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Imaging in Nuclear Medicine

The following two techniques use different properties of radioactive elements to create an image.
- Bone scanning
- Positron emission tomography (PET)

Bone Scanning

• This detects radiation from a radioactive substance (technetium-pp methyldiphosphate) that, when injected into the body, collects in bone tissue.
• The substance accumulates in areas of high metabolic activity and so is useful for detecting tumours, which generally have high metabolic activity.

PET scanning

• The patient is injected with a radioactive substance and placed on a flat table that moves in increments through a "donut" shaped housing.
• The circular gamma ray detector array has a series of scintillation crystals, each connected to a photomultiplier tube.
• The crystals convert the gamma rays, emitted from the patient, to photons of light, and the photomultiplier tubes convert and amplify the photons to electrical signals.
• These electrical signals are then processed by the computer to generate images.
• The table is then moved, and the process is repeated, resulting in a series of thin slice images of the body over the region of interest (e.g. brain, breast, liver).
• These thin slice images can be assembled into a three dimensional representation of the patient's body.

Nuclear medicine imaging is useful for detecting:
- tumors
- aneurysms (weak spots in blood vessel walls)
- irregular or inadequate blood flow to various tissues
- blood cell disorders and inadequate functioning of organs, such as thyroid and pulmonary function deficiencies.

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