Bone scintigraphy (e.g. "bone scan") with Tc-99m diphosphonates is one of the most common imaging radioisotope procedures in departments of nuclear medicine worldwide, with several thousand performed every year in a busy nuclear medicine service. Despite giving fast and accurate skeletal surveys in conditions ranging from metastatic cancer, to fractures, to infection, the technology has seen little change since the early 1970's. The Anger camera remains the instrument of choice for taking serial images of a patient's skeleton, and since the late 1970's SPECT (Single Photon Emission Computed Tomography) - essentially "nuclear CT imaging of 3-D distribution of radiotracer" has been added to improve contrast resolution and lesion placement.