Radiation Sources and Hazards PDF

Radiation sources and hazards FUNDAMENTALS OF RADIATION AND RADIATION SAFETY MODULE TIMELINE 2024-25 Mock...

Radiation sources and hazards FUNDAMENTALS OF RADIATION AND RADIATION SAFETY MODULE TIMELINE 2024-25 Mock Assessment Seminar Seminar Seminar 3 1 2 MCQ Exam Lecture Lecture Lecture Lecture 2 4 6 7 Lecture Lecture Lecture Lecture Lecture Lecture 1 3 5 8 9 10 Holidays SEPTEMBER OCTOBER NOVEMBER DECEMBER JANUARY Virtual 1 3 Simulations 2 1 3 On-Campus Simulations 2 TOPICS KEY: Skills for module Fundamentals of completion Radiation Radiation Safety Radiation Protection Assessment Skills & in Context Assessment Module Learning Objectives Today’s learning outcomes Understand two different classifications of radiation Discuss the effects of exposure to ionising radiation Develop a basic understanding of radiation biology Gain an understanding of radiation risks and their magnitude Introduce a range of radiation dose measures Song of the week! Song of the week ⓘ Start presenting to display the poll results on this slide. Types of radiation  Two radiation types Non-ionising radiation Ionising radiation Low frequency (low High frequency (high energy) energy) Radio-waves, microwaves, X-rays, gamma rays, etc. infrared, visible light, UV Non-ionising radiation Low energy radiations Sufficient energy to move atoms or cause them to vibrate Main effect is heating, e.g. skin burns from UV (sunburn!) - erythema Ionising radiation High energy radiations Sufficient energy to knock electrons out of atoms → poses health risk Causes damage to tissue and DNA strands – double strand breaks irreparable Types of ionising radiation Particulate Photon Even at very low doses it Alpha Gamma has potential to cause serious and lasting Neutrons X-ray biological damage! Protons Electrons What radiation are we exposed to? Per caput dose to the UK population in 2010 - 2.7 mSv Weapons fallout 0.2% Occupation 0.02% 0% Radon & Thoron Discharge 0.01% 11% Medical 12% 48% Terrestrial Gamma 13% Cosmic 16% Intake of radionuclides ex Radon Other What is Radon gas? Radon (Rn) is a natural radioactive gas. It comes from the decay of uranium that occurs naturally in all rocks and soils and is given off at the surface of the ground. Because radon is a naturally occurring gas, then we all breath it in everyday. The radioactive particles produced from radon decay remain suspended in air. Radon levels in England/Wales Most homes have low Radon levels (200 Bq m-3 Becquerel (Bq) is the SI derived measures taken to reduce it unit of radioactivity The amount of ionising Average UK radiation dose radiation released due to = 1.3mSv radioactive decay Average Cornwall radiation dose = 7.8mSv Cosmic radiation Cosmic radiation Very energetic charged particles moving through space. When they enter the earths atmosphere they collide with, and disrupt, atoms in the upper atmosphere, producing UK average dose secondary radiation. at ground level = 0.37mSv For airline crew, By the time cosmic radiation reaches the ground its annual dose = intensity has been greatly reduced, by absorption in the 2.4mSv atmosphere. London – New York flight = 0.032mSv – approx. same as dental x-ray Internal – food, drink, tobacco Natural radionuclides in the environment may be taken up by plants and so enter the food chain. The average dose in the UK from food stuffs is 0.29 mSv. certain products contain higher concentrations of radioactive materials. Smoking 1 cigarette per day → annual dose of 0.018mSv Marine animals Annual dose up to 0.02mSv Brazil nuts Dose per 100g is 0.01mSv Bananas Per banana, dose is 0.01µSv https://etn.redmud.org/banana-equivalent-dose/ Terrestrial gamma radiation Most radionuclides in uranium & thorium series and potassium 40 emit gamma rays They’re present in soil and building materials – we’re all irradiated daily! Average UK annual dose = 0.35mSv Medical radiation UK collective dose from diagnostic radiology 2008 Largest artificial 5% CT contributor to UK 8% radiation dose is Conventional medical procedures – 19% approx. 16% of annual Interventional radiation dose! 68% Angiography Other sources Occupational – Disposals – Products - Fall out – 0.2% 0.02% 0.01% 7Gy) – 1st Nov vomiting within hours 2006 Stablised, but Died 23rdNovember significantly 2006 deteriorated after 2 weeks Late effects Appear months after exposure – can be effect of cumulative doses Organ Effect Threshold dose Lens of eye Cataract 5 Sv Skin Erythema, dry 4 Sv desquamation Gonads Impaired fertility 1 Sv Sterility 4 Sv The amazing human body! Organs/tissues sustaining Cells begin to Eye lens has no repair functional damage regain repopulate following mechanism so damage is some/most of sub-lethal exposures cumulative functionality Many interventional In Radiotherapy, patients receive large dose (15- Radiologists 60Gy) in small fractions over time – allows some develop recovery time to minimise damage to healthy tissue cataracts Skin damage – possible in fluoroscopy! Intensive X-ray use in surgical procedures can yield skin damage 6-8 weeks after multiple 18 – 21 months later angioplasty Stochastic effects As dose increases, Random process with probability of effect no dose threshold increases Latent effects – time gap between exposure and effect Mutagenesis – Carcinogenesis – production of genetic Leukeamia or solid mutations tumours  Latency period 10-4 x 20 15 Solid tumours Nominal risk of Annual risk 10 malignancy from Leukaemia uniform whole body 5 dose of 0.01Gy 0 10 20 30 40 Time after irradiation in years How does risk relate to dose? Much debate over the relationship High quality data is for high dose exposures Make a simple, reasonable assumption for protection purposes Sources of epidemiological data Radium watch dial painters Uranium miners Early medical radiation workers Patients injected with Thorotrast Residents of Marshall Islands Japanese atomic bomb survivors Evacuees from Chernobyl Risks in context Activity Risk of death Smoking 10 cigarettes per day 1 in 200 Road accidents 1 in 500 Head CT scan 1 in 14,000 Accidents at work 1 in 20,000 Transatlantic flight 1 in 35,000 Chest X-ray 1 in 1,250,000 Eating 135 g’s brazil nuts 1 in 2,500,000 Annual exposure of 1 mSv 1 in 25,000 Gamma rays are the sort of radiation you should avoid. Want proof ? Just remember how the comic strip character "The Hulk" became big, green, and ugly.