TY - JOUR T1 - Internal dosimetry calculation from newborn hybrid computational phantoms having ICRP reference anatomy JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 135P LP - 135P VL - 48 IS - supplement 2 AU - Choonsik Lee AU - Daniel Lodwick AU - Wesley Bolch Y1 - 2007/05/01 UR - http://jnm.snmjournals.org/content/48/supplement_2/135P.1.abstract N2 - 458 Objectives: Stylized phantoms used for internal dosimetry calculation have been reported to be unrealistic compared to human anatomy. Although more realistic voxel phantoms have been developed from medical images, they also have limitations in describing anatomical details and representing average anatomy. This study was intended to develop newborn hybrid phantoms having reference anatomy of International Commission on Radiological Protection (ICRP), and to apply them to specific absorbed fractions (SAFs) calculation. Methods: To develop hybrid phantoms, mathematical equations of stylized phantoms were replaced with non-uniform rational B-splines(NURBS) and 485 computed tomography(CT) images were employed to obtain anatomical realism. Organ contours were segmented from CT images by using 3D-DOCTOR(TM) to generate polygon mesh, which was used for NURBS modeling where organ contours were manipulated by Rhinoceros(TM) to match reference organ mass within 1%. NURBS newborn phantom was voxelized and incorporated into EGSnrc, Monte Carlo transport code to calculate SAFs for photon and electron with the energy from 0.01 MeV to 4 MeV. Results: SAFs for 60 source and target organs were calculated and compared to those from ORNL newborn phantom and UF newborn voxel phantom. In comparison with ORNL phantom, major differences were attributed to unrealistic inter-organ distance in ORNL phantom. In comparison with UF voxel phantom, differences were caused by the individual-specific organ masses in UF phantom which were 3%-78% different from reference organ mass. Prominent advance in hybrid phantom is to provide more realistic alimentary SAFs compared to other two phantoms. Conclusions: The SAFs calculated in this study showed that hybrid phantoms can provide more realistic and standardized internal dosimetry calculation than stylized and voxel phantoms. The new hybrid approach to model human anatomy can be widely applied to dose evaluation in nuclear medicine where realistic and flexible computational phantoms are required. ER -