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Radiation
This document discusses ionizing and non-ionizing radiation. It defines ionizing radiation as radiation capable of producing ions through direct or indirect interaction with matter, while non-ionizing radiation does not have a wavelength sufficient for ionization. The document discusses the different types of ionizing radiation including electromagnetic radiation like x-rays and gamma rays, and corpuscular radiation like alpha particles, beta particles, neutrons, and protons. It also discusses the mechanisms of radiation damage, relative biological damage of different types of radiation, sources of background radiation exposure, and medical uses and effects of ionizing radiation.
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Radiation
- 1. Dr. Dalia El-Shafei Ass.Prof., CEOM Department, Zagazig University http://www.slideshare.net/daliaelshafei
- 2. Radiation is thestraight line transport of energy through space or matter Electromagnetic or particulate radiation capable of producing ions, directly or indirectly when passing through matter. Ionizing radiation “IR” Electromagnetic radiation with a wave length not sufficient for ionization. Non ionizing radiation “NIR”
- 4. Mechanism of action: a)Ionization: is to ripe electrons away from atoms & molecules. b) Excitation of molecules. Electromagnetic radiation “EMR” • X- ray • Gama “γ”ray Corpuscular radiation • Alpha “α” particles “low power of penetration & great power of ionization”. • Beta “β” particles “greater power of penetration”. • Neutrons • Protons • Electrons.
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- 7. OH . (hydroxyl radical) H . Radiation Damage Watermolecule -ray 2 OH . H2O2 What happens when the water molecule is struck by the gamma ray?
- 8. Alpha Particles Stopped bya sheet of paper Beta Particles Stopped by a layer of clothing or <1 inch of a substance (e.g. plastic) Gamma Rays Stopped by inches to feet of concrete or <1 inch of lead Radiation Source Neutrons Stopped by a few feet of concrete :: 1:100:10,000
- 9. Radiation Damage Radiation weightingfactor, WR or relative damage that can be caused in a biological system. Radiation WR Alpha 20 Fast Neutron 10 Slow Neutron 5 Beta 1 Gamma Rays 1 Increasing biological damage
- 11. Annual Dose fromBackground Radiation Total US average dose equivalent = 360 mrem/year Total exposure Man-made sources Radon Internal 11% Cosmic 8% Terrestrial 6% Man-Made 18% 55.0% Medical X-Rays Nuclear Medicine 4% Consumer Products 3% Other 1% 11%
- 13. Uranium miners & atomic millers Nuclear reactors& atomic energy plant Radiologist Scientists using radioactive materials
- 14. Ionizing radiation in medicine Treatment “Radiation therapy" Radiotherapy HighEnergy Gamma Rays High Energy X-Rays Brachytherapy Diagnosis Sterilization
- 16. Radiation effect Early (Deterministic only) LocalRadiation injury General Acute radiation syndrome Acute radiation sickness Late Deterministic Radiation dermatitis Radiation cataracta Teratogenic effects Stochastic Tumors Leukaemia Genetic effects
- 20. Whole body irradiation Exposureto doses > 1Gy → acute radiation syndrome “Prodromal symptoms (nausea, vomiting) & bone marrow depression (leukaemia, anaemia, thrombocytopenia)”. Local irradiation Skin reactions according to the dose “mild erythema → tissue necrosis & ulceration”.
- 24. Chronic radiation sickness. Chronic radio- dermatitis:disturbed sensation, focal hyperkeratosis, congestive hyperaemia, painful cracks & ulceration with malignant changes. Eye cataract: starts at posterior pole of lens capsule. Carcinogenic & hereditary harm. Chronic effect