Biological Effects of Ionising Radiation

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Biological Effects of Ionising Radiation
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Radio Sensitivity

• Radio Sensitive Tissues
• Radio Resistant Tissues

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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

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Radio Resistant Tissues

• Bone
• Liver
• Kidney
• Muscle
• Nerves

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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.

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Radiation Effects

• Stochastic Effects
• Non-Stochastic Effects

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Stochastic Effects

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

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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

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Effects of Acute Radiation Exposure

• On the Blood
• On Digestion
• On the Central Nervous System

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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

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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

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Central Nervous System

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