Performance characteristics of a new development dedicated breast PET scanner evaluated with the NEMA NU 2-2008 standard

434 Objectives A newly developed breast positron emission tomography (PET) scanner is consisting of four-layer depth of interaction (DOI) detectors. We evaluated the physical performance of the dedicated breast PET scanner with the National Electrical Manufacturers Association (NEMA) NU 4-2008 standard. Methods The detector consists of four-layer of a 32×32 lutetium oxyorthosilicate-based (LGSO) crystal array, a light guide and a 64ch position-sensitive photomultiplier tube. The size of crystal element is 1.45×1.45×4.5 mm. The detector ring has a large solid angle with an aperture 185 mm and an axial coverage of 155.5 mm (100 rings). The low- and high-energy thresholds at DOI 1st, 2nd layer and 3rd, 4th layer are set to 400-800 keV and 100-800 keV, respectively (the first layer is the patient side of the detector). Results With the NEMA NU 4-2008 standard, the main performance results were as follows: the average (radial and tangential) transverse and axial spatial resolutions (FWHM) at 5 mm and at 75 mm off axis were 1.35 and 1.72 mm and 1.34 and 1.35 mm, respectively; the absolute sensitivity of the system was 11.2% for an energy window of 100-800 keV and a timing window of 4.5 ns; the scatter fraction at the same acquisition settings was 30.1% for the rat-size phantom; the peak noise equivalent counting rate was 374 kcps at 25 MBq for the rat-size phantom. Conclusions This new dedicated breast PET scanner has good overall performance. The PET scanner including high resolution and sensitivity, and has the potential of reducing breast acquisition time to less than 5 minutes while improving small-lesion detectability