A method for determination of the timing stability of PET scanners

• Published in: IEEE transactions on medical imaging Vol. 24; no. 8; pp. 1053 - 1057
• Main Authors: Thompson, C.J., Goertzen, A.L.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.08.2005; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Attenuation; Calibration; Crystals; Detectors; Energy resolution; Equipment Failure Analysis - methods; High-speed electronics; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Instruments; Positron emission tomography; Positron-Emission Tomography - instrumentation; Positron-Emission Tomography - methods; Probes; Reproducibility of Results; Sensitivity and Specificity; Stability; Time Factors; time-of-flight; Timing; timing alignment; timing stability
• ISSN: 0278-0062; 1558-254X
• DOI: 10.1109/TMI.2005.852072

We report on the timing resolution and stability of the MicroPET R4 PET scanner. Its detectors have energy resolutions in the range of 25% and previously reported timing resolutions 3.2 ns. Our preliminary evaluation of this instrument showed that artefact-free normalization sinograms could only be obtained with a timing window of 10 ns or more in spite of a timing resolution of 3.2 ns. This instrument uses high-speed electronics albeit with 2-ns timing clock. We performed sham transmission scans with nothing in the field of view, and a range of timing windows from 2 to 14 ns and used a 14-ns timing blank scan to generate effective attenuation sinograms as a function of timing window. These showed trues count-rates which fit well to a ERF (/spl tau/) function. However, the effective attenuation value, which should be 1.0, changes from block to block and becomes very high in some blocks (>3.5 at 6 ns) suggesting the need for timing alignment. A method was devised to measure the timing stability to a precision better than the timing bin width of 2 ns.