1. Based on studies in seventy-five patients, a technique is described for body surface activity measurements over localised skeletal lesions up to one month after injection of the λ-emitting isotopes Ca47 and Sr85. 2. The activity was high over skeletal lesions like fracture, metastatic cancer, eosinophilic granuloma, chondroma, osteomyelitis and Paget's disease. 3. The high isotope uptake is interpreted as evidence of an increased rate of bone tissue turnover. 4. These findings suggest that external counting of Ca47 and Sr85 may be used for quantitation of the rate of formation of normal and pathological bone tissue. A special application would be localisation and delineation of metastatic cancer in cases where radiographic evidence is uncertain or non-existent.
