Abstract
Modern PET systems utilize rotating rod sources and sinogram windowing for transmission scan and are capable of simultaneous emission-transmission data acquisition. Count rate capability of a PET system using BGO is mainly limited by deadtime of block detectors. Deadtime of a BGO block detector is directly associated with the rate of single events. In a simultaneous acquisition, moving rod sources generate a spatially varying singles distribution which rotates synchronously with rod motions. Emission activities create a nearly uniform singles distribution which is static or varies slowly depending on the half life of radioisotope. System deadtime is characterized for different sources of activity in a simultaneous acquisition. Typically, there are 60 to 150 MBq Ge-68 in each of the three rods causing 26% peak-to-peak variation in the instant detector deadtime. Time-averaged deadtime in transmission sinogram has a variation of 30% peak-to-peak. Rod activities create a 4 to 10% peak-to-peak variation in the time-averaged deadtime in emission sinogram of a simultaneous scan. The current deadtime correction method results a 10% error in simultaneously acquired emission sinogram with 60 MBq in each rod and 74 MBq in a uniform phantom. A spatially variant deadtime correction technique was developed. Error was reduced to 4% for the same study.
| Original language | English |
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| Pages | 1489-1493 |
| Number of pages | 5 |
| State | Published - 1997 |
| Event | Proceedings of the 1997 IEEE Nuclear Science Symposium - Albuquerque, NM, USA Duration: Nov 9 1997 → Nov 15 1997 |
Conference
| Conference | Proceedings of the 1997 IEEE Nuclear Science Symposium |
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| City | Albuquerque, NM, USA |
| Period | 11/9/97 → 11/15/97 |