[Performance of a multispect 2 gamma camera for imaging 511-keV gamma rays]

The performance of a modified Multispect 2 gamma camera, which was supplied with two pairs of collimators constructed for imaging positron emitters was tested. The measurements involved the determination of sensitivity and of spatial resolution. The septal penetration was calculated approximately using two different methods. The spatial resolution determined by FWHM as measured by planar imaging in water at 10 cm distance 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 sensitivity measured with 18F was 66 cpm with collimator 511-A and 98.7 cpm/37 kBq with collimator 511-B. The high sensitivity with collimator 511-B may be explained, at least partially, by the high septal penetration.