What Is PET-CT?

PET is short for Positron Emission Tomography and is a special subtype of Nuclear Medicine. A PET-CT scan uses radioactive tracers (radiopharmaceuticals) to show detailed pictures of the function of organs and tissues within your body and can be used to detect cancers and infections, among many other things.  


The most common tracer used for PET-CT scans is 18F-FDG (fluorodeoxyglucose) which is a radioactive sugar that shows metabolic activity in the body. The tracer is very unlikely to produce any side effects or make you feel any different. Prior to the scan, we inject the radioactive tracer into a vein in your arm and allow some time for it to accumulate in your body’s cells. The scan is performed usually 45-60 minutes after the injection and usually takes somewhere between 25-40 minutes. The PET-CT scanner looks just like a CT scanner but is a little bit longer and wider. 


When you have a PET-CT scan, sometimes the doctor will like you to have a diagnostic CT scan with or without Iodine Contrast (CT Dye), which helps show the structural changes to the organs and tissues in your body. By combining the PET and the CT scans we create a 3D picture of your entire body in only one exam. 



Things To Know: 

PET-CT procedures are extremely safe and there is no risk to anyone with a history of iodine contrast reactions or renal impairment (we do CT scans WITHOUT dye in these cases). PET-CT scans do carry a risk of radiation. However, the benefits of having the test are usually greater than the risks of not having the test. At Alto Imaging, we have the latest technology PET-CT scanner which allows us to use the lowest amount of radiation possible to perform your scan. The radiation doses are low and comparable to other diagnostic procedures such as standard CT scans and X-rays. 

If your PET-CT scan is for your cancer treatment, it can help by: 

  • Finding the right place for a biopsy 
  • Monitoring your cancer treatment to see if it is working 
  • Checking for new cancer growth after your treatment has finished 
  • Assisting planning for radiation therapy 

At Alto Imaging, our PET Technologists will always explain the procedure to you and discuss any concerns you may have prior to starting your test. 


PET-CT requires some important preparation prior to your scan to make sure everything goes to plan on the day of your test. When making your appointment, one of our receptionists or PET Technologists will discuss this with you but some of the instructions will include: 

  • hour fasting – this includes no chewing gum or lollies 
  • Well hydrated on the day of the test 
  • No strenuous exercise 24 hours prior 

If you are diabetic, there may be extra preparation including ceasing some of your medications or changing the timing of your insulin doses. Our PET Technologists will discuss this with you on a case-by-case basis to optimise your scan results. 


Alto Imaging bulk bills all Medicare eligible PET-CT scans provided they come from a specialist doctor. If your GP or another non-specialist provider has referred you for a PET-CT scan, there will be a gap payment. Certain cancers and inflammatory processes are not covered by Medicare. This means even if you are referred from a specialist, there will also be a gap payment. If you have any queries about the cost of a PET-CT scan or need further clarification, please call our Alto Imaging team – we are happy to answer any of your questions.