NCCN Guidelines for Patients
Colon Cancer, Version 1.2014
Imaging tests allow your doctors to see inside your
body. Pictures (images) are made with scanning
machines. Scanning machines are large and have an
opening in which pictures are taken.
A CT (
omography) scan of the chest,
abdomen, and pelvis is recommended for cancer that
has spread beyond the second layer of the colon wall.
Pictures from these areas will help inform your doctor
if the cancer has spread to nearby or distant sites. Test
results may change the clinical stage of the cancer.
Getting a CT scan is often easy. Before the test,
you may need to stop taking some medicines, stop
eating and drinking for a few hours, and remove
metal objects from your body. A contrast dye should
be used to make the pictures clearer. The dye will be
injected into your vein and you will also need to drink
barium. The contrast may cause you to feel flushed or
get hives. Rarely, serious allergic reactions occur. Tell
your doctor and the technicians if you have had bad
reactions in the past.
During the scan, you will need to lie face up on a
table that moves through the imaging machine.
See Figure 3.2.
A CT scan takes many pictures of
a body part from different angles using x-rays. As
the machine takes pictures, you may hear buzzing,
clicking, or whirring sounds. You will be alone, but a
technician will operate the machine in a nearby room.
He or she will be able to see, hear, and speak with
you at all times. One scan is completed in about 30
seconds. A computer combines all the x-rays to make
You will likely be able to resume your activities right
away unless you took a sedative. You may not learn
of the results for a few days since a radiologist needs
to see the pictures. A radiologist is a doctor who’s an
expert in reading the images.
A PET/CT (
omography) scan is not recommended for most
people. PET/CT should only be used to assess an
unclear finding of a CT scan with contrast. You may
also have a PET/CT scan if you shouldn’t receive
Figure 3.2 CT scan machine
A CT machine is large and has a tunnel in the
middle. During the test, you will lie on a table that
moves slowly through the tunnel.