Conversion Coefficients for Proton Beams using Standing and Sitting Male Hybrid Computational Phantom Calculated in Idealized Irradiation Geometries.
The aim of this study was the calculation of conversion coefficients for absorbed doses per fluence (DT/Φ) using the sitting and standing male hybrid phantom (UFH/NCI) exposure to monoenergetic protons with energy ranging from 2 MeV to 10 GeV. Sex-averaged effective dose per fluence (E/Φ) using the results of DT/Φ for the male and female hybrid phantom in standing and sitting postures were also calculated. Results of E/Φ of UFH/NCI standing phantom were also compared with tabulated effective dose conversion coefficients provided in ICRP publication 116. To develop an exposure scenario implementing the male UFH/NCI phantom in sitting and standing postures was used the radiation transport code MCNPX. Whole-body irradiations were performed using the recommended irradiation geometries by ICRP publication 116 antero-posterior (AP), postero-anterior (PA), right and left lateral, rotational (ROT) and isotropic (ISO). In most organs, the conversion coefficients DT/Φ were similar for both postures. However, relative differences were significant for organs located in the lower abdominal region, such as prostate, testes and urinary bladder, especially in the AP geometry. Results of effective dose conversion coefficients were 18% higher in the standing posture of the UFH/NCI phantom, especially below 100 MeV in AP and PA. In lateral geometry, the conversion coefficients values below 20 MeV were 16% higher in the sitting posture. In ROT geometry, the differences were below 10%, for almost all energies. In ISO geometry, the differences in E/Φ were negligible. The results of E/Φ of UFH/NCI phantom were in general below the results of the conversion coefficients provided in ICRP publication 116.
Departamento de Física, Universidade Federal de Sergipe; Campus Prof. José Aloísio de Campos, 49.100-000, São Cristóvão - SE, Brazil.
M C
MC
Alves
Instituto de Física, Universidade Federal de Uberlândia (INFIS/UFU), Caixa Postal 593, 38400-902 Uberlândia, MG, Brazil.
W S
WS
Santos
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, MD 20852, USA.
C
C
Lee
Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611-8300, USA.
W E
WE
Bolch
Dosimetry Division, Instituto de Radioproteção e Dosimetria, Rio de Janeiro, RJ 22783-127, Brazil.
J G
JG
Hunt
Departamento de Física, Universidade Federal de Sergipe; Campus Prof. José Aloísio de Campos, 49.100-000, São Cristóvão - SE, Brazil.
A B Carvalho
ABC
Júnior
D005260:Female; D006801:Humans; D008297:Male; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy; D019047:Phantoms, Imaging; D011187:Posture; D011522:Protons; D011829:Radiation Dosage; D011835:Radiation Protection; D014916:Whole-Body Irradiation
D011522:Protons
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