[Physical property of emission data in simultaneous emission/transmission acquisition: evaluation for clinical application].

PURPOSE Although simultaneous emission transmission acquisition (SET) is the ideal method for positron emission tomography (PET) because the same patient position can be used for both emission and transmission scans, the quality of PET images is subject to interference by the cross-contamination of each data. In recent years, segmented attenuation correction of transmission data has made it possible to exclude the contamination from emission data. In the present study using a phantom, the physical property of emission data in SET acquisition was evaluated in comparison with that in separate scan. METHODS We measured scatter fraction, scatter projection, % random, and noise equivalent count rate in the sinogram. Next, we determined the acquisition time of the SET scan to obtain the same coefficient of variation as the separate scan in reconstructed images. RESULTS In the evaluation of the strength of the line source, the physical property of emission data in the SET scan seemed inferior to that in separate scan, and SET scanning was not effective enough to reduce the acquisition time of PET examinations. CONCLUSION SET scanning has the advantage that the same patient position can be used for emission and transmission data; however, further studies may be necessary to apply it to clinical examinations.