Comparison between effective doses for voxel-based and stylized exposure models from photon and electron irradiation

Abstract

For the last two decades, the organ and tissue equivalent dose as well as effective dose conversion coefficients recommended by the International Commission on Radiological Protection (ICRP) have been determined with exposure models based on stylized MIRD5-type phantoms representing the human body with its radiosensitive organs and tissues according to the ICRP Reference Man released in Publication No. 23, on Monte Carlo codes sometimes simulating rather simplified radiation physics and on tissue compositions from different sources. Meanwhile the International Commission on Radiation Units and Measurements (ICRU) has published reference data for human tissue compositions in Publication No. 44, and the ICRP has released a new report on anatomical reference data in Publication No. 89. As a consequence many of the components of the traditional stylized exposure models used to determine the effective dose in the past have to be replaced: Monte Carlo codes, human phantoms and tissue compositions. This paper presents results of comprehensive investigations on the dosimetric consequences to be expected from the replacement of the traditional stylized exposure models by the voxel-based exposure models. Calculations have been performed with the EGS4 Monte Carlo code for external and internal exposures to photons and electrons with the stylized, gender-specific MIRD5-type phantoms ADAM and EVA on the one hand and with the recently developed tomographic or voxel-based phantoms MAX and FAX on the other hand for a variety of exposure conditions. Ratios of effective doses for the voxel-based and the stylized exposure models will be presented for external and internal exposures to photons and electrons as a function of the energy and the geometry of the radiation field. The data indicate that for the exposure conditions considered in these investigations the effective dose may change between +60% and -50% after the replacement of the traditional exposure models by the voxel-based exposure models.

Pediatric radiation dosimetry for positron‐emitting radionuclides using anthropomorphic phantoms

“…23,24,[41][42][43]53 However, significant differences between the dosimetric characteristics of stylized and voxel-based models for the same subject are often reported. [44][45][46][47] In the case of the newborn, the variations of the estimated self-absorbed S-values for positron-emitting radionuclides may range from −78% to 132% between stylized and voxel-based phantoms in representative organs. Since some biological tissues in children may have substantially different physical characteristics and tissue chemical compositions and present with significantly different radiosensitivity and bioavailability for various radiotracers at different ages, the evaluation of age-dependent absorbed dose using realistic anatomical anthropomorphic pediatric phantoms is commended.…”

“…However, significant differences have been reported between dosimetric results of stylized and voxel-based models of the same subject. [44][45][46][47] Therefore, the assessment of radiation dose for commonly used positron-emitting radionuclides in new generation anthropomorphic pediatric phantoms is highly desired.…”

Assessment of radiation dose in nuclear cardiovascular imaging using realistic computational models

“…40 For pediatric populations, the relative differences of the effective dose between University of Florida-National Cancer Institute (UF-NCI) phantoms and stylized phantoms may change between −24% and 33% for positron-emitting radiotracers. 35 Therefore, the assessment of organ absorbed dose and effective dose for commonly used nuclear cardiology radiotracers using new generation computational phantoms is desired.…”

Pulmonary embolism in pregnant patients: Assessing organ dose to pregnant phantom and its fetus during lung imaging

“…used the stylized pregnant phantoms in dose estimation with three layers of 1.5 cm thickness mimic various body mass indexes . Several studies have been conducted to show the systematic discrepancy between data obtained with stylized phantom and image‐based computational phantoms . ICRP recommendations also confirm that external and internal dosimetry calculations should be performed using image‐based computational phantoms replacing the use of various stylized models .…”