Mammography is the current standard for breast cancer screening, however it is acknowledged by experts in imaging that mammography is not ideal. We are studying the potential of tomographic imaging of the breast using a custom-designed breast CT scanner. The breast CT system is capable of generating 300 to 500 tomographic slices of the breast using the same radiation levels as two view mammography, and these images allow the radiologist to view regions in the breast unobstructed by overlaying normal anatomical tissue, which can obscure lesion identification and reduce cancer detection performance, especially in the dense breast. We have designed, fabricated, and tested two prototype breast CT scanners in the lab, and were the first group in the world to perform cone beam breast CT on live women. We have performed over 140 breast CT studies as of January 2008. Future advances on the breast CT system include the addition of positron emission tomography (PET), robotic biopsy, and the addition of therapeutic capabilities including radiofrequency ablation and radiation therapy.