8.6 Commercial Camera Overview

The ring tomograph market is led by CTI PET systems, who are the worlds largest manufacturer of PET equipment. They produce four different scanners of differing cost and performance ranging from the ECAT ART, which utilizes two incomplete rings of BGO that require rotation in order to obtain complete imaging, up to the ECAT EXACT HR+ ( High Resolution plus) which has both high-resolution and high count-rate capabilities for the high-end clinical research market. However, an important point to note is that all of these systems are based on the same block detector design. In fact, none of the main commercial cameras differ substantially from each other. This can be seen from Table 8.10. The few differences seen are due to the scintillator material where an alternative to BGO has been used. For instance, the improved energy resolution of GSO and the consequently tighter energy window. Both LSO and GSO allow a much shorter coincidence window due to their faster decay times and higher light yields. The use of a faster scintillator can also reduce the scanning time required, down to one half of the time for LSO as compared with BGO. Also, both LSO and GSO are said to make the resulting image crisper due to the higher light yield, thus allowing a more accurate centroiding. It should be noted that the EXACT scanner is now also available in LSO, called the ACCEL.