The UF/NCI family of hybrid computational phantoms representing the current US population of male and female children, adolescents, and adults—application to CT dosimetry

Abstract

Substantial increases in pediatric and adult obesity in the US have prompted a major revision to the current UF/NCI (University of Florida/National Cancer Institute) family of hybrid computational phantoms to more accurately reflect current trends in larger body morphometry. A decision was made to construct the new library in a gridded fashion by height/weight without further reference to age-dependent weight/height percentiles as these become quickly outdated. At each height/weight combination, circumferential parameters were defined and used for phantom construction. All morphometric data for the new library were taken from the CDC NHANES survey data over the time period 1999-2006, the most recent reported survey period. A subset of the phantom library was then used in a CT organ dose sensitivity study to examine the degree to which body morphometry influences the magnitude of organ doses for patients that are underweight to morbidly obese in body size. Using primary and secondary morphometric parameters, grids containing 100 adult male height/weight bins, 93 adult female height/weight bins, 85 pediatric male height/weight bins and 73 pediatric female height/weight bins were constructed. These grids served as the blueprints for construction of a comprehensive library of patient-dependent phantoms containing 351 computational phantoms. At a given phantom standing height, normalized CT organ doses were shown to linearly decrease with increasing phantom BMI for pediatric males, while curvilinear decreases in organ dose were shown with increasing phantom BMI for adult females. These results suggest that one very useful application of the phantom library would be the construction of a pre-computed dose library for CT imaging as needed for patient dose-tracking.

An exponential growth of computational phantom research in radiation protection, imaging, and radiotherapy: a review of the fifty-year history

“…In September 2008, ICRP established that its future reference phantoms for pediatric individuals would be based upon the UF series of hybrid phantoms. Recently, Geyer et al (2014) summarized their family phantoms and application to CT dose calculations at the Zurich workshop. Figure 21 shows the UF family phantoms developed using BREP methods (Bolch et al 2010).…”

Convolution-based estimation of organ dose in tube current modulated CT

“…Recent work includes the organ dose simulation on voxelized or hybrid computation phantoms. Several recent studies have demonstrated the feasibility of using a large library of computational phantoms and quantifying patient anatomical factors with a database of protocol-, patient-, and organ-specific CTDI vol -normalized-organ dose coefficients (Li et al 2011, Turner et al 2011, Geyer et al 2014, Sahbaee et al 2014, Tian et al 2014). …”

Estimation of Radiation Dose in CT Based on Projection Data

“…However, these approaches generally rely on pre-calculated organ dose and are limited to a small number of phantoms [12]. Recently, there has been a growing effort to combine Monte Carlo simulation and computational phantoms to simulate organ dose across a relatively large patient population [13][14][15]. Although very accurate, the Monte Carlo method is usually computationally expensive since it requires calculations of a large number of photons propagating in the object.…”