Cat+Scans-+Abby+and+James

=**CAT scans** = = = = = = Overview of CAT scans = CAT scans are noninvasive medical tests to help doctors faster and more accurately diagnose and treat their patients medical conditions. A CAT scan is almost like a X-ray but has many is multiple X-rays that take many pictures of the body. A special computer then takes those single pictures and puts them all together to create a image of the inside of the human body. These scans can help doctors diagnose major medical problems faster and more accurate than conventional X-rays. ( CT Scan) ​ media type="custom" key="6306955" width="493" height="493" = Generations of CAT scanners =

1st Generation
A single X-ray source and a single X-ray detector collect all the data for a single __slice__. The source and detector are connected directly across from each other. An X-ray beam is sent across the two to obtain a __parallel__ __projection__ of the patient. The source and the detector are then rotated slightly and another projection is taken of the patient. This process is repeated for each __projection angle__. This generation is referred to as a translate/rotate scanner. (Generation) These videos show how CAT scans work and how the generations of CAT scans have changed in time. media type="youtube" key="fNaCxhhhZTE" height="385" width="480"

Because X-ray sources emit radiation over a large angle the efficiency of the CAT scan was greatly improved by using more X-ray sources and detectors. The X-ray sources and detectors all lie in the same __scan__ __plane__. The source and the array of detectors are just like the 1generation but there are multiple detectors. The X-ray beam measure by each detector is at a slightly different angle so each translation step generate multiple parallel ray projections. This generation scanner is much more efficient and faster than the 1generation scanner. This generation is referred to as a translate/rotate scanner. (Generation) media type="youtube" key="Ni4Hsi3GhXo" height="385" width="480"

With improvements in detectors and data acquisition technology, it was possible to design a array of detectors with enough __high spatial__ __resolution__ cells to allow simultaneous measurement of a fan-beam projection of the entire patient cross-section. With the larger detector it was no longer necessary for the detector to move past the patient. The whole source/detector assembly simply rotates around the object. The imaging processing is greatly improved from the 1and 2generation scanners. However very high performance detectors are needed to avoid __ring__ __artefacts.__ Also the system is more sensitive to __aliasing.__ This generation scanner is referred to as a rotate/rotate scanner. (Generation) media type="youtube" key="bdf0kXn5Eeg" height="385" width="480"

4th Generation
Design was made using a stationary detector ring and a rotating X-ray tube. The stationary detector ring requires a larger angle of acceptance for radiation, in return forth generation is more sensitive to scattered radiation. Needs more detector cells to obtain the same spatial resolution as in 3Generation. This Generation is referred to as rotate/stationary. (Generation)

This photo also shows the different Generations of CAT scanners.

= Definitions of underlined words = Slice: a view of an imaged tissue Projection: a picture, such as a radiograph of a CAT scan Projection Angle: the angle that the x-ray beam is shot at Scan Plane: the plane of the patient that is being scanned Spatial Resolution: the ability to be able to distinguish between two adjacent structures Ring Artefacts: circular abnormalities that affect the clarity of the CAT scan image Aliasing: distortion caused when an image is converted from analog to digital

= Importance of CAT scans = CAT scans are very important in the medical field of work. Many people owe their life to CAT scans. CAT scans make it much easier for doctors to diagnose patients with medical problems and diseases which with out the CAT scan would not have been found. They also help doctors decide if they need to operate on their patients or if they can just leave the injury or medical problem the way it is so it can heal. I myself owe CAT scans a great deal of thanks. The doctors did not know if my vertebrae was touching the spinal chord or was close to it, if it was if i moved my back far enough in a certain direction i would have been paralyzed from the arms down. The doctors found out if my vertebrae was close to my spinal chord by taking multiple CAT scans of my back and neck. It turned out that the vertebrae was too close to my spinal chord and was only a compression fracture not a burst fracture. CAT scans are very important in the medical field. In many cases CAT scans keep doctors from having to amputate, conduct surgery, and prescribe medicines that may hurt the patient.

= The Making of X-rays =

The x-rays in a CAT machine are generated by an x-ray tube, called a Cooledge tube. On one end of the tube, which is kept in a partial vacuum, there is the wire cathode. When a low voltage is run through the tungsten cathode, the cathode heats up and electrons separate from the wire and are attracted to the anode, which is usually made from copper or tungsten. The hotter the filament, the more electrons that break free of the wire and the higher the energy the electrons have when they hit the anode, so the higher the intensity of the x-ray particles. The reason that x-rays are generated is that when the electrons hit the anode, some of the particles come close to hitting the nucleus of the tungsten atoms, but the positive charge of the nucleus deflects the electron. There is a loss of energy as the electron is deflected away from the nucleus. This energy is emitted from the electron in the form of x radiation. X-rays can be seen on the electromagnetic spectrum in between gamma rays and ultraviolet rays. The frequency of the x-rays produced in the x-ray tube depend on the energy of the electrons that hit the anode; the higher the energy of the electrons, the higher the frequency of the x-ray beams. ( X-Ray Generators)

This file is a animation and explanation for how X-rays are created in the CAT scan.





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= Works Cited =

"The American Society for Nondestructive Testing." //The American Society for Nondestructive Testing (NDT)//. Web. 03 June 2010. . "CAT Scan (CT) - Body." //RadiologyInfo - The Radiology Information Resource for Patients//. Web. 03 June 2010. . "CT Scan | Computed Tomography | CTA." //Neurosurgeons Neurosurgery Mayfield Clinic Cincinnati, Ohio US//. Web. 03 June 2010. . "Medcyclopaedia - CT Generation." //Medcyclopaedia - Medcyclo.com//. Web. 04 June 2010. . "This Month in Physics History." //APS Physics | APS Home//. Web. 03 June 2010. . Volume, Reformatting The. "Computed Tomography." //Psychology Wiki//. Web. 03 June 2010. . "YouTube - Mtmmk51's Channel." //YouTube - Broadcast Yourself.// Web. 03 June 2010. . "X-Ray Generators." Web. 04 June 2010. . "X-rays." //Welcome to the Physics Department at ISU.// Web. 04 June 2010. .

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