While medical radiation accounts for over 95 per cent of the population’s artificial radiation exposure, the occupational risk for medical workers is low, with good practice.
What do I need to know?
In Australia, medical radiation contributes more than natural background radiation to the population dose. With good practice, patient dose does not translate directly to occupational dose. All medical facilities are aware of the potential risks of ionising radiation and assure that exposure is avoided or minimised.
There are two broad areas of medical radiation – imaging and therapy.
Therapy often involves high doses to patients, the occupational doses received by workers is low.
Medical imaging is a vital and powerful diagnostic tool and as such is widely used and responsible for the majority of the population dose. X-rays are the most common imaging procedure, with CT scans the largest contributor to medical dose, as each CT scan is the equivalent of many X-rays.
What is the possible exposure?
The two main sources of exposure for medical workers are X-rays, and unsealed sources. Once the power to the X-ray tube is turned off, or the source of radiation is removed, the exposure stops.
External exposure for medical workers is low, and with good practice should remain low. Internal exposure from X-ray equipment due to inhalation or ingestion risk is not possible. Internal exposure from unsealed sources due to inhalation and ingestion under normal conditions is unlikely.
ARPANSA has been monitoring and reporting on medical exposures for decades, there is a thorough understanding of occupational exposure.
The vast majority of workers in facilities that utilise radiation typically receive no occupational exposure. These include administrative workers, cleaners, most nurses, doctors and other allied health professionals. Of those that do receive an occupational exposure, including some doctors, nurses, radiologists and radiographers, most receive up to or around the public limit – 1 mSv per year. For a small number of activities, including nuclear medicine and cardiology, the annual occupational dose for medical professionals may be around 3 mSv per year.
In comparison average background radiation exposure in Australia is 1.5 mSv per year from natural sources and currently Australians are exposed to an average of 1.7 mSv per year from medical exposures.
What are the possible health effects?
Table 1: Possible health effects
|Dose range (millisieverts)||Description||Possible health effects|
|Up to 10||Very low dose||None observed or expected (typical background range)|
|10–100||Low dose||Plausible health effects but not observed|
|100–1000||Moderate dose||Increase risk of cancer
Acute effects at higher end of range (above 500 mSv)
|Above 1000||High dose||Acute effects (burns, vomiting)
Death possible at very high doses (above 5000 mSv)
No health effects have been observed or are expected to be observed at the very low doses normally received in this occupation.
Ionising radiation has been proven to cause harmful short term effects at moderate and high doses received in short periods of time, above 500 mSv, with an increased risk of cancer shown to occur for long term exposures of above 100 mSv.
Most medical workers receive no occupational dose and those that do typically receive a very low dose that is a small fraction of the occupational dose limits. Despite this, it is good practice to avoid or limit occupational dose where possible. Some activities (e.g. cardiology or interventional radiology) may involve exposure to the eye at dose levels where cataracts may be of concern. Appropriate eye protection will limit the exposure to ionising radiation.
Who is responsible for your safety?
In Australia the use of irradiating apparatus and radiation sources is regulated. Each state and territory is responsible for enforcing their respective radiation safety act and regulations in their jurisdictions. The Australian government is responsible of enforcing the radiation safety act and regulations of commonwealth entities only.
Organisations/employers are responsible for:
- devising, implementing, and regularly reviewing their radiation management plan
- regulatory compliance
- induction and ongoing training of workers, including contractors.
Workers are responsible for:
- following radiation protection practices specified in the radiation management plan
- complying with legitimate instructions of the employer or designated radiation safety officer
- participate in radiation protection training.
What are dose limits?
All Australian jurisdictions have uniform annual limits for public and occupational exposure to ionising radiation: 1 mSv for the public and 20 mSv for workers who are occupationally exposed. Despite this, there are different definitions of who is ‘occupationally exposed’ and who should wear personal dosimeters. You can further discuss occupational radiation exposure with your facility’s Radiation Safety Officer or the relevant jurisdictional regulator.
For a pregnant radiation worker, the dose to the unborn child is restricted to the same as a member of the public – 1 mSv. (See Management of Pregnant Workers Exposed to Ionising Radiation Factsheet)