Biological Effects of Ionising Radiation

							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