Computed Tomography Scans

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CT Scans

Text of Computed Tomography Scans

  • 1. Computed Tomography (CT) ScansBrandon Lau Edward L 4B IB Psychology

2. Background information X-Ray Computed Tomography is a medical imaging procedure using computer processed x-rays to produce tomographic images The produced cross-sectional images are used primarily for diagnostic and therapeutic processes Greek Foundation of the word: Tomo = Slice Invented by Hounsfield and Cormack in 1972, both won Nobel prize for the invention About 6,000 CT scanners in US and about 30,000 worldwide today 3. Background Info (cont.)Usage of CT scans has dramatically increased over the past two decades Estimated 72 million scans were performed in the United States in 2007 Older versions of the scan were known as Computed Axial Tomography or CAT Scans Although previously images produced were in the axial plane (limited to one angle), modern scanners allow data to be reformatted as volumetric 3D representations of structures 4. How it works Since the 1970s, CT scans have become an important tool in medical imaging to supplement X-rays and medical ultrasonography Unlike simple X-ray scans, the combination of computed technology allows soft tissue to be visible A x-ray tube and detector are physically rotated behind a circular shroud Pixels in an image obtained by CT scanning are displayed in terms of relative radio-density Images can be acquired from any angle and at any depth 5. How it works (cont.) - Patient lies flat on back on a flat bed - X-ray tube rotates around body of patient -Patient will be moved continuously through this rotating beam -Rays are analyzed by detector on opposite side of body 6. Results of CT ScanA visual representation of the raw data is referred to as a sinogram (not yet sufficient for interpretation) Data must then be processed using a form of tomographic reconstruction This process produces a series of crosssectional images Can show a full body CT scan or be focused on just the brain/head Images produced are called Tomograms Individual scans can be combined to create 3D images 7. Strengths Has many advantages over traditional 2D medical radiography Eliminates the superimposition of images of structures outside the area of interests Differences between tissues that differ in physical density by less than 1% can be distinguished Capable of showing soft tissue and structural changes eg. Brain tumors, Brain damage, Liver, and other organs Far more useful than an MRI in terms of skull fractures Cheaper than a MRI but equally as fast Can be performed on patients with implanted medical devices 8. Weaknesses Can only produce structural images Unable to provide any information on brain activity Inferior to MRIs when it comes to soft tissue contrast Potentially Dangerous (see next slide) 9. Dangers Exposure to radiationEspecially dangerous to young children and pregnant women Half of all CT scans in the United States involve intravenously injected radio contrast agents Mild side affects of these agents include nausea, vomiting, and rashes Rare cases of extreme reactions include contrast-induced nephropathy, occurring in approximate 2-7% of people who receive these agents Ionizing radiation in the form of x-rays are energetic enough to directly damage DNA Small increased risk of cancer 10. Citations Siemens Medical Solutions. (n.d.). Retrieved from http://www.imaginis.com/ct-scan/brief-history-of-ct Stoppler, M. C. (n.d.). Retrieved from http://www.medicinenet.com/cat_scan/article.htmImages From: http://www.callusdoc.com/AImages/canstockphoto4116197%20(1).jpg http://media.web.britannica.com/eb-media/59/62659-004-A8C6FDA4.gif http://assets.knowledge.allianz.com/img/ct_scan_head_q_1_48138. http://dz-world-health.blogspot.com/2012_07_01_archive.html