently, stylized pipe models are used instead, but they are strongly influenced by developer’s subjectivity, resulting in unacceptable geometric and dosimetric inconsistencies. In this paper, we propose a new method for the construction of SI models based on the Monte Carlo approach. In the present study, the proposed method was tested by constructing the SI model for the polygon-mesh version of the ICRP reference male phantom currently under development. We believe that the new SI model is anatomically more realistic than the stylized SI models. Furthermore, our simulation results show that the new SI model, for both external and internal photon exposures, leads to dose values that are more similar to those of the original ICRP male voxel phantom than does the previously constructed stylized SI model.</P>
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Development of skeletal system for mesh-type ICRP reference adult phantoms
Yeom, Yeon Soo,Wang, Zhao Jun,Nguyen, Thang Tat,Kim, Han Sung,Choi, Chansoo,Han, Min Cheol,Kim, Chan Hyeong,Lee, Jai Ki,Chung, Beom Sun,Zankl, Maria,Petoussi-Henss, Nina,Bolch, Wesley E,Lee, Choonsik IOP 2016 Physics in medicine & biology Vol.61 No.19
<P>The reference adult computational phantoms of the international commission on radiological protection (ICRP) described in <I>Publication</I> 110 are voxel-type computational phantoms based on whole-body computed tomography (CT) images of adult male and female patients. The voxel resolutions of these phantoms are in the order of a few millimeters and smaller tissues such as the eye lens, the skin, and the walls of some organs cannot be properly defined in the phantoms, resulting in limitations in dose coefficient calculations for weakly penetrating radiations. In order to address the limitations of the ICRP-110 phantoms, an ICRP Task Group has been recently formulated and the voxel phantoms are now being converted to a high-quality mesh format. As a part of the conversion project, in the present study, the skeleton models, one of the most important and complex organs of the body, were constructed. The constructed skeleton models were then tested by calculating red bone marrow (RBM) and endosteum dose coefficients (DCs) for broad parallel beams of photons and electrons and comparing the calculated values with those of the original ICRP-110 phantoms. The results show that for the photon exposures, there is a generally good agreement in the DCs between the mesh-type phantoms and the original voxel-type ICRP-110 phantoms; that is, the dose discrepancies were less than 7% in all cases except for the 0.03 MeV cases, for which the maximum difference was 14%. On the other hand, for the electron exposures (⩽4 MeV), the DCs of the mesh-type phantoms deviate from those of the ICRP-110 phantoms by up to ~1600 times at 0.03 MeV, which is indeed due to the improvement of the skeletal anatomy of the developed skeleton mesh models.</P>
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Lee, Hanjin,Yeom, Yeon Soo,Nguyen, Thang Tat,Choi, Chansoo,Han, Haegin,Shin, Bangho,Zhang, Xujia,Kim, Chan Hyeong,Chung, Beom Sun,Zankl, Maria IOP 2019 Physics in medicine & biology Vol.64 No.4
<P>Recently, the Task Group 103 of the International Commission on Radiological Protection (ICRP) has developed new mesh-type reference computational phantoms (MRCPs) for adult male and female. When compared to the current voxel-type reference computational phantoms in ICRP Publication 110, the MRCPs have several advantages, including deformability which makes it possible to create phantoms in different body sizes or postures. In the present study, the MRCPs were deformed to produce a set of percentile-specific phantoms representing the 10th, 50th and 90th percentiles of standing height and body weight in Caucasian population. For this, anthropometric parameters for the percentile-specific phantoms were first derived from the anthropometric software and survey data. Then, the MRCPs were modified to match the derived anthropometric parameters. For this, first, the MRCPs were scaled in the axial direction to match the head height, torso length, and leg length. Then, the head, torso, and legs were scaled in the transversal directions to match the lean body mass for the percentile-specific phantoms. Finally, the scaled phantoms were manually adjusted to match the body weight and the remaining anthropometric parameters (upper arm, waist, buttock, thigh, and calf circumferences and sagittal abdominal diameter). The constructed percentile-specific phantoms and the MRCPs were implemented into the Geant4 Monte Carlo code to calculate organ doses for a cesium-137 contaminated floor. The results showed that organ doses of the 50th percentile (both standing height and body weight) phantoms are very close to those of the MRCPs. There were noticeable differences in organ doses, however, for the 10th and 90th percentile phantoms when compared with those of the MRCPs. The results of the present study confirm the general intuition that a small person receives higher doses than a large person when exposed to a static radiation field, and organs closer to the source receive higher doses.</P>
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Kim, Han Sung,Yeom, Yeon Soo,Nguyen, Thang Tat,Choi, Chansoo,Han, Min Cheol,Lee, Jai Ki,Kim, Chan Hyeong,Zankl, Maria,Petoussi-Henss, Nina,Bolch, Wesley E,Lee, Choonsik,Qiu, Rui,Eckerman, Keith,Chung, Institute of Physics in association with the Ameri 2017 Physics in medicine & biology Vol. No.
<P>It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP <I>Publications 100</I> and <I>66</I> were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP <I>Publications 100</I> and <I>66</I>. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP <I>Publications</I>.</P>
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