Effects of body habitus on internal radiation dose calculations using the 5-year-old anthropomorphic male models.

This study aims to evaluate the influence of body habitus on internal dosimetry and to quantify the uncertainties in dose estimation correlated with the use of fixed reference models. The 5-year-old IT'IS male phantom was modified to match target anthropometric parameters, including body weight, body height and sitting height/stature ratio (SSR), determined from reference databases, thus enabling the creation of 125 5-year-old habitus-dependent male phantoms with 10th, 25th, 50th, 75th and 90th percentile body morphometries. We evaluated the absorbed fractions and the mean absorbed dose to the target region per unit cumulative activity in the source region (S-values) of F-18 in 46 source regions for the generated 125 anthropomorphic 5-year-old hybrid male phantoms using the Monte Carlo N-Particle eXtended general purpose Monte Carlo transport code and calculated the absorbed dose and effective dose of five (18)F-labelled radiotracers for children of various habitus. For most organs, the S-value of F-18 presents stronger statistical correlations with body weight, standing height and sitting height than BMI and SSR. The self-absorbed fraction and self-absorbed S-values of F-18 and the absorbed dose and effective dose of (18)F-labelled radiotracers present with the strongest statistical correlations with body weight. For (18)F-Amino acids, (18)F-Brain receptor substances, (18)F-FDG, (18)F-L-DOPA and (18)F-FBPA, the mean absolute effective dose differences between phantoms of dif...

Source: Physics in Medicine and Biology - July 13, 2017 Category: Physics Authors: Xie T, Kuster N, Zaidi H Tags: Phys Med Biol Source Type: research