SU‐D‐500‐05: Comparison of Gating Algorithms in 4D‐PET for Mobile Tumor Segmentation

• Published in: Medical Physics 2013-06, Vol.40 (6), p.106-106
• Main Authors: Jani, S, Dahlbom, M, White, B, Thomas, D, Gaudio, S, Low, D, Lamb, J
• Format: Article
• Language: English
• Subjects: Cancer; Kinematics; Medical image segmentation; Medical imaging; Robotics; Trajectory models
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4814022

Purpose: To quantitatively compare the accuracy of tumor volume segmentation in four different gating algorithms in gated 4D‐PET. Methods: Four acrylic spheres with inner diameters ranging from 1cm to 4cm were filled with a 11‐C solution and affixed inside a cylindrical bath of 18‐FDG. The system was attached to a robotic arm that underwent 1D motion according to large‐amplitude trajectories based on measured patient breathing trajectories. Two trajectories were used: one with and one without baseline drift. List‐mode data was split into two‐minute images at different source‐to‐background ratios (SBRs), which were gated into eight bins using two amplitude‐based (equal amplitude bins (A1) and equal counts per bin (A2)) and two temporal phased‐based gating algorithms. All gated images were segmented using a commercially available gradient‐based technique. Internal target volumes (ITVs), generated by taking the union of all eight contours per gated image, were compared to their respective ground truths. The ground‐truth ITV was defined as the volume subtended by the tumor model positions covering 99% of breathing amplitude. Superior‐inferior distances between sphere centroids in the end‐inhale and end‐exhale phases were also calculated. Results: Averaged over all sphere sizes, both trajectories, and high and low SBRs, A2 was the closest in accuracy of ITV segmentation, with a measured‐to‐expected ratio of 1.002 vs. 0.920 and 0.964 for temporal phase‐based methods (p