Scans

You’ve just received a letter explaining you need a scan. There are many types of medical scans that are used to view different things. Here we explain the common scans you may have during your cancer journey.

Browse the whole webpage or click on the images below to find out more about a certain scan. 

X-Ray 

These scans are quick and painless and use radiation to view structures within the body. The radiation passes through soft structures and is absorbed by harder structures (e.g. bones). The radiation that passes through the body is measured by a detector and creates the final image. It is particularly good at visualising harder structures but the images are not very detailed.

X-rays involve small doses of radiation equivalent to anywhere between a few days and few years of normal background radiation. During the procedure, the body part being scanned will be positioned against the radiation detector with the X-ray machine opposite. The scan will only take a couple of minutes and if done as an outpatient you can usually go home immediately.  

CT Scan  

CT scans (CAT scans) involve multiple x-rays from different angles which create very detailed images of the inside of the body. They are painless and used to diagnose, monitor, and guide treatment in a number of different conditions.

The amount of radiation used in CT scans is equivalent to anywhere between a few months and few years of normal background radiation. During the scan you will be lying on a bed and moved through the scanner which looks like a giant donut (you will never be completely enclosed by the scanner and always be able to speak to someone). The scan normally lasts between 10-20 minutes depending on the part of the body being scanned. Sometimes, to get an even clearer picture of what is going on you will be given a dye (known as contrast). Depending on the reason for the scan the dye can be given as a drink, injected into a blood vessel or given as an enema (capsule put into the back passage). If you have a CT scan as an outpatient, you can usually go home immediately after but may be asked to wait for 30 minutes to an hour if you have had the dye as in rare cases (1 in 1000 people) it can cause an allergic reaction.

MRI Scan

An MRI scan is a painless procedure which uses magnetic fields and radio waves to create images of the body (no radiation is involved). Similar to CT scans, the images produced are very detailed, however MRI scans are particularly good at visualising softer structures (e.g. the brain).  The images can help to diagnose, monitor and manage a condition.

During an MRI scan you will be put on a bed and moved into the scanner either feet or head first depending on the scan.  The scanner is a long tube, which some people do find claustrophobic but you will always be able to communicate with someone while inside. They also are very noisy and you will be given earbuds or headphones to wear during the scan; In some cases, you can choose your own music to listen to. If you have concerns about this, talk to your medical team as sometimes they can provide a light sedative. MRI scans range in length depending on the area being scanned and usually last between 20 minutes to an hour. Sometimes, to get an even clearer picture of what is going on you will be given a dye (known as contrast). The dye can be given as a drink, injected into a blood vessel or given as an enema (capsule put into the back passage). If you have an MRI scan as an outpatient, you can usually go home immediately after but may be asked to wait for 30 minutes to an hour if you have had the dye as in rare cases (1 in 1000 people) it can cause an allergic reaction.

PET Scan

A PET (positron emission tomography) scan is a painless procedure used to visualise cellular activity in your body. It is often used to investigate and monitor confirmed cases of cancer. The scan involves being injected with a substance which emits radiation (this is known as radiotracer). This substance acts similarly to glucose, the molecule that provides us with energy, which will build up in areas using a lot of energy. CancerA disease where cells divide and grow uncontrollably and can spread to other areas of the body. cells need a lot of energy and therefore the radiotracer accumulates where the cancer is and is interpreted by the PET scanner as an image. The resulting image shows up areas where the radiotracer and therefore active cancer is.

PET scans can also be combined with MRI or CT scans and in most cases involve lying on a flat bed that moves through a cylindrical tube; PET scans usually take between 30 minutes and an hour. After the PET scan you will be mildly radioactive for a few hours so are advised to avoid contact with pregnant women and children. The radiation from a PET scan is equivalent to about 8 years of background radiation.

Ultrasound Scan

An ultrasound is a quick, painless scan which uses sound waves to visualise structures in the body. These scans are most commonly known for being used on pregnant women to have a look at an unborn child. Although the images created from ultrasound are not very detailed, they are useful to visualise structures in real time and as it involves no radiation they are completely safe. They usually take between 15-25 minutes.

Types of ultrasounds

External Ultrasound: This procedure is most commonly performed to view the heart or an unborn child but is also used to visualise other structures in the body. It involves a handheld probe being placed against the skin with a small amount of lubricating gel. An external ultrasound should not be uncomfortable but may feel a bit cold.

Internal Ultrasound: This procedure is used to look closely at reproductive organs. It involves inserting a small ultrasound probe no bigger than a finger into the vagina or back passage. The procedure is not usually painful but can be uncomfortable.