SIMS MICROSCOPY IN THE BIOMEDICAL FIELD

We attempted to indicate the requirements for biomedical applications of SIMS microscopy. Sample preparation methodology should preserve bot h the structural and the chemical integrity of the tissue. Furthermore , it is often necessary to correlate ionic and light microscope images . This implies a common methodological approach to sample preparation for both microscopes. The use of low or high mass resolution depends o n the elements studied and their concentrations. To improve the acquis ition and processing of images, digital imaging systems have to be des igned and require both ionic and optical image superimposition. Howeve r, the images do not accurately reflect element concentration; a relat ive quantitative approach is possible by measuring secondary ion beam intensity. Using an internal reference element (carbon) and standard c urves the results are expressed in mu-g/mg of tissue. Despite their li mited lateral resolution (0.5-mu-m) the actual SIMS microscopes are ve ry suitable for the resolutio of biomedical problems posed by action m odes and drug localization in human pathology. SIMS microscopy should provide a new tool for metabolic radiotherapy by facilitating dose eva luation. The advent of high lateral resolution SIMS imaging (< 0.1-mu- m) should open up new fields in biomedical investigation.