The Model 800 enables measure of scatter fraction and count rate performance as outlined in NEMA NU2-2001. Scatter fraction is a measure of the system sensitivity to scatter while count rate performance is an indication of scanner performance as a function of activity. The PET Scatter Phantom is a solid right circular, polyethylene cylinder with a specific gravity of 0.96. A 6.4 mm hole is drilled parallel to the central axis of the cylinder, at a radial distance of 45 mm. For ease of handling the cylinder consists of three segments that are assembled during testing. The test phantom line source insert is a clear polyethylene plastic tube of 800 mm in length, with an inside diameter of 3.2 mm and outside diameter of 4.8 mm. The central tube can be filled with a known quantity of activity and threaded through the 6.4 mm hole in the test phantom.