A practical method for randoms subtraction in volume imaging PET from detector singles countrate measurements
- Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Radiology
Randoms subtraction in a volume imaging PET scanner is a significant problem due to the high singles countrates experienced. The delayed coincidence method requires double counting of randoms events and results in a lowered countrate capability. Calculations based on detector singles countrates require complex corrections for countrate dependent livetime and event acceptance due to the camera coincidence processing between the detector and rebinned randoms countrates. The profile distribution method has been used to estimate and subtract both scatter and randoms background but this method is a compromise and couples these 2 sources of background together. In order to avoid these problems and provide accurate subtraction of both the distribution and magnitude of randoms contamination in the scan data the authors have developed an alternative singles based method. The singles distributions are measured across the detectors and are used to construct a randoms distribution sinogram. This distribution is scaled to the appropriate rebinned randoms countrate by means of a lookup table of randoms countrate vs detector singles countrate, generated from phantom calibrations. The advantages of performing randoms subtraction by this method are: (1) there is no increase in camera deadtime, (2) the method compensates for nonuniformities in randoms distributions due to both the activity distribution and nonuniform geometric response of the camera for on and off bankpairs, and (3) it deals with randoms subtraction independently of scatter so that different scatter correction routines may then be applied to the data.
- DOE Contract Number:
- FG02-88ER60642
- OSTI ID:
- 276530
- Report Number(s):
- CONF-951073-; ISSN 0018-9499; TRN: 96:018035
- Journal Information:
- IEEE Transactions on Nuclear Science, Vol. 43, Issue 3Pt2; Conference: IEEE nuclear science symposium and medical imaging conference, San Francisco, CA (United States), 21-28 Oct 1995; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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