Planning external radiotherapy

The radiotherapy team plan your external beam radiotherapy before you start treatment for cervical cancer.

This means working out the dose of radiotherapy you need and exactly where you need it. Your planning appointment takes from 15 minutes to 2 hours.

You usually have a planning CT scan in the radiotherapy department.

The scan shows the cancer and the area around it. You might have other types of scans or x-rays to help your treatment team plan your radiotherapy. The plan they create is just for you.

Photo of a CT scanner

The therapy radiographers will explain the procedure in detail at the beginning of your planning appointment. They will tell you what will happen.

Before the scan

Before your scan you might need to drink a few cups of water. You will also need to drink before your treatment sessions. This is so that you have a full bladder, which is roughly the same size and in the same position every day. You may also need to have an empty bowel.

Your radiographer or doctor might put a little marker inside the top of your vagina. The marker is usually a little piece of metal. This shows the position of the vagina clearly on the scan. The marker is taken out after the scan has finished.

You might have an injection of contrast medium (a type of dye) through a small thin tube (cannula) in your arm. This can:

  • make you feel hot and flushed for a minute or two
  • give you a metallic taste in your mouth
  • make you feel like you’re passing urine but you aren’t – this feeling is common and passes quickly

The radiographers help you to get into position on the CT couch. They might put a firm cushion around you to help you keep still. You need to stay in this position for a little while so let the radiographers know if you are uncomfortable.

Having the scan

The radiographers move the couch up and through the scanner and then leave the room. The scan starts and takes about 5 minutes. You won't feel anything.

You need to lie very still. The radiographers watch from the next room.

Before the planning appointment you might also have other scans, such as an MRI scan.

After your scan

You stay in the department for about 15 to 30 minutes if you had an injection of the dye. This is in case it makes you feel unwell, which is rare.

The radiographer removes the tube from the vein in your arm before you go home. You should be able to go home or back to work. You can eat and drink normally.  

Possible risks

A CT scan is a safe test for most people but like all medical tests it has some possible risks. Your doctor and radiographer make sure the benefits of having the test outweigh these risks.

Allergic reaction

Rarely, people have an allergic reaction to the contrast medium. This most often starts with weakness, sweating and difficulty breathing. Tell your radiographer immediately if you feel unwell so they can give you medicine.

Contrast medium

There is a risk that the contrast medium will leak outside the vein. This can cause swelling and pain in your arm but it’s rare.

Ink and tattoo marks

The radiographers make pin point sized tattoo marks on your skin. They use these marks to line you up into the same position every day. The tattoos make sure they treat exactly the same area for all of your treatments. They may also draw marks around the tattoos with a permanent ink pen, so that they are clear to see when the lights are low.

Photograph of radiotherapy tattoo marks

The radiotherapy staff tell you how to look after the markings. The pen marks might start to rub off in time, but the tattoos won’t. Tell your radiographer if that happens. Don't try to redraw them yourself. 

After your planning session

You might have to wait a few days or up to 3 weeks before you start treatment.

During this time the physicists and your radiographer doctor (clinical oncologist) decide the final details of your radiotherapy plan. They make sure that the area of the cancer will receive a high dose and nearby areas receive a low dose. This reduces the side effects you might get during and after treatment. 

Last reviewed: 
31 Mar 2020
Next review due: 
31 Mar 2023
  • Cervical cancer: ESMO clinical practice guidelines for diagnosis, treatment and follow up
    C Marth and others
    Annals of Oncology, 2017. Volume 28, Supplement 4

  • Cancer and its Management (7th edition)
    J Tobias and D Hochhauser
    Wiley Blackwell, 2015

  • Cancer: Principles and Practice of Oncology (11th edition)
    VT DeVita , TS Lawrence, SA Rosenberg
    Wolters Kluwer, 2019

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