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

AdvantagesDisadvantages readily availableexpensive minimally invasivehigh radiation dose can assess physiologypoor anatomical detail

RISK FACTORS Use ionizing radiation that is known to damage cells. Cancer risk