New design of a gamma camera detector with reduced edge effect for breast imaging

In recent years, there has been a growing interest in developing small gamma cameras dedicated to breast imaging. We designed a new detector with trapezoidal shape to expand the field of view (FOV) of camera without increasing its dimensions. To find optimal parameters, images of point sources at the edge area as functions of the angle and optical treatment of crystal side surface were simulated by using a DETECT2000. Our detector employs monolithic CsI(Tl) with dimensions of 48.0x48.0x6.0 mm coupled to an array of photo-sensors. Side surfaces of crystal were treated with three different surface finishes: black absorber, metal reflector and white reflector. The trapezoidal angle varied from 45o to 90o in steps of 15o. Gamma events were generated on 15 evenly spaced points with 1.0 mm spacing in the X-axis starting 1.0 mm away from the side surface. Ten thousand gamma events were simulated at each location and images were formed by calculating the Anger-logic. The results demonstrated that all the 15 points could be identified only for the crystal with trapezoidal shape having 45o angle and white reflector on the side surface. In conclusion, our new detector proved to be a reliable design to expand the FOV of small gamma camera for breast imaging.