Nuclear Medicine uses small amounts of radioactive materials to create images of various organs in the body. Unlike some of the other imaging techniques, these images usually reflect various types of activity in the tissues, thus reflecting changes in function of the cells in the body. Techniques involve injection or ingestion of pharmaceuticals that enable imaging based on molecular level changes, allowing detection of abnormalities in early stage of diseases, before it is apparent on anatomic images obtained by x-ray or ultrasound. Nuclear Medicine uses various scans, including PET scans, to assess response to treatment before it is detectable by other means. This allows faster, and therefore, more effective adjustment of treatments. Nuclear Medicine radiologists can also treat some disorders using radioactive pharmaceuticals designed to attack some tumors.