Simulation and Validation of Point Spread Functions in Pinhole SPECT Imaging

• Published in: IEEE transactions on nuclear science Vol. 53; no. 5; pp. 2729 - 2735
• Main Authors: Funk, T., Kirch, D.L., Mingshan Sun, Izaguirre, E.W., Koss, J.E., Prevrhal, S., Hasegawa, B.H.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2006; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analytical models; Animals; Collimators; Computational efficiency; Computational modeling; Computer simulation; Computing time; Geometry; Imaging; Mathematical models; Medical imaging; Monte Carlo methods; Monte Carlo simulations; Optical collimators; pinhole; Pinholes; point spread function; Ray tracing; Reconstruction algorithms; septal penetration; Shape; Simulation; Single photon emission computed tomography; single photon emission computed tomography (SPECT); Solid modeling; Studies
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2006.878009

Modeling and assessment of point spread functions (PSFs) of pinhole collimators is essential for the design of small animal single photon emission computed tomography (SPECT) imaging systems, and are gaining increasing importance with the advent of multipinhole imaging techniques. PSFs also can be used in resolution recovery methods implemented in reconstruction algorithms. Therefore, we have developed and validated a ray-tracing approach to calculate PSFs and absolute detection efficiency of pinhole collimators in radionuclide imaging. The PSFs were calculated for user defined pinhole and source geometries with multiple rays to account for collimator penetration. For validation we compared our simulations to analytical models, Monte Carlo simulations from literature, and experiments with 99 m Tc sources using a variety of pinhole geometries including knife and keel edges. We find that shape and magnitude of the simulated PSFs are in very good agreement with analytical and experimental results. Importantly, our simulations show that the absolute detection efficiency of pinhole systems can be computed with an accuracy error of less than 10% using the ray-tracing approach. In contrast to Monte Carlo simulations ray-tracing simulations are computational very efficient and therefore very fast. In conclusion, we developed a ray-tracing method that calculates PSFs and detection efficiencies for different pinhole and source geometries quickly and reliably