A positron tomograph with 600 BGO (bismuth germanate) crystals and 2. 6 mm resolution

We describe the imaging performance of the Donner 600-Crystal Positron Tomograph, a single 600 cm diam ring of 3 mm wide bismuth germanate (BGO) crystals coupled individually to 14 mm phototubes. With a pulse height threshold of 200 keV and a slice thickness of 5 mm, the sensitivity is 7024 eventssec per ..mu..Ciml in a 20 cm cyliner of water. The measured rates for 18 ..mu..Ciml are 95,000 truessec plus 20,000 randomsec. A 0.3 mm diam /sup 22/Na line source near the center of the tomograph has a circular point spread function (PSF) with a full-width at half-maximum (fwhm) of 2.6 mm. At 5 cm from the center the PSF is elliptical with a fwhm of 2.7 mm tangential )times) 3.2 mm radial. At 10 cm the PSF has a fwhm of 2.8 mm tangential )times) 4.8 mm radial. Attenuation data are accumulated with a 20 mCi /sup 68/Ge orbiting transmission source and 100 million coincident events are collected in 200 sec. 20 refs., 9 figs., 5 tabs