System design and performance characteristics of newly developed whole-body multislice single photon emission computed tomograph

The authors have developed a new whole-body multislice single photon emission computed tomograph (SPECT). The scanner consists of three detector rings with 128 NaI crystals (14x26x30 mm) in each ring, providing three tomographic slices at 30 mm intervals. The detectors are equally arranged around the ring of 66 cm diameter with packing ratio of 0.86. The patient aperture and the field of view are 50 cm and 35 cm, respectively. Two types of focused collimators, of high resolution (HR) and high sensitivity (HS), are equipped. Linear scan and transmission scan can also be performed using the HS collimator. The radioactivity monitored by a single probe detector as well as the ECG signals can be recorded during the scan. The spatial resolution (FWHM) was 14.2 mm in the center of the field with HR collimator. The axial resolution (FWHM) was 24 mm and 34 mm for HR and HS collimator, respectively. The sensitivity measured with 20 cm diameter cylindrical phantom filled with Tc-99m solution was 5.7 and 17 kcps/μCi/ml for HR and HS collimator, respectively. The high sensitivity allows dynamic SPECT scan in various organs, such as in the brain with 3 mCi of I-123 iodoamphetamine (every 2 min) and in the heart with 3 mCi of Tl-201 (every 5 min). Gated cardiac pool SPECT scan can also be performed. Thus this machine will be useful for the assessment of regional tracer kinetics of many compounds labeled with gamma emitting radionuclides