Radiation doses received during medical procedures

Some medical procedures involve the use of radiation.

For example:

imaging scans like CT scans, x-rays, mammograms
nuclear medicine scan
radiotherapy

Ultrasound and MRI scans do not use radiation. They use radio-waves and magnetic fields.

Always tell your doctor about any procedures you’ve had that involved radiation.

They will take this into account when deciding on the best options for you.

Risks associated with radiation

There can be a risk of cancer associated with exposure to radiation. Most of the time, the risk is low to moderate. The risk increases the more procedures involving radiation you have over your lifetime.

Levels of risk

The level of risk depends on the:

type of procedure and dose of radiation you get
area of the body exposed to radiation
length of time you are exposed to radiation

For example:

a CT scan of the chest, abdomen or pelvis will deliver a lot more radiation (and carry more risk) than an x-ray of a hip
a nuclear medicine scan may mean you are radioactive for at least 24 hours - there is a risk of exposing people around you to radiation during this time
the amount of radiation used in cardiac procedures varies depending on the type of procedure and how long it takes

Doses of radiation in common procedures

In medical imaging procedures, radiation dose is usually measured in millisieverts (mSv).

You can see the millisieverts for different types of common procedures involving radiation below.

To get more detailed information on the radiation dose you received, you can:

contact the department where you had your procedure
ask the doctor who referred you to request this information

X-ray, mammogram, DEXA

One x-ray, mammogram, or DEXA (bone density scan) has a very low dose of radiation.

They all use a radiation dose of less than 1 mSv.

There is almost no risk.

CT scans

The risks associated with a CT scan will vary depending on the radiation dose used. The dose used depends on the area of the body involved and the type of CT that’s done.

Here are some examples to help explain this.

Head, chest or abdomen CT scan

CT scans of the head, chest or abdomen involve a radiation dose of less than 10 mSv.

The radiation risk is minimal to very low.

CT-TAP and PET-CT scans

A CT-TAP scan is a scan of the thorax, abdomen and pelvis. A PET-CT scan shows how your body's cells are working. They both involve a radiation dose of more than 10 mSv.

The radiation risk is low.

Nuclear medicine

If you have a nuclear medicine scan, your radiation risk is low.

But you should minimise your contact with other people. This is because you may be radioactive for at least 24 hours so you could expose people near you to radiation.

It is important to follow the advice you get when going home from the hospital.

Interventional radiology

The risk associated with interventional radiology procedures varies but it is low to moderate.

The level of risk depends on:

the area of body exposed to radiation
the type of procedure performed
how long the procedure took

Interventional cardiology

The risk associated with interventional cardiology procedures varies.

The radiation risk is low to moderate.

The level of risk depends on the:

the type of procedure performed
how long the procedure took

Radiotherapy

The aim of radiotherapy treatment is to deliver as much radiation as possible to kill the diseased tissue while limiting the damage to healthy tissue.

Radiotherapy treatment is different for every patient. The radiation dose you get depends on the type of cancer you have and where you have it. Your radiotherapy team will explain how many radiation doses you will get.

Your radiation oncologist prescribes the radiotherapy dose. Treatment is usually given over the course of several sessions for a set time. In some cases, a single radiation dose is prescribed. You may also need diagnostic imaging procedures such as CT scans or x-rays. This will be part of your radiotherapy care plan.

The lifetime risks associated with radiotherapy treatment will vary. Talk to your radiotherapy team for more information.