Development of a Flexible End-Shield Using Tungsten Curtains for 3D PET

In the three-dimensional (3D) acquisition of positron emission tomograph (PET) without septa, random and scatter due to events from outside the field of view (FOV) become a serious problem. They decrease the signal to noise ratio and the quantitation of the image and also limit the count rate capability of the PET system. To reduce these effects, we developed a flexible end-shield using tungsten curtains (curtain-shield) that consists of a mobile stand, a cylindrical support, and flexible tungsten curtains. The tungsten curtains are made of four layers of 30 mm square, 1 mm thick tungsten plates contained in pockets of cloth. Because the tungsten curtains are flexible, they can safely be used even in body studies. Reduction of random and scatter were observed by using the curtain-shield in both phantom and human studies. Results indicate that the curtain-shield has a potential to improve the image quality of PET studies