Buxton & District Science Discussion 1 Radiation Protection Marge Rose August 2013

Buxton & District Science Discussion 2 Protection of people From ionising radiation Scope of talk

Buxton & District Science Discussion 3 Ionisation Certain types of radiation can ionise atoms

Buxton & District Science Discussion 4 Types of ionising radiation X-rays Gamma rays Alpha particles Beta particles (or radiation) Neutrons, protons etc.

Buxton & District Science Discussion 5 Types of ionising radiation X-rays Gamma rays Alpha particles Beta particles (or radiation) Neutrons, protons etc.

Buxton & District Science Discussion 6 Fear and the Perception of risk Eating a bananaGoing to Cornwall on holiday for a fortnight Living within 50 miles of a nuclear power plant for a year Having a PET scan of the head Working as an airline pilot for a year Having a dental x-ray Having a CT scan of the headWorking in a nuclear power station for a year Standing in the grounds of Chernobyl for an hour Living in Buxton for a year

Buxton & District Science Discussion 7 Estimated doses in mSv Living within 50 miles of a nuclear power plant for a year Working as an airline pilot for a year 2.2 Eating a banana0.0001Having a CT scan of the head 2.3 Having a dental x-ray0.005Living in Buxton for a year3.1 Working in a nuclear power station for a year 0.18PET scan of the head5 Going to Cornwall on holiday for a fortnight 0.3Standing in the grounds of Chernobyl for an hour 6

Buxton & District Science Discussion 8 History 1895X-raysRöntgen 1895RadioactivityBecquerel 1898RadiumCuries

Buxton & District Science Discussion 9 Recognition of use in Medicine

Buxton & District Science Discussion 10 The pioneering days Some conditions recommended for treatment with radium in 1906 Lupus vulgaris Eczema Acne Psoriasis Pain Arthritis Infectious diseases x-rays Radium

Buxton & District Science Discussion 11 Radium dial painters

Buxton & District Science Discussion 12 Legislation 1960Radioactive Substances Act (Updated in 1993) Keeping, storage, disposal of waste 1978The Medicines (Administration of Radioactive Substances) Regulations Administration of radioactivity to patients 1985Ionising Radiation Regulations (Updated in 1999) Work 2001Ionising Radiations (Medical Exposures) Regulations Medical exposures 2001Radiation (Emergency Preparedness and Public Information) Regulations Emergency Preparedness 2004Justification of Practices involving Ionising Radiations Justification

Buxton & District Science Discussion 13 Radiation Dose Internal : from unsealed radioactive substances Modes of exposure to ionising radiation External : from x-rays & sealed radioactive substances

Buxton & District Science Discussion 14 Protecting yourself from ionising radiation Time Distance Shielding And, to reduce internal irradiation you need Good housekeeping

Buxton & District Science Discussion 15

Buxton & District Science Discussion 16 Radiation can only cause harm if at least some of its energy is absorbed within the body

Type of radiationOutside the bodyInside the body Alpha Stopped by thin sheet of paper Imparts all its energy to a tiny area Beta Stopped by a few mm aluminium Almost all of the energy is absorbed close to the site Gamma (sim. X-ray) Shielding needs may be substantial depending on energy A sizeable proportion may escape the body, depending on energy

Buxton & District Science Discussion 18 What sort of damage can radiation do to humans? Acute effects (Radiation sickness) Skin reddening, cataracts (Tissue reactions) Increased probability of certain kinds of cancer – avoidance is main aim of radiation protection (Stochastic effects)

Buxton & District Science Discussion 19 There is hard evidence for radiation sickness and the so-called tissue reactions (were called deterministic and, before that, non-stochastic)

Buxton & District Science Discussion 20 Stochastic effect – Increased probability of cancer Overall, it is estimated that more than one in three people will be diagnosed with some form of cancer during their lifetime.

Buxton & District Science Discussion 21 At 200 mSv, we have reasonably good evidence that death from cancer as a result of radiation exposure is under 9000 in a million to add to underlying incidence of 250,000

Buxton & District Science Discussion 22 Linear No Threshold Model 0 Dose (mSv) Relative increase in risk Linear-No-Threshold (LNT) Supralinear Sublinear Threshold Hormesis Relative benefit

Buxton & District Science Discussion 23 Units of effective radiation dose Rem/Sievert (1 Sievert = 100 Rem) Whole body or part

Buxton & District Science Discussion 24 Rolf Maximilian Sievert Doses talked about so far are whole body effective dose. This is the energy absorbed per mass taking into account the type of radiation and the part of the body irradiated – a measure of harm

Buxton & District Science Discussion 25 There are many assumptions that go into effective dose estimations 1.Energy deposited per unit mass – accurate measure 2.What kind of radiation – α particles are 20 times more damaging than x or γ 3.Which part of the body – gonads more sensitive, liver less so

Buxton & District Science Discussion 26 Tissue weighting factors Gonads0.20Red bone marrow 0.12Colon0.12 Lungs0.12Stomach0.12Bladder0.05 Breast0.05Liver0.05Oesophagus0.05 Thyroid0.05Skin0.01Bone surfaces0.01

Buxton & District Science Discussion 27 Be wary of mSv estimates

Buxton & District Science Discussion 28 Average annual doses

Buxton & District Science Discussion 29

Buxton & District Science Discussion 30 Radon Map

Buxton & District Science Discussion 31 Detailed Radon Map

Buxton & District Science Discussion 32 The Uranium decay chain

Buxton & District Science Discussion 33 The basic assumption behind all the radiation protection precautions we take these days is that all radiation is harmful. Even if it is naturally- occurring like Radon, we seek to limit it as far as possible.

Buxton & District Science Discussion 34 Control of exposure is based on 3 tenets 1. Justification (Risk v Benefit) 2. Optimisation 3. Limits (but ALARP) ALARP = as low as reasonably practicable

Buxton & District Science Discussion 35 Referral guidelines

Buxton & District Science Discussion 36 Data from the NRPB – National Radiological Protection Board (which became part of the HPA - Health Protection Agency and is now, from April 2013, part of Public Health England)

Buxton & District Science Discussion 37 Annual dose limits Classified workers (must be over 18)20 mSv Unclassified workers and trainees6 mSv All others (including members of the public*) 1 mSv * There are no specified limits for patients or ‘carers’

Buxton & District Science Discussion 38 Why does the radiographer go behind a lead screen when an x-ray is taken? It must be dangerous so why isn’t it dangerous for me as the patient ? It’s true of course - the patient will get more dose than the member of staff for that one exposure But the member of staff will be present at many such exposures over the year and the only benefit they receive is that it is their job. There is no justification for irradiation of the member of staff when it can be avoided by standing behind a lead screen.

Buxton & District Science Discussion 39 Ex-Russian agent Alexander Litvinenko died in a London hospital on 23 November 2006 from poisoning with Polonium 210

Buxton & District Science Discussion 40 Polonium 210 absorbed into the body cannot be detected from the outside – the way to check for it is to monitor the urine

Buxton & District Science Discussion 41

The Radioactive Boy Scout David Hahn was 17 when he built a nuclear breeder reactor in his mother’s backyard.