What Should I Expect for my PET/CT Scan?

June 1, 2017

Patients undergo different types of scanning procedures to produce detailed images of potential cancer growth. Depending on the cancer, physicians may use MRI, mammography, CT, PET/CT or other technologies.

While some of these procedures use only x-rays or radio waves to create images, a PET/CT scan uses a combination of traditional x-rays and computer imaging. A radioactive substance similar to glucose is given to the patient, and because cancer cells tend to use more glucose than normal cells, PET/CT scans can help detect the biological activity of those cancer cells.

The procedure involves a radioactive substance, but it does not have any side effects and is painless. If you have any questions or concerns about an upcoming PET/CT scan, your care team can answer any questions or concerns.

A PET/CT scanner
A PET/CT scanner

Before the PET/CT scan

To produce accurate results, patients need to prepare for a PET/CT scan:

  • Do not wear clothing with snaps, zippers, buckles, or any other large pieces of metal, and do not wear jewelry. These items could potentially interfere with the scanning procedure.
  • Do not eat or drink for six hours before the test and do not suck or chew candy, gum, or lozenges. Plain water, with nothing added, is fine to drink.
  • Try to limit physical activity for 24 hours prior to the exam.
  • Prescribed medications are fine to take prior to the exam.
  • Insulin or oral agents used to control diabetes should not be taken within four hours of the PET/CT scan. Physicians may adjust eating restrictions if the diabetes is diet-controlled.
Technicians Tim Belisle and Tricia Locascio of Nuclear Medicine in the PET/CT control room.
Technicians Tim Belisle and Tricia Locascio of Nuclear Medicine in the PET/CT control room

What to expect on the day of the scan

  • The PET/CT scan appointment takes about two hours total, which includes preparation and scan. The PET/CT scan itself typically lasts 30-60 minutes, depending on the imaging needs.
  • You can bring your own music player and headphones into the procedure room, which also has classical music available to play.
  • You can take prescribed medications such as Valium, Ativan, or other pain medications to reduce anxiety.
  • After you check in, a technologist will explain the PET/CT scan, record your height and weight, and answer any questions. The technologist will also take a small blood sample to test blood glucose levels.
  • Once the blood is checked, the technologist will inject the radioactive substance into a vein. You will need to rest in a reclined position for 60 minutes before the scan.
  • After the PET/CT scan, a radiologist will review the images and send a formal report to the patient’s physician.

For more information on scanning procedures, including other common scans such as MRI, CT, ultrasound and mammography, visit the Dana-Farber Imaging Services website.