Benefits and risks of medical imaging radiation
Benson Radiology is an accredited medical imaging provider.
We abide by the South Australian Radiation Protection and Control Act and the guidelines of the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).
What is medical imaging radiation?
Medical imaging radiation refers to ionising radiation from x‑rays and gamma rays.
Radiation is naturally occurring and can be found in radioactive substances in our food, water, the air we breathe, in the ground or in building materials.
Medical imaging x‑rays are electrically generated and are only present when the equipment is activated. Having an examination that uses ionising radiation does not make patients radioactive.
Gamma radiation is emitted from the pharmaceutical administered in a nuclear medicine scan. Nuclear medicine patients will be radioactive for a short time.
What is radiation dose?
When the path of an x‑ray is altered by contact with an object, the x‑ray deposits some of its energy to that object (including the human body). This deposit of energy is called a radiation ‘dose’.
What examinations are associated with radiation?
Examinations that use radiation include:
- x‑ray
- CT
- fluoroscopy
- mammography
- bone mineral densitometry (BMD)
- nuclear medicine studies such as PET/SPECT/SPECT CT
Ultrasound and magnetic resonance imaging (MRI) examinations do not use radiation.
Benefits vs risks
The purpose of medical imaging is to provide images of sufficient quality to assist the diagnosis and treatment of medical conditions. In this regard, x‑ray imaging generally offers the advantage of being low risk, non-invasive, fast and accurate.
Risks from medical imaging radiation are difficult to accurately measure and are subject to considerable debate. It is believed the risk of developing cancer is slightly increased if you have been exposed to additional ionising radiation above background levels.
However the increased risk is small, and usually less than the risk of not identifying or treating the medical condition. A very low dose x‑ray, such as a chest x‑ray, has a very small risk. And while CT scans may have higher radiation dose, the risk would still be classified as small.
Deciding to have an imaging procedure involving radiation
Your doctor, in consultation with you, will make an assessment that the benefits of the imaging test outweigh any possible risks of radiation.
Our radiologist or nuclear medicine specialist will also assess the appropriateness of the test. This is done by taking into account the information on your imaging request form together with your medical history.
You should discuss with your referring doctor the benefits of having the study.
Children and radiation
The risks are not the same for all people.
The long term risks of medical radiation are lower for elderly patients in comparison to children or unborn children. Children are more sensitive, as the cells that make up their growing tissues and organs are dividing more rapidly.
Extra care is taken with young or pregnant patients and it is important to limit radiation levels or consider alternative tests.
Putting medical imaging procedures into perspective
The table below compares medical radiation with background radiation and the radiation received from flying in a plane.
It also shows the small increased risk of cancer by having a medical radiation procedure.
| Medical imaging procedure | Equivalent background radiation | Flying time resulting in equivalent radiation | Increased risk of death from cancer (due to radiation from procedure) |
|---|---|---|---|
| Chest x‑ray | 3 days | 7 hours | 1 in 1.3 million |
| Abdomen x‑ray | 3 months | 230 hours | 1 in 36,000 |
| Mammogram | 2 months | 130 hours | 1 in 63,000 |
| CT head | 10 months | 670 hours | 1 in 13,000 |
| CT chest | 3.3 years | 2,700 hours | 1 in 3,100 |
| Bone scan | 1.7 years | 1,300 hours | 1 in 6,300 |
| Barium enema | 3 years | 2,300 hours | 1 in 3,600 |
Please note: in Australia there is a risk that about 3 in 10 people will die of cancer, even if they have never had medical radiation
References
- Mr Anthony Wallace and, Prof Stacy Goergen, ‘Radiation Risk of Medical Imaging During Pregnancy’, The Royal Australian and New Zealand College of Radiologists (2011, January 31)
- The Royal Australian and New Zealand College of Radiologists. (2009, May 1). ‘Plain Radiography/X‑rays.’ Retrieved from Inside Radiology
- Mr Anthony Wallace and, Dr Timothy Cain, ‘Radiation Risk of Medical Imaging for Adults and Children’, The Royal Australian and New Zealand College of Radiologists (2013, December 24)
- Goverment of Western Australia Department of Health. (2011, December). Ionising Radiation (IR) In Diagnostic Imaging. Retrieved from Diagnostic Imaging Pathways — About Imaging: Ionising Radiation
- Goverment of Western Australia Department of Health. (2013, December). Diagnostic Imaging Pathways — Consent To Procedure Or Treatment:
- Radiation and Medical Imaging — Queensland Health