RADAR reference adult, pediatric, and pregnant female phantom series for internal and external dosimetry

Abstract

A new generation of reference computational phantoms, based on image-based models tied to the reference masses defined by the International Commission on Radiological Protection (ICRP) for dose calculations, is presented.

Methods: Anatomic models based on nonuniform rational b-spline modeling techniques were used to define reference male and female adults, 15-y-olds, 10-y-olds, 5-y-olds, 1-y-olds, newborns, and pregnant women at 3 stages of gestation, using the defined reference organ masses in ICRP publication 89. Absorbed fractions and specific absorbed fractions for internal emitters were derived using standard Monte Carlo radiation transport simulation codes.

Results: Differences were notable between many pairs of organs in specific absorbed fractions because of the improved realism of the models, with adjacent organs usually closer and sometimes touching. Final estimates of absorbed dose for radiopharmaceuticals, for example, were only slightly different overall, as many of the differences were small and most pronounced at low radiation energies. Some new important organs were defined (salivary glands, prostate, eyes, and esophagus), and the identity of a few gastrointestinal tract organs changed.

Conclusion: A new generation of reference models for standardized internal and external dose calculations has been defined. The models will be implemented in standardized software for internal dose calculations and be used to produce new standardized dose estimates for radiopharmaceuticals and other applications.

FIGURE 1

Exterior view of one of the Cristy/Eckerman 1987 phantoms (1).

FIGURE 2

Anterior views of Segars (15) NURBS models of adult male (A) and adult female (B).

FIGURE 3

Rendering of selected NURBS ICRP 89 phantoms: newborn female model (A), 5-y-old male model (B), 10-y-old female model (C), and 15-y-old male model (D).

FIGURE 4

Rendering of 3-dimensional organ and body surfaces for RPI pregnant female models: 3 mo (A), 6 mo (B), and 9 mo (C).

FIGURE 5

Sample SAF plots for ICRP 89 pediatric and adult models: male, photons stomach←liver (A), female, photons lungs←lungs (B), male, electrons kidneys←kidneys (C), and female, adrenals←kidneys (D).