Biological Effects of Ionising Radiation Radio Sensitivity Radio

Biological Effects of Ionising Radiation

Radio Sensitivity • Radio Sensitive Tissues • Radio Resistant Tissues

Radio Sensitive Tissues • Reproductive cells of the ovary and the Testis • Blood forming Tissues in bone marrow, spleen, lymph nodes • Epithelium of the Skin • Epithelium of the Intestinal Tract

Radio Resistant Tissues • • • Bone Liver Kidney Muscle Nerves

Effects of Radiation • Primary Effects occur when the initial interaction is with atoms in cells like those in DNA molecules. • Secondary Effects occur with the formation of free radicals which are very reactive and can chemically attack molecules such as DNA.

Radiation Effects • Stochastic Effects • Non-Stochastic Effects

Stochastic Effects • The probability of the effect increases with the dose. • No established threshold. • Examples: Cancer, Genetic Mutations

Non-Stochastic Effects (Deterministic) • The severity of the effect increases with the dose. • Generally a threshold exists. Below the threshold, no effects occur. • Effects often result from the collective injury of many cells. • Examples: Cataracts, Skin Burns, Lowering of Blood Cell Counts

Effects of Acute Radiation Exposure • On the Blood • On Digestion • On the Central Nervous System

On the Blood • Dose level between 200 and 1000 rad • Damages red blood cell forming organs loss of breath, tiredness • Affects white blood cell production reduced ability to fight infection • Lowered platelet count - hemorrhaging and slower healing process • Death by infection and hemorrhaging

On Digestion • • Dose level between 1000 and 5000 rad Stops new epithelial cells and absorption Nausea and vomiting Dehydration from diarrhea and low water absorption • Electrolyte imbalance • Death by Circulatory collapse from loss of fluids

Central Nervous System • • • Dose Level greater than 5000 rad Convulsions Tremors Lethargy Death by respiratory/brain failure