Whitfield Clinic
UPMC Whitfield Cancer Centre | Whitfield Clinic
UPMC Bedford Memorial

Positron Emission Tomography/
Computed Tomography (PET/CT)

What is PET/CT?
How does PET/CT work?
What are the risks and benefits of this therapy?


What is PET/CT?

Positron emission tomography (PET) scans the body to create an image of biochemical activity, highlighting abnormal cells such as those in tumours. A computed tomography (CT) scan shows a very detailed cross-section of the body’s organs, bones, and tissues using computers and x-rays.

Combining the disease-finding properties of a PET scan with the anatomical detail of a CT scan helps your doctor to see cancerous activity more precisely at the cellular level. With this knowledge, diagnoses and biopsies may be carried out earlier and treatment plans may begin much sooner.

Doctors, oncologists, and radiation therapists use PET/CT scanning to look for and locate cancerous tumours, help plan surgical cancer therapy, help plan radiation cancer therapy, such as intensity modulated radiation therapy (IMRT), and follow up on tumour activity after treatment,

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How does PET/CT work?
During the procedure, you will lie still on a special bed while the positron emission tomography/computed tomography (PET/CT) scan takes place. Both the PET scan and the CT scan are performed during one procedure.

In preparation for the PET portion of the scan, a nurse or technologist will first administer a mildly radioactive substance, called a radiotracer, into your bloodstream by intravenous (IV) injection. The radiotracer travels through the blood to the area of the body under study. After receiving the injection you'll lie still for about an hour while the radiotracer is taken up by the tissues.

To enhance the CT portion of the scan, you'll also receive a substance, called contrast dye, either orally and/or by IV. The contrast dye helps certain body organs show up better on the CT scan image.

For the actual procedure you will lie on a bed that will be moved into the PET/CT scanner, a machine that looks like a large doughnut standing on its side. The scanner detects and records the energy levels emitted from the radioactive substance injected into your body, and the images are viewed on a nearby computer monitor. A very detailed x-ray image is also generated of your organs, bones, and tissues being examined. The actual scan takes about 30 to 45 minutes, but the whole procedure will take about two hours.

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What are the risks and benefits of this therapy?
Except for any discomfort associated with the injections, a PET/CT scan is a painless procedure, and requires no anesthesia or inpatient hospital care. Improved benefits of PET/CT scanning for patients include:

  • reduced scanning time
  • improved tumour detection
  • better assessment of response to therapy
  • improvement of therapy planning
  • more precise staging of the disease

The combination of the PET and CT scanning technologies has improved diagnoses of a variety of cancers, including lung, head and neck, ovarian, and cervical cancers.

The most common complications from this procedure are mild symptoms from the contrast dye, including feeling flushed, a few minutes of nausea, or a taste of metal or salt in your mouth. There is a much less likely chance of an allergic reaction to the radiotracer. You should be sure to tell your technologist if you experience any of these symptoms during the procedure.

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