Lung shunt fraction calculation using 99mTc-MAA SPECT/CT imaging for 90Y microsphere selective internal radiation therapy of liver tumors

Abstract Background 99m Tc-macroaggregated albumin ( Tc-MAA) scintigraphy is utilized in treatment planning for Yttrium-90 90 Y) Selective Internal Radiation Therapy (SIRT) of liver tumors to evaluate hepatopulmonary shunting by calculating the lung shunt fraction (LSF). The purpose this study was if LSF calculation using SPECT/CT instead planar gamma camera imaging more accurate and can potentially lead effective hepatic lesions while avoiding excessive pulmonary irradiation. Results obtained two different methodologies 85 cases from consecutive patients intended receive Y SIRT. first method based on anterior posterior views with geometric mean regions interest lungs. second segmentation lungs images thorax abdomen. differences versus derived values along estimated absorbed dose (LMD) were evaluated. higher 81/85 cases, a value 8.5% vs. 4.6% respectively; difference statistically significant paired t-test (alpha = 0.05). In those who received SIRT, LMD calculated significantly than (t-test, P < 0.005). Repeated phantom experiments an anthropomorphic torso variable Tc activity concentrations performed standard patient protocol, demonstrated improved accuracy (mean overestimated 6% 26%). Conclusions This demonstrates that be appropriate tools accurate. Minimizing errors obtaining SIRT ensuring will not exceed acceptable safety thresholds.