NUCLEAR MEDICINE

NUCLEAR MEDICINE

High Energy Photon

Ionizing Radiation --Radiopharmaceutical

Exposes Detector

Projection Data

Dynamic / Physiologic

Here we have an example of a nuclear medicine bone scan with anterior and posterior views.

This branch of radiology uses radioisotopes for imaging.

The radioisotopes produce gamma-rays that are emitted by the patient following intravenous injection of the isotope.

The rays are detected by a gamma camera.

Radioisotope investigation allows the assessment of function as well as structure.

The commonest radioisotope used is technetium, which has a half-life of 6 h.

Common radioisotope investigations

• Bone scan - Tc phosphonate to look for metastases• Lung ventilation - Tc DTPA aerosol, krypton gas• Lung perfusion - Tc micro-aggregate albumin to

assess perfusion• ventilation/perfusion scans for investigation of

pulmonary emboli• Cardiovascular - thallium scanning to look for

cardiac perfusion abnormalities • Thyroid - iodine or technetium to assess thyroid

function/nodules

• With Nuclear Medicine a radioactive drug is administered, a pharmaceutical portion of the drug has been created to localize to a type of tissue.

• The radioactive tag of the pharmaceutical serves to identify the site of accumulation.

• The detector or gamma camera which is similar to a Geiger Counter measures the radiation distribution and maps it to a region.

NUCLEAR MEDICINE EXAMPLES

Liver

Bone

PET scan

Advantages Disadvantages

readily available expensive

minimally invasive high radiation dose

can assess physiology poor anatomical detail

RISK FACTORS • Use ionizing radiation that is known to damage

cells.

• Cancer risk