Comparisons of multiple photon coincidence imaging techniques

The authors compare analytically techniques for multiple-photon coincidence imaging in terms of spatial resolution, detector efficiency (or simply efficiency), and system sensitivity for a spherical water phantom (or simply sensitivity). One analysis consists of comparing photon-photon coincidence single-photon-emission computerized tomography (PP-SPECT) with the angularly unconstrained, electronically collimated triple-photon coincidence imaging technique (TPCIT). A second analysis compares positron-emission tomography using time-of-flight information (TOF-PET) with angularly constrained, electronically collimated TPCIT, The angularly unconstrained TPCIT has a similar spatial resolution, higher efficiency, and higher sensitivity when compared to PP-SPECT. The angularly constrained TPCIT has similar spatial resolution, lower efficiency, and lower sensitivity when compared to TOF-PET. However, the angularly constrained TPCIT can, for brain imaging, reduce the localization range of photon-emission sites along projection rays from about 20 cm to about 1 cm during data acquisition, while TOF-PET currently reduces the range to about 7 cm