Computed Tomography (CT)

What is Computed Tomography (CT)?

CT scanning – sometimes called CAT scanning – is a noninvasive medical test that helps physicians diagnose and treat medical conditions.

CT scanning combines special X-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body.

CT Radiation Dose Reduction

Hoag is working to improve patient safety by optimizing scan parameters that reduce patient dose as much as possible without compromising diagnostic quality. An efficient process has been developed to monitor, manage, and optimize patient radiation dose. Hoag is on track to reduce CT radiation dose for CT procedures by 20%.

What to Expect

CT exams are generally painless, fast and easy. With helical CT, the amount of time that the patient needs to lie still is reduced.

Though the scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes. If you have a hard time staying still, are claustrophobic or have chronic pain, you may find a CT exam to be stressful. The technologist or nurse, under the direction of a physician, may offer you some medication to help you tolerate the CT scanning procedure.

If an intravenous contrast material is used, you will feel a pin prick when the needle is inserted into your vein. You may have a warm, flushed sensation during the injection of the contrast material and a metallic taste in your mouth that lasts for a few minutes. Some patients may experience a sensation like they have to urinate but this subsides quickly.

If the contrast material is swallowed, you may find the taste mildly unpleasant; however, most patients can easily tolerate it. You can expect to experience a sense of abdominal fullness and an increasing need to expel the liquid if your contrast material is given by enema. In this case, be patient, as the mild discomfort will not last long.

How to Prepare

When you schedule your appointment, we will inform you about any specific preparations depending upon the specific procedure your doctor has ordered. Please contact the Scheduling Department at 949/764-5573 if you have any questions.

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure.

If your physician has ordered your CT procedure with radiographic contrast:

  • You should inform your physician if you have any allergies. If you have been told you are allergic to contrast or have ever had a reaction to Iodine or any form of contrast media, your doctor may prescribe medications to reduce the risk of an allergic reaction. A Radiology nurse should contact you. If you have not been contacted by a Radiology nurse at least 24 hours prior to your appointment, please contact the Imaging Scheduler immediately.
  • If you have diabetes, kidney problems, lupus, surgery on your kidneys or multiple myeloma, you must have lab work that includes a BUN and Creatinine performed within 30 days of your exam. If you are over the age of 65, you must have lab work within 90 days of your exam. This provides us with information regarding your current kidney function. Please call your physician if you have not had this blood work.
  • If you are currently receiving Dialysis, please schedule your dialysis to follow your procedure with Contrast or the following day. It is imperative you have dialysis no later than the following day after you have received contrast for your procedure.
  • If you have been diagnosed with diabetes and/or you are currently taking any of the following medications: Metformin, Gluicophage, Glucophage XR, Fortamet, Riomet, Metaglip, Glucovance, Actoplus Met, Avandament or Junamet, stop taking your medication for a total of 48 hours after your exam. You must contact your physician for alternative medications and instructions prior to your exam
  • We encourage you to hydrate with oral fluids at least 24 hours prior to your study. You may have only clear liquids as well as your necessary medications 2 hours before your exam.

You may receive additional specific instructions when you schedule your appointment depending upon the type of procedure that will be performed. Some types of scans require fasting beforehand. Please complete, print out and bring the following forms to your appointment:

Outpatient Medication Reconciliation - Download PDF
CT Outpatient Questionnaire - Download PDF


Locations where Hoag provides CT scan services