Positron Emission Tomography/
Computed Tomography (PET/CT)
does PET/CT work?
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,
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
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.