Barndioota consultative committee meeting

Radiation – What is it? All living things rely on some form of radiation for their existence Radiation is all around us all day, every day It is the energy carried by either electromagnetic waves or moving particles

The electromagnetic spectrum Cosmic rays from the sun have higher energies than gamma rays Radiation may be non-ionising or ionising The non-ionising radiation takes in the lower energies on the spectrum

Ionising radiation Can produce charged particles in matter Includes: Cosmic rays Gamma rays X-rays Alpha radiation Beta radiation Neutrons We are surrounded by naturally occurring ionising radiation. This is called background radiation.

Background radiation Where does it come from?

How is radiation measured? Radiation can be measured in a number of different units The most common is the Sievert (Sv) 1 Sv is a very large amount so usually the milliSievert (mSv) is used 1 Sv = 1000 mSv Average background radiation in Australia is about 2mSv per year Limits for people who work with radiation in Australia are 20mSv per year Doses below 50mSv are regarded as low dose

Average annual doses from natural radiation sources On a global scale it can be seen that Australia’s background radiation is relatively low

Radiation from medical procedures Source Typical Dose (mSv) Equivalent period of natural background radiation Chest X-ray Dental X-ray 0.02 0.005 5 days 1.25 days CT scans – head – chest – abdomen 2.6 8.0 13.0 1.7 years 5.3 years 8.7 years Barium meal 2.5 1.6 years Mammogram 0.4 13 weeks Nuclear medicine scans – bone scan – thyroid – liver 4.6 1.7 3.0 years 1.1 years Note re nuclear medicine scans – it is worth pointing out to people that the benefit of having the scan far outweighs the risk from the increased exposure.

Radiation exposure and flying Ionising radiation levels are higher in a flying plane than levels on the ground At cruising altitudes exposure is greater than on the ground Annual exposure to aircrew on domestic flights is around 1.8mSv above background Aircrew on international flight routes receive around 4mSv extra per year

Radiation – alpha, beta, gamma Type What is it made of? Reason the atom was radioactive  alpha α helium nucleus Too large  beta β e- Too many neutrons e+ Not enough neutrons  gamma γ high energy wave Too much energy

Penetration of radiation Alpha particles Beta particles Gamma rays PAPER ALUMINIUM LEAD

Measuring the lifetime of a radioactive substance Half-life Measuring the lifetime of a radioactive substance The time required for half of a given amount of a radioactive substance to decay At start After 1 half-life After 2 half-lives After 3 half-lives

Monitoring radiation levels in the workplace All workers in a radiation environment wear these, or similar, devices to monitor their exposure

An important nuclear medicine When we split uranium we make a smaller atom called molydenum-99. This is radioactive and can be used as a medicine. How it works is we put the molybdenum in this pot here (pick up Gentech and point to vial) and send one of these to 250 hospitals around Australia each week. In the hospital the doctor will get the medicine out of the pot by pouring in some slightly salty water. The water which contains the medicine is then injected into the patient. They then have to lie really really still and go inside one of these big machines called a SPECT scanner. What happens is that the medicine then breaks down, because it is radioactive and releases some radiation. The radiation is then picked up with a special camera called a gamma camera and colourful pictures of the body like these are made. This top picture shows inside a person’s brain and the bottom picture shows inside a person’s head and chest. The doctor can look at these these pictures and see if there is something wrong with that person’s body. For example, if a person has a cancer lump somewhere the doctor will see it on the scan. Also, if there is something wrong with the brain or heart or lungs or bones the doctor will be able to see this too.

Thank you