What is radioactivity? Clinical use of radioactive isotope.

Radioactivity:

It is the spontaneous emission of accelerated particles(radiation) from an unstable isotope by radioactive decay.

Clinical use of radio active isotope:

A. Diagnostic use

1. Iodine uptake test for diagnosis of thyroid disorders.
2. Radio immune assay of hormones for diagnosis of hormone disorders.
3. Organ scanning e.g. bone scan, brain scan, thyroid scan.
4. Absorption test e.g. for iron. vitamin B12
5. Isotope renogram for mesurement of GFR and renal clearance.
6. RBC life span measurement.

B. Therapeutic use, e.g. radiotherapy in treatment of malignancy.

C. Use in tracer technique: isotopes are used as tracer in metabolic studies to outline the metabolic pathways.

D. Measurement of volumes and spaces. e.g. ECF volume, Blood volume, plasma volume, RBC volume.

E. Measurement of regional blood flow. e.g. Cerebral blood flow, coronary blood flow, renal blood flow.

F. Sterilization of medical instruments.