TY - JOUR T1 - Differences between four voxel-based dosimetry methods for 90Y microsphere therapy JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1277 LP - 1277 VL - 56 IS - supplement 3 AU - Justin Mikell AU - Armeen Mahvash AU - Wendy Siman AU - Firas Mourtada AU - Srinivas Kappadath Y1 - 2015/05/01 UR - http://jnm.snmjournals.org/content/56/supplement_3/1277.abstract N2 - 1277 Objectives In this study, we assessed differences between four different voxel-based dosimetry methods (VBDM) for tumor, liver, and lung doses following 90Y microsphere therapy (YMT) based on 90Y bremsstrahlung SPECT/CT. Simulations were used to investigate VBDM accuracy. Sensitivity of liver and lung dose estimates to organ segmentation was assessed.Methods VBDM investigated were Monte Carlo (MC), soft-tissue kernel (SK), soft-tissue kernel with density correction (SKD), and local deposition (LD). A total of 17 YMT cases were analyzed. Mean absorbed doses were calculated for tumor, normal liver (NL), and right lung (RL). Simulations with various SPECT spatial resolutions (FHWM) and lung shunt fractions (LS) were performed to estimate the accuracy of VBDMs around the liver-lung interface. Sensitivity of absorbed dose to organ segmentation was assessed from patient data by excluding volume near the liver-lung interface.Results For tumor mean absorbed doses, SKD was within 2% of MC, and all other VBDM were within 5%; similar results were found for NL. LD and SKD overestimated the RL mean absorbed dose compared to MC on average by 15% and 21%, respectively; SK underestimated the RL absorbed dose on average by -60%. Simulations (20 mm FWHM, 20% LS) showed that SKD, LD, and MC were within 10% of the true value deep (>39 mm) in lung; SK significantly underestimated the absorbed dose deep in lung by ~-70%. LD, SK, SKD, and MC were within 10% of true values deep (>12 mm) in the liver. Excluding 1, 2, and 3 cm of RL near the liver-lung interface changed the resulting RL mean absorbed dose by -21.8%, -38.0%, and -48.4%, respectively. An average change of -7% in the NL absorbed dose was seen when excluding 3 cm near the interface.Conclusions SKD, SK, and LD are equivalent to MC for liver tumors and NL. SK underestimates RL absorbed doses relative to MC whereas LD and SKD overestimate. RL mean absorbed doses are strongly influenced by the liver-lung interface region.Research Support NIH/NCI R01CA138986 ER -