Not that kind of pet.... the other kind of PET!
After a diagnosis of cancer you will need to have a number of assessments and investigations, one of which may be a PET scan. This might be done alongside a CT scan or at another appointment and you might be asked to have numerous PET scans throughout your treatment period. The PET scan provides the team with a 3 dimensional picture of the inside of your body, which can show a number of things:
- Where the cancer is within your body
- If it has spread
- The size of the cancer
- If the cancer has grown or shrunk
- How well treatment is working
What does a PET scanner look like?
I think some people imagine it to be like a dark tunnel where they might feel claustrophobic but it's more like a large doughnut that you slowly move in and out of. It's not noisy and the most you will probably hear is a slight whirring. But there's nothing that should make you anxious and I actually fell asleep during mine.
Prior to the assessment
You should get a leaflet telling you the dos and don’ts so be sure to read this. Generally, you shouldn’t eat for around 8 hours before the scan (so scans that are first thing in the morning are better). In terms of drinking I was asked to drink two pints of water 1-2 hours before the appointment and I was asked to empty my bladder before the scan. It’s recommend that you don’t exercise for 24-48 hours prior to your scan taking place.
What happens during the assessment?
If you’re wearing clothing with metal accessories (buttons, zips etc.) you will be asked to change into a hospital gown. If you don’t want a hospital gown then take PJ’s or loose gym gear to change into. You’ll also be asked to remove any metal jewellery and piercings.
Before the scan takes place you will have a cannula inserted, be injected with a low-level radioactive tracer solution that contains glucose and then asked to lie still for around an hour so that it can be fully absorbed throughout the body. To minimise movement I was told to not use my mobile phone so ensure you have a book or music to entertain yourself. The reason for this is that cancer cells act very differently to other cells within the body and are more active when growing and reproducing. Because of this increase in activity they require energy so the body will automatically send the glucose solution (containing the radioactive tracer) to these cells. If you increase your physical activity then the body will also send the glucose to feed the muscles altering the results of the scan. The radioactive tracer will then show up as bright or ‘glowing’ spots on the scan, enabling the staff to see where the cancer is within your body.
Once you’ve had your hour of laying down you will then be asked to go through for your scan, which takes between 30-60 minutes (my full body scan took 30 mins). For the scan you will be taken to the scanning room where the radiographer will ask you to lie down and then leave you in the scanning room, there is an intercom system where you will still be able to communicate with the radiographer. Once the scan starts you will slowly move in and out of the doughnut shaped scanner whilst it takes pictures to generate a 3D image of you.
After the scan
Once the scan is complete the radiographer will remove the cannula and you will be asked to get dressed again and are free to go home. You can then eat and drink normally. The radiation in the radioactive tracer is very small and you will more than likely have no side effects from this. Drinking plenty of fluids after your scan helps to flush the radioactive tracer out of your system. As a precaution, you are asked to not have any close contact with children and pregnant women for six hours after the scan has taken place. If you have had and sedative medication to help you relax then you need someone to take you home and stay overnight.
If you are travelling abroad within a week of your scan, it may be a good idea to take your appointment letter with you to show that you have had a scan as most airports have sensitive radiation monitors which may pick up the trace of radiation following your test.
You will be invited back within one to two weeks to discuss your results with the doctor and Macmillan nurse.
Possible risks
A PET scan is a safe test for most people. But like all medical tests it has some risks. Your doctor and radiographer make sure the benefits of having the test outweigh these risks.
Pregnancy
Pregnant women should only have the scan in an emergency. There’s a risk that the radiation could harm the developing baby. Contact the department beforehand if you're or think you might be pregnant.
Breastfeeding
If you're breastfeeding, let the department know a few days before your appointment. They will let you know if you need to stop breastfeeding for a length of time after having the radioactive drug. You might need to store enough expressed milk for at least one feed.
Disclaimer: No PETs were harmed during the making of this blog!!
