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[[file:Bone_Scan_1Bone_Scan_2.jpg|200px|left|thumb|'''Figure 6:''' Example of a normal (2a) and abnormal (2b) whole-body bone scan. Note: a. illustrates a normal bone scan with expected excreted activity in the kidneys (arrow) and bladder (white arrow head). ]][[file:Bone_Scan_2.jpg|200px|left|thumb|'''Figure 7:''' Example of a normal (2a) and abnormal (2b) whole-body bone scan. Note: b. illustrates Illustrates an abnormal bone scan in a patient with multiple skeletal metastatic deposits, some of which are marked with arrows. Source: Images Courtesy of Health Sciences Centre - Winnipeg, Manitoba.]][[file:SPECT_CT_gamma.jpg|200px|thumb|'''Figure 87:''' Example of a SPECT/CT gamma camera (Source: © 2018 Siemens Healthcare GmbH. All Rights Reserved. Product photo provided courtesy of Siemens Healthcare GmbH) ]]Nuclear medicine uses radioactive substances, called radiopharmaceuticals, in the diagnosis and treatment of a range of diseases. These substances are chosen or especially developed to be taken up predominantly by one organ or one type of cell in the body. Nuclear medicine offers unique diagnostic information in oncology, cardiology, endocrinology, neurology, nephrology, urology and other areas. Such information is not obtainable, or obtainable only with less accuracy, by other modalities. For nuclear medicine diagnostic procedures, trace amounts of radiopharmaceuticals are administered to patients through injection into veins (intravenous), skin (intradermal) or tissues (intraparenchymal) as well as breathing in (inhalation) or eating/drinking (ingestion). After intake, the function, or physiology, of various tissues, organs or organ systems can be demonstrated. For example, in cancer patients, nuclear medicine imaging can be used for diagnosis (i.e. is a cancer present), staging (i.e. how far has it spread), assessment of response to therapy or of possible disease recurrence. Nuclear medicine cameras are now commonly combined with a CT unit (e.g. hybrid SPECT/CT and PET/CT) which allows precise anatomic localisation of pathology. (Figure 8, Figure 6, 7)