POSITRON EMISSION MAMMOGRAPHY (PEM) - A PROMISING TECHNIQUE FOR DETECTING BREAST-CANCER

We are developing a high specificity technique for detecting the incre ased metabolic rate of breast tumours. The glucose analog FDG is known to concentrate in breast tumours rendering them easily detectable in conventional PET scans Since PET is a relatively expensive imaging tec hnique it has not been used routinely in the detection of breast cance r, Positron emission mammography (PEM) will provide a highly efficient , high spatial resolution, and low cost positron imaging system whose metabolic images are co-registered with conventional mammography. Coin cidences between two BGO blocks cut into 2 x 2 mm squares coupled to t wo 7.5 cm square imaging PMTs are detected and back-projected to form real-time multiple plane images. The design is about 20 times more sen sitive than a conventional multi-slice PET body scanner; so much less radio-pharmaceutical can be used, reducing the patient dose and cost p er scan, Prototype detectors have been made and extensive measurements done. The device is expected to have an in-plane spatial resolution a bout 2 mm FWHM, Besides the application as a secondary screening tool the device may be beneficial in measuring a rumour's response to radio -therapy or chemo-therapy, as well as aiding the surgeon in optimizing the removal of malignant tissue.