Rapidly proliferating tissue incorporates more phosphorus than normal. Thus, following administration of radioactive phosphorus (32P), tumors emit increased amounts of radiation which can be detected. With the proper test technique, a correct diagnosis rate of 96-100% is quoted in the literature. By comparison, between 4 and 20% of all eyes enucleated for suspected malignant melanoma without prior 32P testing contained no neoplasm histologically. The radiation exposure is minimal due to the short half-life of 32P and the low penetration of beta-particles. However, the test usually involves a small operation (conjunctiva and Tenon incision). Testing with gamma rays, however, is not yet wholly satisfactory due to the lack of a suitable gamma-ray detector.