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Child and Adolescent Health Service

Services A – Z

 

Princess Margaret Hospital

Diagnostic Imaging

What Is a CT?

How Should I Prepare My Child?

What is a CT?

A CT uses radiation to produce cross sectional images of the body. The main part of the unit is known as the gantry and is circular shaped, with an x-ray tube that rotates directly opposite a row of detectors. These images may be combined to provide a volume of information. This can be used to create images in multiple planes, resulting in three dimensional reconstructions of parts of the body.

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What Do I Do Before the Test?

Some CT examinations do not require any preparation. Preparation is necessary where oral and/or intravenous contrasts are required. When possible, intravenous contrast requires a three hour fast from solids and a two hour fast from all fluids. This precaution is taken to reduce the chance of the patient becoming nauseous after receiving the contrast.

Intravenous contrast is injected into the blood stream. It is a dense clear liquid that helps to highlight blood vessels and demonstrate blood perfusion. Oral contrast is either drunk by the patient or administered through a nasogastric tube. It is designed to delineate the bowel from other structures.

Oral contrast is given to the majority of patients requiring an abdominal CT. The contrast comprises of 9.5mls of gastroview mixed in with 375mls of a soft drink, orange juice or water. It is required to be drunk up to two hours prior to the examination, with the timing dependant upon the patient’s clinical history.

Preparation is also necessary when the patient requires an anaesthetic in order for the procedure to be completed. In this situation, standard fasting requirements are to be observed.

The exact preparation required for your child’s examination will be explained to you at the time of the booking. If you are unsure or need further information, please do not hesitate to contact the department prior to the examination.

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Will I Need to Give Consent?

Prior to the CT taking place, the parents or patient (depending on age) will be required to read and sign a checklist granting permission for the CT scan and the use of IV Contrast. The consent form details the risks involved with radiation exposure and IV contrast.

If the patient requires the administration of intravenous contrast, there is another consent form for this. This consent involves answering a number of questions regarding the patient’s medical history, in order to distinguish whether they may have an allergy to the contrast medium.

If you require a copy of either consent form, please click the links below.

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How are the Pictures Taken? image of ct room - click to enlarge

The patient will be asked to lie on a table that moves up and into the camera. The camera does not touch the patient but can be seen to rotate around within the gantry. When the pictures are being taken the table will move in and out of the gantry. An initial picture is taken that then allows the radiographer to plan the main series of images.

Between series, the intravenous contrast may be administered. In some cases (for example, when imaging the chest) it is necessary for the patient to hold their breath. Breathing instructions are given to the patient to let them know when they need to hold their breath and when they can breathe again.

The most important thing that patients need to remember when they are having a CT scan is that it is necessary for them to keep very still. Any movement while the scan is actually taking place will cause blurriness, and the pictures

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Who Looks at the Pictures?

A paediatric radiologist (a doctor specially trained in children’s imaging) looks at the pictures and sends a report to your child’s doctor.

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What Happens After the Test?

The radiographer will let you know when your child can leave.

After the test your child can eat and drink normally, unless your child’s doctor has told you otherwise.

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When Do I Get the Results?

The radiologist will review the pictures and send a report to your child’s doctor. If there is a serious problem that requires treatment your child’s doctor will be notified before you leave the department.

The results will be available at the next outpatient clinic appointment or with your GP depending on who referred you to the department.

In some cases, the requesting doctor will ask you to return immediately after the scan to see them. They will contact the radiologist at the time in order to get a result.

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How Should I Prepare My Child?

Infants

Even though the test cannot be explained to your baby you can make them feel more secure if you:

  • Bring along a special blanket, toy or dummy.
  • Talk to your child during the test.
  • If your child is very young, we may ask you to feed your baby just prior to the scan, in order to settle them down and encourage them to fall asleep. This may then negate the need to give your child an anaesthetic.

Toddlers and Preschool Age

  • Explain the test to your child just beforehand as they may become anxious if told too far in advance.
  • On the day of the test tell your child they will be having some pictures taken and you will stay with them during the test.
  • Bring a favorite toy or book and a snack for afterwards.

School Age

Explain to your child in simple language that they are going to the hospital to have some pictures taken of his/her body and that you will stay with them during the test. Bring along a snack for after the test if your child needs to fast beforehand.

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