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The ECAT HRRT: performance and first clinical application of the new high resolution research tomograph

The ECAT HRRT (High Resolution Research Tomograph) is a 3D-only dedicated brain tomograph employing the new scintillator LSO and using DOI information to achieve uniform isotropic resolution across a 20 cm diameter volume. With its unique technological innovations it represents the prototype of a new generation of high resolution brain tomographs. The physical performance with respect to count rate, live time, scatter, sensitivity and resolution was evaluated with phantom studies and measurements with a point source. The HRRT's imaging performance was tested with phantoms and FDG scans performed in animal and human brains. The authors find that due to the significantly improved resolution and the large solid angle covered by the panel detectors, several issues that have been adequately solved for older generation scanners demand new attention for the HRRT. One major issue is the high randoms rate resulting partly from activity outside the field of view, which requires improved approaches to shielding and randoms correction.