Computed Tomography Scans

Grace Almeida


Godfrey Housnfield invented the Computed Tomography Scan in 1972. He thought abut Xray scans and decided that if you took xray's from various angles around the body he could get a 'slice' image. He first tested the CT head scanner machine on a fresh cow brain. Later he tested it on himself before presenting it to the Medical Community. It was first used in 1971 on a cerebral cyst patient in Wimbeldon. In 1975 Housnfild built a full body scanner

How does it work?

A CT scan forms a 3-D image made up of 'slices'. It uses Xray technology, the xrays are positioned at various angles. Xrays are practically shadows. So if a larger bone shadows a smaller bone in an xray you may not be able to see it in the xray. This is where CT scans help. They show from varies angles so a computer takes all these images and constructs the 3-D image.
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How have CT scans technology benefited people society?

CT scans have helped people and society in a variety of ways:

  • Seeing if it a surgery or operations are needed
  • Seeing what problems are without exploratory surgery
  • They improve cancer diagnosis and treatment
  • Patients do not have to stay in hospital as long for scans
  • Helps determine what treatment is necessary for common conditions (injuries, cardiac disease and stroke)
  • Helps determine which part of the hospital patients should be cared for in
  • See's the extent of the problem with less guess work

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This picture shows a "slice" of the abdomen. If you were looking a the patient, they would be on their back lying down and you would be standing at the foot of the bed looking towards the patients head tumour is seen near the top of the Pancreas. CT scans can also see the spread of cancer well because they also picture near by organs and lymph nodes.

Limitations of a CT Scan

CT scans although progressive and extremely beneficial to the medical world do have limitations.

-CT scans are expensive (thousands of dollars, although the price varies depending on which scan you need)

-CT scans have large radiation risks

-Can be misinterpreted

-Can break down

- Does not show medical history

- Can not be substituted for examining spinal fluid

- Requires trained staff

- Specalized equipment

-Larger patients do not fit

CT Scans: Know Your Radiation Risk

This article summaries that CT scans have radiation risks. It states that CT scans may cause approximately 29,000 future cases of cancer per year. The article states that a single CT scan has the same amount of radiation as 100-500 chest x rays. The article also says that doctors and hospitals still continue to order CT scans more than unnecessary putting the lives of their patients at risk. The article states that 20-40% of CT scans are should not have been ordered. The author believes that a doctor should know the risks and assess the situation before they choose for their patients. As most patients don't have enough knowledge on the topic to make an informed decision.


Radiological Society of North America, 2011 What are the benefits of CT scans?,Radiological Society of North America, accessed 10 May 2013, <>.

How CAT scans work, 2013, Discovery, accessed 16 May 2013, <>.

CAT Scan (computerized axial tomography), 2008, Pathology, accessed 20 May 2013, <>.

Computed Tomography (CT) - Body, 2013, Radiological Society of North America, accessed 21 May 2013, <>.

Drawbacks and Limitations of Computed Tomography, 2004, US National Library of Medicine, accessed 19 May 2013, <>.