In this presentation, we’re going to be discussing the different types of contrast
media used in examinations of the alimentary canal and some of their advantages and disadvantages.
We’ll also be discussing important preparation tips for exam room setup, patient preparation
nd communication, and radiation protection considerations.
Radiographic demonstration of the alimentary canal requires use of contrast media.
Barium sulfate is most common contrast for the alimentary canal, but water-soluble iodinated
contrast media may also be used.
Iodinated solutions move through the GI tract quicker than barium sulfate, and generally
clears the stomach in 1 to 2 hours.
Iodinated solutions do not adhere as well to intestinal mucosa as does barium sulfate,
but it provides a satisfactory examination of the stomach, duodenum, and large intestine
when barium may be contraindicated.
Its disadvantage is it can become diluted in the small intestine, so clear anatomic
detail cannot be seen of the small intestine, and it does permit a rapid survey there
The use of Barium should be approved by a radiologist if the patient has undergone recent
surgery, and should be avoided if there is a known perforation.
Since Barium is a suspension (meaning it does not dissolve in water), the water it mixes
with can be absorbed by the body, leaving the powder portion behind to firm up like
concrete around the area of perforation.
This can cause irritation and inflammation, along with many other undesirable effects
on the body when it cannot be removed.
Water-soluble media is easily removed by aspiration before or during surgery, and is also readily
absorbed and excreted by kidneys in cases of perforation.
Room should be completely prepared before patient enters.
Adjust equipment controls to the correct settings and have footboard and shoulder supports ready.
Check filming devices and the number of image receptors (IRs) available.
Prepare type and amount of contrast, and make any required documentations like lot numbers
and expiration dates of your contrast media.
Be prepared to document how much contrast was consumed after the procedure.
Make sure your bucky tray is moved out of the way of the fluoroscope before the radiologist
enters the room to begin their portion of the exam.
Before beginning examination, the radiographer should describe the contrast media and administration
method (i.e., taste, enema tip insertion).
Inform the patient that the room will be darkened during the procedure, and discuss the different
bodily position and breathing instructions that the radiologist may be instructing them
to do.
Always introduce the patient and radiologist to each other.
Shield pediatric patients and patients of reproductive age (refer to guidelines on p.
33-34, Volume 1 of Merrill’s).
Do not compromise clinical objectives of examination
Other radiation protection measures include close collimation and optimum technique factors.
One challenge of GI radiography is to eliminate motion.
Techniques to prevent motion will be based on each region.
Peristalsis greatest in stomach and duodenum, but slows in distal part of GI tract.
It’s also affected by body habitus, pathology, use of narcotic pain medicine, body position,
and respiration.
Normal peristaltic activity requires exposure times no longer than 0.2 seconds, but should
never be longer than 0.5 seconds.
Hypermotility requires 0.1 seconds or less, and exposures should be made at the end of
expiration in routine procedures.
Also keep in mind the occupational exposure factors for technologists as well.
This diagram shows the fluoroscopic exposure patterns and their intensity.
Keep the time within these areas limited, and when possible, back away from the patient
to produce distance from scattered radiation (without risking patient safety of course).
And definitely make sure you’re shielding yourself and the patient if the examination
doesn’t prevent you from doing so.
Remember, your job as the technologist during the radiologists fluoroscopic routine is to
ensure patient safety first, but also to assist the patient in obtaining the positions required
for the exam, aiding with contrast administration – whether that requires the patient drinking
or by handling the enema bag for a BE, and maximizing the patient’s comfort level and
modesty – all while practicing radiation safety for those in the exam room.
It takes some practice to do all of these things efficiently and effectively, but developing
this mindset now, will greatly help you throughout your career as a technologist.