Computed tomography (better known as a CT scan) is a medical imaging procedure that uses X-rays to create cross-sectional images of different parts of the body. Those images, called \u2018slices\u2019, are digitally compiled together into a single image.<\/p>\n
Dr. Ania Kielar, President of the Canadian Association of Radiologists<\/a> and Vice Chair of Radiology at the University of Toronto<\/a> explains how CT scans work, when and why they\u2019re used and how long it takes to get your results back.<\/p>\n According to Dr. Kielar, CT scans are \u201cthe bread and butter of radiology\u201d because of the clear, detailed images the procedure provides. During a CT scan, a patient lies on a table, which is slowly threaded through a doughnut-shaped machine that rotates around them to take a series of X-rays. A computer then digitally combines those \u2018slices\u2019 into a detailed 3D image.<\/p>\n In a CT scan, the X-ray images are typically taken from different angles to capture a complete 360\u00b0 view, including:<\/p>\n After your scan, the images are sent to a radiologist who reads and interprets them and creates a report about the findings.<\/p>\n Both CT scans and MRIs provide clear images of the inner workings of the body to help doctors diagnose conditions or monitor treatment, but they use different methods to create those images. A CT uses multiple X-rays combined together by computer to create a single, highly-detailed image. An MRI captures images using powerful magnets and radio waves.<\/p>\n MRI scans can provide very clear images of soft tissues like ligaments, muscles or tendons, while CT scans of skeletal structures can be more distinct and defined. In terms of procedure length, a CT scan does not take as long as an MRI. In addition, CT scans are generally less expensive to produce, and the equipment is more widely available.<\/p>\n Your doctor will choose the kind of imaging procedure that is best for your particular circumstances and needs.<\/p>\n What a CT scan shows depends on what is being imaged. \u201cWe use CT scans for a lot of reasons,\u201d says Dr. Kielar. In the head, for instance, \u201cwe look at the bones in the skull, sinuses, the brain.\u201d<\/p>\n Radiologists also use CT scans to examine the internal organs and structures to identify many illnesses and injuries, such as:<\/p>\n Dr. Kielar explains that CT scans provide valuable information so doctors can properly assess what\u2019s going on inside the body. \u201cWe would look at the legs for a complicated fracture of, say, the knee or the lower leg or ankle. We would also scan the lower leg to look at the vessels to see if they\u2019ve got flow going in them or if they need bypass surgery.\u201d<\/p>\n Depending on the situation, patients may be given a contrast agent, which is a kind of dye, to improve the quality of the images produced. \u201cThe contrast agent helps the radiologist see all the organs and be able to identify what is happening inside of them,\u201d says Dr. Kielar. \u201cIt doesn\u2019t happen with all patients, it depends on the reason we\u2019re imaging the patient.\u201d<\/p>\n The dye, which might be administered either orally, rectally or through an IV, helps doctors better pinpoint and identify many issues, including:<\/p>\n The CT scan itself does not usually take very long, but preparation for the exam and getting into the right position can take time, anywhere from 30-60 minutes. According to Dr. Kielar, \u201cOnce they have you on the table in the right spot, it takes less than a minute.\u201d<\/p>\n The exact length of your CT scan appointment will depend on what part is being scanned and why, and whether or not a contrast agent is being used. \u201cIf you have to drink the oral contrast for a CT scan, that adds an extra half an hour,\u201d Dr. Kielar explains. \u201cIt\u2019s not like you just shoot it back, you have to drink the agent slowly over about half an hour. Then they take you over to the CT scanner and image you.\u201d<\/p>\n Your CT scan provides your medical team with information to help them diagnose or assess your condition. There are several steps you can take to prepare for your appointment:<\/p>\n CT scans are considered low-risk imaging procedures. X-rays use very low-dose ionizing radiation in the safest possible quantity. Dr. Kielar describes the dosage as \u201cALARA – As Low As Reasonably Achievable.\u201d But it is helpful to know all the possibilities so you can make informed decisions.<\/p>\n CT scans are non-invasive and do not typically require a recovery period. You can resume your regular activities right away after the procedure. That includes taking pain medications if you have any discomfort.<\/p>\n \u201cIf we use the contrast agent, we usually recommend people drink a reasonable amount of fluids after the scan,\u201d Dr. Kielar says. \u201cEven if the kidneys are working very well, we don\u2019t want that contrast to be inside of their veins for very long.\u201d If you drink plenty of water, 6-8 glasses, the contrast will be quickly flushed from your system.<\/p>\n If your CT scan is taken in a hospital, your results may be available the same day. For outpatient scans, the radiologist will read and interpret the scans, and send the results to your referring physician, typically within a week. Your doctor will then make a follow-up appointment with you to discuss your results.<\/p>\n With PocketHealth<\/a>, you can have early access to your CT scan images and reports, often as soon as they are released by the radiologist. PocketHealth is a secure platform where you can see, share and store your all your medical images and information in one place. Access your records today<\/strong><\/a>.<\/p>\n Your CT scan report will discuss your images from three views: coronal, sagittal, and axial, mentioning any abnormalities and highlighting any findings.<\/p>\n The radiologist interprets your images using the Hounsfield scale<\/a>. This common scale expresses how much X-ray radiation is absorbed by your body in Hounsfield Units (HU). High numbers on the Hounsfield scale represent dense tissue, which appears light or white in CT scan images. Low numbers represent non-dense tissue, which appears darker. Blood, for instance, is 60-90 HU, while bone is 300-1000 HU.<\/p>\n PocketHealth\u2019s Report Reader<\/a> provides definitions of complex medical terms to help you better understand your CT scan results. Report Reader also highlights any follow-up recommendations in the report, so you\u2019ll always be fully informed about the next steps to take.<\/p>\n In CT scan results, \u2018unremarkable\u2019 is actually a good thing. It means nothing unusual was found during your scan.<\/p>\n A CT scan compiles multiple X-ray images into a detailed 3D view of your body. CT scan images help your medical team diagnose illnesses and injuries and to monitor the progress of treatment.<\/p>\n PocketHealth<\/a> is here to support you, to help you access and understand your CT results so you can feel confidently prepared to advocate for your health.<\/p>\n Learn more<\/a> about how to use PocketHealth to access and share your CT scan records.<\/p>\nWhat’s a CT scan and how does it work?<\/h3>\n
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What is the difference between a CT scan and an MRI?<\/h4>\n
What does a CT scan show?<\/h3>\n
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What is a contrast agent and when is it used?<\/h4>\n
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How long does a CT scan take?<\/h3>\n
How can patients prepare for a CT scan?<\/h3>\n
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Are there any other concerns or risks that accompany a CT scan?<\/h4>\n
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What should patients do after a CT scan?<\/h3>\n
How much time does it take to get your CT scan results back?<\/h3>\n
How to understand your CT scan results<\/h3>\n
What does unremarkable mean on a CT scan?<\/h4>\n
Confidently advocate for your health<\/h3>\n
How PocketHealth works<\/h3>\n