Abstract
1084
Learning Objectives Artery-specific SPECT/CT partition model dosimetry incorporates both catheter-directed CT hepatic angiography and Tc-99m-MAA SPECT/CT to improve SIRT dosimetry.
Current Yttrium-90 selective internal radiation therapy (SIRT) dosimetric techniques have yet to embrace newer imaging modalities such as catheter-directed CT hepatic angiography (CTHA) and SPECT/CT. CTHA delineates the margins of target arterial territories more accurately than conventional hepatic angiography, shifting the pre-SIRT planning paradigm from the ‘segmental/lobar’ approach to an ‘arterial territory-based’ approach. Tc-99m-MAA SPECT/CT is superior to planar Tc-99m-MAA scintigraphy for assessing the extent of microparticle implantation and calculation of the ‘tumor-to-normal liver (T/N) ratio’. The artery-specific SPECT/CT partition model is a dosimetric technique currently in use at our institution. It incorporates both CTHA and Tc-99m-MAA SPECT/CT to improve dosimetric accuracy in pre-SIRT planning. CTHA provides the liver volume of each targeted arterial territory; Tc-99m-MAA SPECT/CT provides the functional tumor volumes and calculates the SPECT-based T/N ratio for each target arterial territory. In cases of selective liver sparing in combination with other locoregional modalities (e.g. radiofrequency ablation), artery-specific SPECT/CT partition model dosimetry preserves the artery-specific dosimetric integrity to tumor, non-tumorous liver and lung compartments. Safety and efficacy of ‘radiation segmentectomy/lobectomy’ are improved due to more precise and reliable radiation dose estimates. It may be possible to use artery-specific SPECT/CT partition modeling to treat hypovascular liver tumors or even non-liver solid organ tumors e.g. renal cancers i.e. ‘radiation nephrectomy’. We found favorable patient outcomes using artery-specific SPECT/CT partition model dosimetry. The overall effect is individualized state-of-the-art Yttrium-90 SIRT with improved therapeutic safety and efficacy