Running Head: COLLIMATION 1
The Effect of Collimation on the Primary Beam & Collimation Affecting Patient Dose, Scatter,
Contrast, Density/Brightness and Noise
Ashley Young
Rasmussen College
8/26/17
Author Note This paper is prepared for Physics RTE 1100 Lab, taught by Gillian Kubitschek.
COLLIMATION 2 Collimators are the best beam-restricting device that can change the size of the x-ray beam. Collimators can also be called beam restriction because of this. The effect collimation has on the primary beam is that it limits the x-ray beam field size. The beam restricting device alters the size or shape of the primary beam. Depending on the anatomical structure x-rayed,
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In case of the light not working, an x-ray field measurement guide can be used. The collimator also consists of a plastic template with crosshairs. “Collimators have two sets of lead shutters that are used to change the size and shape of the primary beam.” (Fauber,
2016, pg. 144). Beam-restriction devices lower the amount of tissue that is exposed to radiation and is, therefore, limiting the amount of scatter radiation created.
Collimation effects patient dose or, the amount of radiation the patient receives because by using collimation it causes the patient dose of radiation to decrease. The reason the radiation is reduced is that there is less scatter radiation created when using the correct field size for the particular structure that is radiographed. If the collimation is increased then, the field size decreases and the patient dose is reduced. If the collimation is decreased then, the field size increases and the patient dose is therefore increased. The collimation effects scatter radiation by decreasing the quantity of scatter radiation and lowering the amount of radiation the patient
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The use of a cylinder in place of a cone will create a better-detailed image. When the collimation is decreased, the amount of scatter radiation that is formed increases. When the collimation is increased, the amount of scatter radiation decreases and the radiographic contrast becomes greater.
Using the collimation will affect the density and brightness of an image. If the collimation is increased the radiographic density is lowered. When there isn’t the right amount of mass, the digital image will have quantum noise. When the collimation is increased, the quantum noise also increases. The quantum noise is not useful because it gives the image less detail. The quantum noise decreases the quality of the radiographic image. The visibility of brightness or density changes is quantum noise. It is very important to minimize or limit the amount of quantum noise for each every image. When the quantum noise is increased by increasing the collimation creates an insufficient x-ray exposure to the picture making the image less precise.
If the x-ray field and the exposure field is not aligned properly and the Bucky tray and light is not aligned correctly could very possibly affect the quality of the image.
In dentistry there is a need for taking an x-ray, the x-ray is a way to help the dentist diagnose a patients oral hygiene and to see if there are any other areas in the mouth that may need to have any type of work. The dentist or the assistant will want to make sure that they can get all the teeth possible in the radiograph (x-ray) as possible to reduce the amount of exposure to the patient. Most people will have exposure to radiation just from standing outside in the sun for a long period of time, which is what we call “background exposure”.
"Production of Refractory Metal Powders," in Powder Metal Technologies and Applications, vol. 7, 1998, pp. 188-201.
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"Imaging and radiology." Magill's Medical Guide, 4th Rev. ed.. 2008. eLibrary. Web. 16 Dec. 2013.
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...ion is less than the maximum allowed deflection of 0.048m so the beam does not fail
Schenter, Robert. Nuclear Medicine Research Council. 18 Nov. 1998. Nuclear Medicine Research Council. 4 Apr. 2005 <http://www.cbvcp.com/nmrc/>.
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