Fig. 1

⁹⁰Y PET (top) and fused PET/CT (bottom) corresponding to the phantom studies showing MS (green) and PS (red). Example rays from PETEdge tool are also shown. A threshold of 18% (orange) provided the best volume estimate (61.8 cc) to the MS in (a) (cold background), while the same 18% threshold overestimated the sphere volume (102.4 cc) in (b) (warm background). A 32% threshold (not shown) gave the best volume estimate (61.7 cc) for the MS in (b). Segmentation overlays on the zoomed in PET component in (a),(b),(c) corresponding to the the fused PET/CT in (d), (e), and (f), respectively