CT scan or sometimes called CAT scan stands for Computerized Tomography(CT) or Computerized Axial Tomography(CAT). It is a valuable, painless, diagnostic test that allows Radiologist (doctor who specialize in the use of imaging for diagnosing diseases) to view some areas of the body which cannot be viewed using conventional x-rays.

This imaging method produces a series of pictures that are then reconstructed by using computer into cross-sectional views. Since physicians can now view parts of the body they were never able to see before, they can detect many conditions in earlier stages, greatly optimizing patient outcomes.

GE LightSpeed VCT Scanner (64-slice)
Penang Adventist Hospital is using one of the latest sophisticated imaging tool call LightSpeed VCT. The LightSpeed VCT is able to non-invasively capture any organ in one second and capture images of the heart and coronaries in fewer than five heartbeats, something no other CT system can offer.

In a single rotation, the system creates 64 credit card-thin images, totaling 40 millimeters of anatomical coverage. These images are combined to form a three-dimensional view of the patient’s anatomy for the physician to analyze.

Computed Tomography (CT) systems, also know as a “CAT Scan” is a medical diagnostic tool that allows the visualization of internal structures within the human body. This aids physicians in diagnosing disease, viewing internal abnormalities and assessing the extent of trauma damage.

During a typical CT procedure, the patient is placed on a table. The table then moves the patient through the gantry (a donut-shaped device), which houses an x-ray tube and detector array.

For each image acquired, the x-ray tube rotates around the patient and the x-rays pass through the patient to the detector array, and thousands of x-ray measurements are acquired. The computer then processes this information and displays the corresponding images on a computer screen. This imaging technique avoids any superimposition of organs or tissues upon one another that might occur during other types of x-ray tomographic studies.

The CT examination creates images analogous to a single slice of bread from a whole loaf or a slice from an orange. Hence, the word ‘slice’ is often used to describe a view of patient anatomy.

The quality of an image depends on the nature of the x-ray source and detectors, the number and speed of the measurements made, the details of the reconstruction technique (algorithm), the machine characteristics, and the methods of data display and interpretation. The computer allows healthcare professionals to shade, rotate, correlate and measure anatomy in the image.

This data can be manipulated to derive even more precise clinical information. While conventional x-ray can discern tissue density difference of five percent, CT can distinguish a density difference of 1 percent or less, aiding in diagnostic confidence.

Benefit of CT Scan
With the currently new technologies, patients do not have to hold their breath long and the radiographers/technologist uses less contrast material. The new scanner can also be used to screen for various cancers more accurately determining whether the cancer has spread to other organs and can be early signs of cardiac blood vessel blockage.

Multislice CT (MSCT) continue to be useful in imaging as it can show several types of tissue includes Lung, Bone, Soft tissue and blood vessels. It is highly successful in detecting a blood clot or bleeding within the brain (intracranial bleed) shortly after a patient exhibits symptoms of a stroke.

MSCT technology has improved the accuracy of CT for many disease, for instances CT Angiography (CTA) is non invasive and less expensive than conventional angiography and allows clinicians to seen blood vessels without the need for more invasive procedures such as surgery, angioplasty and stents.

Faster image acquisition is beneficial to all patients especially elderly, pediatric or critically ill patients and populations in which the length of scanning is problematic. MSCT are also use to plan and properly administer radiation treatments (virtual CT simulation for instant Virtual colonoscopy) for tumors, CT guided biopsies and others minimally invasive procedures. These include peripheral imaging or femoral angiography with bilateral run-offs of lower extremities and CAC. With emphasis on the prevention of heart disease, CT cardiac calcium scoring is used to identify calcification of coronary arteries.

MSCT also offer flexibility by providing more choices in the design of the parameter used in CT study depend on patient’s condition, for instances, high resolution scan, thin slice imaging, improved spatial resolution, Laser scan times and better image quality. Thus, MSCT provides faster examination times and diagnosis.

About PAH Radiology Department

You will find our staff prompt, courteous and highly trained. Our receptionist will assist you to fill out the required paper work. All our technologists who operate the Lightspeed VCT Multislice CT scanner are certified nationally by Malaysia Registry of Radiology technologists. Our respected Radiologists will promptly interpret the results of your scan.

CT technologist performing CT scan

Safety

All of our equipment is maintained in top condition meeting not only the standards set by the Federal Government but also by Malaysia General Hospital’s Health Physicists.

MSCT scanner use x-rays, because x-rays can be harmful to a developing fetus, it is important to tell your doctor and the CT technologist if you are pregnant or even think you might be before you undergo the test.

Preparation for CT Procedure

You should not eat solid food for 3 hours prior to your test. You may, however drink plenty of fluids, such as water, broth, clear soups, juice or 'Milo'.

Medications

CT Abdomen with Oral Contrast coated in patient’s small intestine.

It is important for you to keep to your regular medication schedule. Please take all the medications that have been prescribed to you by your doctor – just let our staff know what medications you have taken prior to your test.

Depending on your medical condition and the type of test that your physician has ordered. You may request to drink a bottle of (barium sulphate) oral contrast before your test. This purpose is to visualize all your bowels in the scan to prevent from misinterpret as some others abnormality in your abdomen. Our CT technologist will explain to you if this is necessary.

Diabetic Conditions

If your have an insulin dependent diabetic condition, please continue to take your insulin as prescribed, but remember to drink extra fruit juices to make-up for fasting of solid foods for 3 hours period that your stomach is empty.

When to Arrive

If you are having a CT scan of your abdomen / pelvis, you need to arrive one hour before your scheduled appointment. This is to ensure that the Barium fluid you will asked to drink completely coats your gastrointestinal tract. The barium helps to highlight body areas for the CT scan. If you are having a scan other than abdomen / pelvis, you may arrive at your appointment time. Please do not forget to bring along your old reported radiograph if available.

Clothing

If you are having a head scan, dress in comfortable clothing. For all other examinations, you are most likely to change into a hospital gown. However, you may select to come dressed in your own loose comfortable clothes such as sweat tops and bottoms if that makes you feel more comfortable.

If there is no metal straps or zippers, you will not likely need to change into hospital attire. Our changing area is private and there is a secure locker for your clothes. It is best, however, if you leave your valuables at home. If you are wearing jewelry, dentures, glasses, hearing aids or any other metal objects, which might interfere with the CT scan, we will ask you to remove them.

Intravenous Preparation (injection)

Many of our patients receive contrast agent intravenously (intravenous contrast in a vein in their arm) during their CT test. If your doctor or our radiologist has determined that this procedure will enhance your CT scan result, the staff nurse will place on intravenous (IV line) in your arm prior to your going into the test.

Example of CT Non Ionic Contrast Agent

Contrast medium or contrast agents (sometimes called dyes) highlight your organ and blood vessels and help the radiologist to see them better. At a prior time, you may have already been injected with a contrast medium if you have had a kidney IVP examination, angiogram or even an earlier CT scan. In the past, those contrast agents contained higher level of iodine. The new contrast agents which we are using today have lower iodine content (Omnipaque 350 mg/ml) which greatly reduces the chance of allergic reactions and it is also reduce most of the discomfort associated with the injection.

The advantage of the GE LightSpeed VCT is that is maximizes the efficiency of the contrast medium, which tends to dilute quickly into your blood stream. Since our scanner is so quick, it is able to take all its concentration and this will produce high quality images.

CT Scan Examination

During Scanning

Our CT technologists will bring you into CT scan room where you will lie down on the patient table. The technologist will position the part of your body area you are having scanned in the middle of the large ‘doughnut-shaped’ scanner (CT gantry) which holds the xray tube and an electronic detector. The CT technologist will leave the scanning room, but is in full view and communication with you through the observation window in the adjoining room and closed circuit TV (CCTV).

Patient in the center of CT Gantry during examination

The scanner does not touch you, nor do you feel the x-rays. However it does make some noise and the table you are lying on may move slightly to make adjustments for a better view. It is important for you to lie very still and at some points, you may be asked to briefly hold your breath as the pictures is taken. During the scan, a thin beam of xray is focused on a specific part of your body. The xray moves very rapidly around this area, enabling multiple images to be made from different angles to create a cross-sectional picture. The xray beam information computer which analyses the information and constructs an image.

Length of Test

Each CT scan is tailored to each patient’s needs. In general, the actual imaging time with our scanner GE LightSpeed VCT lasts only about one minute or less. Many examinations require a contrast injection into a vein in the arm or hand. If your scan requires a contrast medium injection, the technologist/nurse will monitor the injection with you. Most examinations only last approximately 20 to 25 minutes in total, inside the scan suite. When finished you may then get dressed and leave as instructed by the technologist.

After the Test

You have no restrictions after having a CT scan and can go about your normal activities. To help eliminate the contrast medium from your body, drink plenty of decaffeinated or non alcoholic beverages. Water and juices work well.

CT Scan Results

Rapid results are essential not only for your peace of mind, but also for your physician to begin planning your treatment immediately. After completion of the test, the images are available for interpretation by the on-site resident radiologist. Because of our high technology interface with the hospital, there is no time wasted in handling the transfer of films.

Penang Adventist Hospital resident radiologist read scans within 24 hours, with faster result can be arranged in urgent situations. We will forward your results and films to your physician who will discuss with you.

Service Appointments

Your physicians may call 04-2227349 to make appointment for you. Generally; you can get an appointment within that day or next day. It very well depend on the demand of booking. When urgent, your physician can request a same day scan.

Prepared by Tan Jui Kok
Radiology Department Manager.