Gadolinium oxyorthosilicate

New materials with higher sensitivity or resolution have been designed A 3-dimensional PET scanner using gadolinium oxyorthosilicate (GSO) crystals (Surti). 

Differences between PET-CT systems apply to the number of detector rows with which the CT component is equipped. Currently, up to 64 detector rows have been integrated in PET-CT. For the PET component, different detector materials have been available. The three most common detector materials are bismuth ger-manate (BGO), lutetium oxyorthosilicate (LSO), and gadolinium oxyorthosilicate (GSO). All available PET-GT systems are equipped with a full-ring PET detector (360° coverage). The size of each detector crystal defines the spatial resolution of the tomograph, which may range from 2 to 5 mm. 

In addition to the well-established A and B forms, Wanklyn et al. (1975) have found a new form of oxyorthosilicate for gadolinium, terbium and dysprosium. Single crystals have been obtained by the flux growth method from a mixture containing PbFj, RjOj and SiOj. Only the X-ray powder patterns of these crystals have been published. It should also be noted that the new structure was obtained from only 4 of 40 batches prepared. Wanklyn et al. concluded that the structure must be somewhat unstable, yet upon heating to 1700°C the diffraction pattern remained unchanged. The crystals contained lead only as a trace impurity. 

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