While medical radiation accounts for over 95 per cent of the population’s artificial radiation exposure, the occupational risk for dental workers is very low, with good practice.
What do I need to know?
In Australia, medical radiation contributes more than natural background radiation to the population dose. Medical imaging is essential to dental practice – there are more registered x-ray users in dentistry than any other profession.
Dentistry uses two main ionising radiation modalities, x-rays and cone beam computed tomography (CBCT). The standard x-ray bitewing uses very low doses of radiation, with CBCT providing more radiation, but still considerably less than general medical computed tomography (CT) scans. Because the doses are very low, both the patient and occupational risks are very low. Despite the very low doses, good practice should be followed.
A significant issue has been some dentists using CBCT as a routine scanning tool for general dentistry. CBCT should only be used for complex, not routine issues. While the occupational doses are very low and negligible with good practice, unnecessary scans are not justified.
What is the possible exposure?
The only source of exposure for dental workers is from x-rays from diagnostic x-rays and cone beam computed tomography. Once the power to the x-ray tube is turned off, the exposure stops. External exposure in dental practices is very low, and with good practice should remain very low. Internal exposure from x-ray equipment due to inhalation or ingestion risk is not possible.
ARPANSA has been monitoring and reporting on medical exposure for decades, therefore there is a good understanding of occupational exposures. Because most dental workers receive very low exposure it is unusual for dental workers to exceed the public limit of 1 mSv (millisievert) 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.
Most dental 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 and rarely above the member of the public limit of 1 mSv. At current exposures the risks are very low and comparable with the risks of exposure from background and medical radiation exposure.
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 – 1mSv. (See Management of Pregnant Workers Exposed to Ionising Radiation factsheet)