Hybrid computational phantoms for medical dose rec

Authors: Wesley Bolch Choonsik Lee Michael Wayson Perry Johnson

Publish Date: 2009/12/29

Volume: 49, Issue: 2, Pages: 155-168

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Abstract

As outlined in NCRP Report No 160 of the US National Council on Radiation Protection and Measurements NCRP the average value of the effective dose to exposed individuals in the United States has increased by a factor of 17 over the time period 1982–2006 with the contribution of medical exposures correspondingly increasing by a factor of 57 At present medical contributors to effective dose include computed tomography 50 of total medical exposure nuclear medicine 25 interventional fluoroscopy 15 and conventional radiography and diagnostic fluoroscopy 10 An increased awareness of medical exposures has led to a gradual shift in the focus of radiation epidemiological studies from traditional occupational and environmental exposures to those focusing on cohorts of medical patients exposed to both diagnostic and therapeutic sources The assignment of organ doses to patients in either a retrospective or a prospective study has increasingly relied on the use of computational anatomic phantoms In this paper we review the various methods and approaches used to construct patient models to include anthropometric databases cadaver imaging prospective volunteer imaging studies and retrospective image reviews Phantom format types—stylized voxel and hybrid—as well as phantom morphometric categories—reference patientdependent and patientspecific—are next defined and discussed Specific emphasis is given to hybrid phantoms—those defined through the use of combinations of polygon mesh and nonuniform rational Bspline NURBS surfaces The concept of a patientdependent phantom is reviewed in which phantoms of non50th percentile heights and weights are designed from populationbased morphometric databases and provided as a larger library of phantoms for patient matching and lookup of refined values of organ dose coefficients and/or radionuclide S values We close with two brief examples of the use of hybrid phantoms in medical dose reconstruction—diagnostic nuclear medicine for pediatric subjects and interventional fluoroscopy for adult patients

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