Segmented attenuation correction using 137Cs single photon transmission

Using a ¹³⁷Cs single photon transmission source for transmission scanning allows a higher photon flux and thus, better transmission statistics compared to coincidence transmission scanning. However, ¹³⁷Cs suffers from a high scatter fraction as well as emission contamination, both leading to an underestimation of the attenuation values. On our NaI- and GSO-systems this is currently compensated by subtracting emission contamination, scatter-scaling and re-mapping. Histogram based segmentation, widely used to shorten the scan time on ⁶⁸Ge devices, inherently is capable to compensate for a potential bias in the attenuation values. We have investigated segmented attenuation correction for ¹³⁷Cs transmission scans with NaI(Tl) PET scanners in previous work, and came to the conclusion that our current processing was superior to the formerly used segmentation routine. In this paper we re-investigate segmentation, however, using a more sophisticated algorithm. Our focus was mainly to improve the accuracy of our transmission scans rather than shorten the scan times. However, the potential to reduce the scan duration was investigated as well