Evaluation of Breast Tumor Detectability With Two Dedicated, Compact Scintillation Cameras

As part of the development of dedicated scintillation cameras for breast imaging, we compared the performances of two dedicated cameras with a standard clinical camera (Siemens Orbiter). One dedicated camera was based on a single position-sensitive photomultiplier tube (PSPMT) coupled to a 6 cm by 6 cm by 6 mm NaI(Tl) crystal. The other (LumaGem) was based on multiple-PSPMTs coupled to a 2 mm 2 mm by 6 mm matrix of NaI(Tl) crystals. Spatial resolution was measured with all cameras as a function of depth. The ability of the cameras to image small superficial tumors was tested with a phantom consisting of six hot cylindrical tumors of height 3 mm and varying diameters against a warm background. The tumors were imaged at various depths within the background using tumor-to-background activity concentration ratios of 10 : 1 and 5 : 1. Tumor contrast and signal-tonoise ratio were measured in all cases for all cameras. The dedicated cameras show improved shallow depth of field spatial resolution, contrast, and signal-to-noise ratio relative to the clinical camera when imaging the breast tumor phantom. This, with the additional advantage of being able to position the cameras close to the region of interest, suggests that dedicated cameras will play a strong role in scintimammography and other shallow depth of field applications.