Comparison of neutron organ and effective dose coefficients for PIMAL stylized phantom in bent postures in standard irradiation geometries

Abstract

Neutron dose coefficients for standard irradiation geometries have been reported in International Commission on Radiological Protection (ICRP) Publication 116 for the ICRP Publication 110 adult reference phantoms. In the present work, organ and effective dose coefficients have been calculated for a receptor in both upright and articulated (bent) postures representing more realistic working postures exposed to a mono-energetic neutron radiation field. This work builds upon prior work by Dewji and co-workers comparing upright and bent postures for exposure to mono-energetic photon fields. Simulations were conducted using the Oak Ridge National Laboratory's articulated stylized adult phantom, "Phantom wIth Moving Arms and Legs" (PIMAL) software package, and the Monte Carlo N-Particle (MCNP) version 6.1.1 radiation transport code. Organ doses were compared for the upright and bent (45° and 90°) phantom postures for neutron energies ranging from 1 × 10 to 20 MeV for the ICRP Publication 116 external exposure geometries-antero-posterior (AP), postero-anterior (PA), and left and right lateral (LLAT, RLAT). Using both male and female phantoms, effective dose coefficients were computed using ICRP Publication 103 methodology. The resulting coefficients for articulated phantoms were compared to those of the upright phantom. Computed organ and effective dose coefficients are discussed as a function of neutron energy, phantom posture, and source irradiation geometry. For example, it is shown here that for the AP and PA irradiation geometries, the differences in the organ coefficients between the upright and bent posture become more pronounced with increasing bending angle. In the AP geometry, the brain dose coefficients are expectedly higher in the bent postures than in the upright posture, while all other organs have lower dose coefficients, with the thyroid showing the greatest difference. Overall, the effective dose estimated for the upright phantom is more conservative than that for the articulated phantom, which may have ramifications in the estimation or reconstruction of radiation doses.

Monte-Carlo based investigation of individual dosimetry in deep geological repository for high-level nuclear waste with consideration of realistic body postures

“…In general, the effective dose conversion coefficients obtained in the current study coincide with those reported by Bales et al (2018) with the same PIMAL phantom. However, compared to the results provided in (Bales et al, 2018) a much better agree ment with the dose conversion coefficients published by ICRP (ICRP, 2010) was obtained in the current study for neutron energy lager than 5 MeV.…”

“…7(a) (e) compare for the standard irradiation geometries AP, PA, LLAT, RLAT and ISO, the effective dose conver sion coefficients obtained by the PIMAL phantom in vertical upright posture with the respective coefficients provided by ICRP obtained by the ICRP/ICRU reference voxel phantom as given in the publication 116 (ICRP, 2010). Also included in the subfigures for the AP, PA, LLAT and RLAT geometries are the dose conversion coefficients reported by Bales et al (2018) with the same PIMAL phantom as in the current study. Noted that for the ISO irradiation geometry no data was available in the publication of Bales et al (2018).…”

“…Also included in the subfigures for the AP, PA, LLAT and RLAT geometries are the dose conversion coefficients reported by Bales et al (2018) with the same PIMAL phantom as in the current study. Noted that for the ISO irradiation geometry no data was available in the publication of Bales et al (2018). Finally, Fig.…”

“…To be more precisely speaking, the very term of effective dose can only be used specifically with the ICRP/ICRU voxel phantom. Consequently, in this study a dose quantity according to the definition of effective dose but with the PIMAL phantom instead of the ICRP/ICRU voxel phantom was calculated similarly to the investigations in(Hiller and Dewji, 2017;Bales et al, 2018).…”

Development of a novel program for conversion from tetrahedral‐mesh‐based phantoms to DICOM dataset for radiation treatment planning: TET2DICOM

“…Recently, several investigators have developed NURBS/polygonal mesh (PM)-based hybrid phantom that can address the limitations of the voxel phantom and be deformed in various postures. 12,[15][16][17][18] Based on this, the deformed hybrid phantom has been modeled with various ages and shapes. In addition, a program to convert the hybrid phantom to DICOM was developed for the purpose of clinical application.…”