PHYSICAL PERFORMANCE OF A MULTISPECT-2 GA MMA-CAMERA FOR IMAGING POSITRON EMITTERS

The performance of a modified Multispect 2 gamma camera, which was sup plied with two pairs of collimators constructed for imaging positron e mitters was tested. The measurements involved the determination of sen sitivity and of spatial resolution. The septal penetration was calcula ted approximately using two different methods. The spatial resolution determined by FWHM as measured by planar imaging in water at 10 cm dis tance from the collimator was evaluated as 14.0 mm with collimator 511 _A and 12.5 mm with collimator 511_B. Using a Gaussian fit of the line -spread function septal penetrations of 12% with collimator 511_A and of 36% with collimator 511_B were calculated. The absolute system sens itivity measured with F-18 was 66 cpm with collimator 511_A and 98.7 c pm/37 kBq with collimator 511_B. The high sensitivity with collimator 511_B may be explained, at least partially, by the high septal penetra tion.