Cancer Research UK on Google+ Cancer Research UK on Facebook Cancer Research UK on Twitter

Does radiotherapy make you radioactive?

This page tells you about whether radiotherapy makes you radioactive. There is information about the 3 main types of radiotherapy


External radiotherapy

External radiotherapy does not make you radioactive. It involves aiming X-rays or radioactive particles at the tumour from outside the body using a special treatment machine. Treatments usually last around 5 to 10 minutes and are given as an outpatient. Some treatments may involve a single dose or fraction. 

For radiotherapy to control symptoms, you may have between 1 and 5 treatments. For radiotherapy that is designed to cure your cancer, you will have a course of daily treatments – usually between 5 and 36 treatments over 1 to 7 weeks. For further information see the page about external radiotherapy.



Brachytherapy is a type of internal radiotherapy. Radioactive tubes, wires or seeds are put into the tumour to give a very intense dose to the cancer and its immediate surroundings.

This type of treatment is used for a variety of tumours, in particular cancer of the cervix. But also some other tumour sites, including the breast. It does make you radioactive whilst the tubes or wires are inside you and will almost always be given as an inpatient.

While you are having treatments of this type there may be restrictions on your visitors, in particular children and pregnant women. These restrictions will be explained in detail by the staff on the ward. Once you have the tubes removed, the radioactivity disappears. For further information see our section about internal radiotherapy.

Brachytherapy is becoming more widely used for prostate cancer. For this treatment, you have radioactive seeds put into the tumour. The seeds stay in place permanently. They gradually lose their radioactivity and are so small that they don't cause any problems if they are left in the prostate. There is detailed information about brachytherapy in the prostate cancer section.


Radioactive injections or drinks

Certain tumours, particularly those of the thyroid, blood and prostate and certain rare childhood cancers may be treated with radioactive liquids that you have as an injection or in a drink.

Some types of thyroid cancer can be treated with a drink or capsule of radioactive iodine. This seeks out any thyroid cancer cells in the body and destroys them. You may have this type of treatment after surgery for thyroid cancer and are radioactive for a few days. So you need to stay in hospital during that time. You may have to follow certain restrictions even when you go home from hospital. The medical staff looking after you will explain these in detail before you go home. But usually, you won't go home until the radiation levels are so low that it is no danger to anyone.

There are two different types of radioactive injections that can be used to treat cancer. Radioactive phosphorus (P32) is used to treat a blood disorder called polycythaemia rubra vera, where the bone marrow produces too many red blood cells. Radioactive strontium injection is used to treat cancer that has spread to the bones, for example from a prostate cancer. These treatments do make you very slightly radioactive for a while but the dose is so low that you are not a danger to anyone.

For further information about the different types of internal radiotherapy see the types of internal radiotherapy section.

Rate this page:
Submit rating
Rate this page
Rate this page for no comments box
Please enter feedback to continue submitting
Send feedback
Question about cancer? Contact our information nurse team

No Error

Updated: 10 July 2012