chapter  8
22 Pages

The University of Florida Pediatric Phantom Series

ByChoonsik Lee, Daniel L. Lodwick, Deanna Hasenauer Pafundi, Scott R. Whalen, Jonathan L. Williams, Wesley E. Bolch

This chapter reviews the development of a series of pediatric whole-body phantoms based on non-uniform rational B-spline (NURBS) surfaces as constructed at the Advanced Laboratory for Radiation Dosimetry Studies (ALRADS), University of FL, Gainesville, FL. We introduce the development procedure mainly for the newborn phantom, as that was the

rst hybrid phantom in which NURBS technology was incorporated. Other older phantoms ranging from 1 to 15 years old were extensions of this newborn phantom. We further subdivided the phantom series into two groups-Group A and Group B. Group A is composed of male and female phantoms of the newborn, 1 year old, 5 years old, 10 years old, and 15 years old, where phantom stature, total weight, and individual organ masses are targeted to within 1% of ICRP Publication 89 reference values. While the newborn phantoms were constructed from whole-body CT scans of a newborn cadaver, the remaining phantoms of Group A were constructed from segmented head and chest-abdomen-pelvis CT images from live pediatric patients all of normal anatomy. Group B phantoms are constructed as upwardly and downwardly scaled versions of the Group A phantoms, thus providing a phantom at each 1 year interval, from newborn to 15 years old. The intent of the University of Florida (UF) pediatric series is to provide a reference library of phantoms for matching to individual patients in organ dose assessment in radiography, uoroscopy, CT imaging, and radiotherapy. In traditional medical dose reconstruction, 50th percentile reference phantoms are assigned to individual patients based upon their age. In the UF approach, phantoms are assigned to individual patients, not based on age, but on trunk height, thus reducing residual uncertainties in organ volumes from as high as 50% to as low at 15%. Next, leg lengths are adjusted to match patient statue, and nally, the outer body contour of the phantom is adjusted to match as closely as possible the patient’s body distribution of subcutaneous fat and/or muscle. The overall approach thus yields a highly patient-speci c phantom for dose assessment than afforded by existing applications. Finally, we discuss in this chapter our efforts to provide, through tissue sampling and microCT image analysis, detailed and agespeci c skeletal computational phantoms for each phantom of the UF series.