Nuclear medicine involves the use of radiopharmaceuticals. These consist of a specially designed molecule attached to a radioactive atom, which loses radioactivity within a short period of time and usually leaves the body within 24 hours.
Nuclear medicine cameras move across the body and rotate around it to produce 2D or 3D images of the body. They are quiet and cause no discomfort and unlike conventional radiology, they do not transmit any beams through the body.
Conventional radiology (X-rays, ultrasound, CT and MRI) usually demonstrates the structure (anatomy) of a patient’s organs. Organs can however be diseased without a change in structure. Nuclear medicine demonstrates the function (physiology) of the organs by showing the uptake and excretion of a tracer (radioactive dye) by the actual cells. It can therefore often detect disease at a much earlier stage than imaging the organ anatomy.
A recent development is the so-called “hybrid scanner”: a combined gamma camera/CT scanner. The scanner allows fusion of a 3-D nuclear medicine scan (SPECT) with a low-dose CT scan done at the same time. This technique is called SPECT-CT and allows much more accurate interpretation of images.