Paediatric Reference Computational Phantoms

The draft Paediatric Reference Computational Phantoms is now available for public consultation. We welcome comments from individuals and organisations. The draft document can be downloaded from the ICRP website. Comments must be submitted through the ICRP website no later than November 9, 2018.

Abstract

This report describes the development and intended use of a series of ten computational phantoms representing the reference male and female at newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old as defined in Publication 89. These phantoms have been formally adopted by the ICRP for use within ICRP Committee 2 in the development of age-dependent dose coefficients following the 2007 Recommendations. They are presented in this report in the very same voxelized structures and tissue ID numbers as given in Publication 110 for the adult reference computational phantoms. These paediatric phantoms have been used by Task Group 90 of ICRP Committee 2 in the development of age-dependent dose coefficients representing external exposures to contaminated air, water, and soil. They have also been used by Task Group 96 of ICRP Committee 2 in the development of age-dependent specific absorbed fractions for internally emitted photons, electrons, alpha particles, and neutrons, in a manner similar to the adult SAF (Specific Absorbed Fraction) values given in Publication 133. These age-dependent SAF values are currently being utilized by Task Group 96 in the preparation of age-dependent dose coefficients for radionuclide ingestion and inhalation as part of the forthcoming EIR (Environmental Intakes of Radionuclide) publication series which updates the dose coefficients of ICRP Publications 56, 67, 71, and 72. Chapter 1 summarises the main reasons for constructing these phantoms – voxel phantoms that comply with the reference anatomical characteristics of the non-adult reference individuals presented in Publication 89. Chapter 2 reviews the body size/shape and organ-specific specifications of the ICRP paediatric reference phantoms. Chapter 3 presents in detail the methods of their construction which includes 9 specific steps in their development: (1) selection of CT tomographic data, (2) segmentation of those CT images, (3) body contour and organ modelling via NURBS/PM surfaces, (4) adjustments of outer body contour to match total body mass, (5) adjustments of individual organ values to match reference masses, (6) subdivision of the skeletal tissues, (7) voxelization of the NURBS/PM surfaces, (8) voxel retagging for lymphatic nodes and skeletal muscle, and (9) further modifications to bring the series of paediatric phantoms into a structure identical to that original established for the adult phantoms of Publication 110. Chapter 4 follows with a description of the ICRP paediatric reference phantoms including their main characteristics, skeletal source/target regions, regional blood distribution, and phantom limitations. The report is supported by a series of annexes. Annex A provides details on tissue ID numbers, tissue media, mass densities, and organ locations by both coordinate position and voxel count. Annex B provides a complete list of the various age-dependent and gender-dependent tissue media, their phantom masses, and elemental compositions. Annexes C and D provide a listing of all source and target regions, respectively, needed for internal as well as external dosimetry applications. Annexes E and F provide depth distributions and organ pair distance distributions, respectively, in a manner similar to that provided in Publication 110 for the adult phantoms. Annex G provides cross-sectional images – sagittal, coronal, and transverse planes. Finally, Annex H gives a description of the electronic files available for download and use of each of the 10 paediatric reference computational phantoms.

Draft Document: Paediatric Reference Computational Phantoms


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