Computed Tomography (Plain and Contrast study)
- 1.General information
- The Computed Tomography (CT) scan department is located in the basement, adjacent to the x-ray department.
- Please arrive at the time indicated and report to reception.
- Please inform if you are pregnant, as all X-ray and CT studies are to be avoided in pregnancy.
- If you need an ambulance (if coming from NU South) please ask our front desk to arrange this for you.
- 2.What is a CT scan?
It is a special x-ray machine combined with a computer that produces cross-sectional images or “slices” of any part of your body. Unlike a standard “flat” X-ray image, a CT scan shows structures within each slice on a three-dimensional plane. As a result, we can see your entire anatomy.
CT scan is extremely valuable in examining the type and extent of kidney lesions, such as stones or cysts or tumors, distorting the urinary tract.
- 3.Is any preparation required prior to the CT?
If we are doing plain CT, no preparation is required.
But if contrast CT is planned, the radiology department of our hospital will give you an appointment for the procedure. You have to come fasting 4 hours prior to the study. If you have diabetes please inform the department as soon as you receive this appointment so that medication can be avoided if you are coming empty stomach. If you have asthma and you use an inhaler as part of your normal medication please bring this with you to the department.
- 4. How is it done?
You may be asked to change your dress to a hospital gown in a changing room. We recommend that you do not wear jewellery, inner wear during your study.
Radiographer will take you into the scan room and ask you to lie on the CT table and perform your scan.
The CT table moves you very slowly towards the hole in the centre of the scanner. It is not a tunnel. The scanner will then produce the x-ray ‘pictures’. It is fairly simple, fast, easy, and you will not feel anything. An automated voice will tell you “take a deep breath and hold it” at the start of the imaging sequence and “breath normally” when it is over. The duration of breath hold may range from 20 to 25 seconds and you will be told to practice the same before the start of the study. Breath holding will prevent any blurring of the images.
- 5. What is plain and contrast CT?
In plain study no contrast is required. In contrast study, depending on the type of study, oral/rectal/intravenous (I.V.) contrast, one or all the above may be used. Contrast study is always preceded by plain study.
If oral contrast is being used, you will be told to drink certain amount of contrast containing solution. The solution is colorless.
If rectal contrast is being used, the nurse will pass a rubber catheter into your motion passage and required amount of contrast is allowed to flow by gravity. Then the rubber catheter would be removed and you will be told to hold the solution in the rectum till the end of study. Once the study is over, you can pass motions after going to toilet. The oral/rectal contrast will help the radiologist identifying bowel structures from other organs.
You may need to have a small needle put into your arm/hand vein by the nurse in order to inject I.V. contrast fluid. I.V. contrast will intensify the images.
- 6. How long will I be in CT?
If plain CT is planned it should get over in few minutes. But in contrast CT, be prepared to be in the department for approximately one-hour.
- 7. What happens after the scan?
The Radiographer will tell you when the study is over, so that you can change your dress. Unless some intervention has been planned on the same day, immediately after the CT scan, you can consume your regular food.
- 8. Will it be uncomfortable during injection?
The needle may hurt briefly while it goes through skin, but after that, you should not have any pain. It is not uncommon for people to feel a little nausea and/or warmth as the contrast medium flows into the body.
- 9. Are there any risks?
The contrast that is injected for the test is generally very safe. Literally, thousands of people have this injection in CT departments every day around the world. However, with every injection of the contrast medium, there is a small risk of reaction. Some people may develop a rash and a few may get a mild asthma attack. Very rarely some get a severe allergic reaction. The doctors and radiographers are trained to recognize these reactions and to treat them promptly.
- 10. What amount of radiation is received by patient during CT?
In plain X-ray abdomen the exposure is 0.7 mSv (Sv –Sievert).
In plain CT abdomen, the exposure is 8 mSv.
In Contrast CT, the exposure is 10 mSv or in other words, it is like doing 15 abdomen X-rays.
- 11. On whom should a Contrast CT not be done?
Your doctor will ensure that your serum creatinine (blood test to know the function of the kidneys) is normal before recommending this test. If you have borderline kidney function or established kidney failure, I.V. contrast injection should not be done and alternate tests may be recommended. If you are diabetic or have history of contrast allergy, please inform your doctor. However oral/rectal contrast can be given.
- 12. When will you get the results of the test?
The images are uploaded immediately. Depending upon your doctor’s availability, you can consult the doctor at any time after this. Compact disc (CD) of the images will available after 1 hour and is given free at no extra cost. Printed report may take upto 1 working day. If you want print of the images it will take 1 day.
- 13. Are there any further tests required after the CT test?
Sometimes yes, based on the CT findings your doctor may ask for further tests that can help in planning your treatment.