A CT scan produces a series of images that can detect many conditions that are not detectable with conventional x-rays.
CT scans are exams that involve lying on a table while a special x-ray machine produces cross-sectional images or pictures of the inside of the body. During the scan, an x-ray tube producing a thin beam of radiation moves around the area of your body being scanned while the table moves through the scanner. This produces multiple cross-sectional images which can be combined to create 3D images or images along different planes.
Appointments and Referrals
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What to expect
There are two main exam types in the CT: with intravenous (IV) contrast and without IV contrast. Please note: There is always a possibility that you may need IV contrast on the day of your CT exam, regardless of what your referring physician originally requested. Our specialized team will determine the best imaging protocol required for you. Should you have any concerns, our nurse, technologist, and/or radiologist will be happy to assist you on the day of your exam. Please review the following instructions for your CT scan, both for non-contrast and contrast Studies.
For all CT exams, please remove jewelry, hairpins and bobby pins before your exam. No other preparation is needed for CT studies without IV contrast.
For studies without IV contrast, exams are relatively short, usually lasting no longer than 5 minutes.
For studies with IV contrast, exams can be longer, ranging from 5 to 30 minutes, or more. When receiving IV contrast, it is normal to experience a warm sensation and a metallic taste in the mouth. A feeling of mild nausea after the exam is also not uncommon. These effects are short-lived and go away on their own.
For CT exams with IV contrast, please review the following instructions:
- Allergies: If you have a history of allergic reactions to X-ray dye (IV contrast), you should notify your doctor to arrange for pre-medication. Please also inform the technologist and/or nurse prior to your exam. The recommended pre-medication regimen is as follows:
- Prednisone 50 mg – Three (3) doses: 13 hours, 7 hours, and 1 hour prior to scheduled exam time
- Diphenhydramine (i.e. Benadryl) 50 mg – One (1) dose: 1 hour prior to exam time
- Renal Disease: If you have a history of renal disease (i.e. Chronic Kidney Disease, Acute Kidney Injury, Kidney surgery/Nephrectomy/Ablation, or Albuminuria), a Creatinine/eGFR from within 90 days of your appointment is required. Please have your physician order bloodwork to have this arranged for you.
- Duration: Please allow at least 2 to 3 hours for the appointment.
- Food: Do not eat or drink 2 hours prior to your appointment. Medications with small sips of water is okay. Depending on your test, you may be given something to drink prior to your exam.
- Medications: Please take your medications as prescribed, regardless of your appointment time.
- For CT Enterography ONLY (not required for other CT scans): You should only consume clear fluids only for 4 hours prior to examination. You will need to arrive at least 30 minutes to 1 hour prior to your scheduled appointment time. You will need to arrange for someone to take you home. You will need to stay in the department for at least 45 minutes after the scan to be close to the washroom.
If you are pregnant, please tell your doctor. They may recommend another type of exam.
For CT-guided biopsies and procedures, please refer to the Interventional Procedures webpage to learn more about how to prepare for your exam. Your referring specialist physician will provide you with instructions for your specific procedure. If you have not received the instructions from your specialist physician, please call us at 416-469-6580 extension 2310.