Influence of Rotation Increments on Imaging Performance for a Rotatory Dual-Head PET System

Abstract

For a rotatory dual-head positron emission tomography (PET) system, how to determine the rotation increments is an open problem. In this study, we simulated the characteristics of a rotatory dual-head PET system. The influences of different rotation increments were compared and analyzed. Based on this simulation, the imaging performance of a prototype system was verified. A reconstruction flowchart was proposed based on a precalculated system response matrix (SRM). The SRM made the relationships between the voxels and lines of response (LORs) fixed; therefore, we added the interpolation method into the flowchart. Five metrics, including spatial resolution, normalized mean squared error (NMSE), peak signal-to-noise ratio (PSNR), contrast-to-noise (CNR), and structure similarity (SSIM), were applied to assess the reconstructed image quality. The results indicated that the 60° rotation increments with the bilinear interpolation had advantages in resolution, PSNR, NMSE, and SSIM. In terms of CNR, the 90° rotation increments were better than other increments. In addition, the reconstructed images of 90° rotation increments were also flatter than that of 60° increments. Therefore, both the 60° and 90° rotation increments could be used in the real experiments, and which one to choose may depend on the application requirement.

Performance evaluation of a rotatory dual-head PET system with 90̂increments for small animal imaging

“…The poor resolution in the direction perpendicular to the detector head has been improved by a 90°-rotation operation. Recently, we further studied the effect of different rotation increments (36°, 45°, 60°and 90°) with the software of Geant4 Application for Tomographic Emission (GATE) v6.2 [19]. The qualitative and quantitative results indicated that the 60 • and 90 • rotation increments had advantages over the other increments in spatial resolution and noise levels, and which one to choose might depend on the distance between the detector heads or the application requirement.…”