What is the risk?
This section page looks at the risks of medical imaging such as Dental X-rays, X-rays, CT, Nuclear Medicine, PET/CT, DXA, Fluoroscopy, Interventional Radiology and Cardiac Catheter interventions. The risks of MRI and ultrasound are slightly different and not covered here.
This page gives more detail around radiation risks. It is recommended that the 'Types of Imaging' section is viewed before this more detailed information.
The main risk associated with imaging is cancer later in life. Different exams are related to different levels of risk from cancer. Other risks include skin reddening and cataracts later in life. These effects are associated with specific exams and will be discussed with you where they may be an issue. More information on these risks are discussed below.
The exam that is best for you will change depending on the information that is required. Everyone that is involved in your diagnosis and treatment works together to keep the dose and risk as low as possible to get the information that they need.
The risks at the doses involved in medical imaging are so low that scientists aren't sure that they exist. This is because the natural risk of cancer is much higher than the risk from imaging and because so many things affect the risk of cancer.
To be on the safe side we assume that the effects seen at high doses also happen at lower doses but at lower levels.
We use this model to predict levels of risk that we cannot measure. However, we know that the risks cannot be much higher than predicted as then we would be able to measure them.
Below is a diagram that broadly shows the risks for each type of imaging. The bands are wide because risk changes so much depending on the exam and individual exposed. For Fluoroscopy, Interventional Radiology and Cardiac Catheter lab exams the risks will be discussed with your prior to the exam. If you would like these risks expressed in another format you can find this in the Risks in Perspective section.
Figure 1. Diagram of the typical levels of risk associated with each type of exam.
If you would like more risk information you can obtain it at the link below.
Hereditary defects in the children or grandchildren of individuals have not been proven in humans. Potential hereditary defects include malformations, metabolic disorders and immune deficiencies. It is important to note that these effects can only occur if the individual has not yet had their children. The risks are lower than the cancer risks that the individual is exposed to.
However, these effects have been seen in animal populations and the potential risks are displayed below for a selected exam (Taken from UK Health Security Agency data):
Almost all medical treatment or diagnosis are associated with some risk. This includes imaging. However, the benefit to you will be that the images will be used to inform your treatment. You can find out about the risk of imaging here. Sometimes people will need to have repeated medical imaging during their lifetime.
When your referral is received, a healthcare professional will look at the risks and the benefits of the scan. They will review past imaging for any information in a process called justifying. The risk to you will always be minimised regardless of the number of exams that you have had.
The additional risk of cancer due to each exam that you have does not depend on earlier exams. So, if you have a chest x-ray today the additional risk from that x-ray would be the same if you had 10 x-rays in the past or if you had none. Below is a video which explains this in more detail.
Individuals who have repeated head CTs may be at increased risk of cataracts later in life. The imaging specialist who will justify your exam will take this into account.
The risk of erythema (skin burn like sunburn) may be increased if you have multiple long and complex fluoroscopy exams within a short period of time. The staff member justifying your exam will check if this is the case and discuss this risk with you prior to the exam. The alternative to these procedures is usually open surgery which is associated with other risks.
If you are at all concerned about your history of exposure, please discuss this with your doctor.
Take away points
Your referrer and the imaging specialist will work to reduce the risk to you from any exposure.
They will look at any factors which may affect the risk benefit balance for an exam, such as results from previous exams.
This ensures that the risk to you over multiple exposures is minimised as the risk benefit analysis carried out has as much information as possible.
Longer, more complex or higher skin dose exams can lead to skin reddening similar to sunburn.
If you are pregnant, trying to get pregnant or breastfeeding please tell your healthcare professional before having an imaging test.
Contact your healthcare professional to discuss further if you feel anxious.
Some exams may lead to high skin doses that can lead to skin reddening (erythema), like sunburn. This effect is usually limited to long, complex interventional fluoroscopy or cardiology exams. The alternative to these interventions is usually open surgery which lead to other risks.
If you are having an exam which could lead to this effect, you will be informed of the risk prior to exposure. This effect is very rare. If you are exposed again within a short period of time, it may make it more likely that you see any reddening.
Throughout your procedure, the Radiographer and the doctor will be aware of the radiation dose that you are receiving. They will make sure that the dose is as low as possible and should inform you after the exam if they think that you may be at risk of showing skin burn. The skin burn may not appear for a number of weeks. You will be given information on what to do if this happens. However, some simple steps you can take that may ease the burn are:
Apply a moisturiser to the reddened area two times a day. Such as E45 cream.
Take a bath or shower every day if possible, using baby soap or unperfumed soap or unperfumed shower gel.
Pat the area dry with a soft towel, being very gentle with folds of skin, taking care not to rub.
Do not swim if you have visibly red skin.
Do not use a sun bed.
If you are concerned about this effect, please discuss it with your doctor during the consent procedure.
What to discuss with your healthcare provider
Is this really necessary?
What are the risks?
Are there other options?
What happens if I don't do anything?
If you would like more information the Royal College of Obstetricians has produced some helpful guidance on risk and making the best decision for you.
Take away points
The Royal College of Radiologists has provided risk guidance for pregnancy procedures and risk estimates.
Some people like to have detailed numerical information about risks. We have provided a summary of the numerical risks provided by the Royal College of Radiologists here. If you want to put these risks into perspective or see them presented in another format click here. However, if you require more detail or advice please contact your local Radiology department.