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.
...e level for the high dose radiotherapy protocol. Also, the observations shows that patients that survive the treatments should be watched over a longer follow-up time [5].
K. Brown, P. Williams, J. Wong and D. Yan, "Collimator for radiotherapy apparatus US 6,714,627 B1," 30 March 2004. [Online]. Available: www.google.com/patents/US6714627.
2. Intensity Modulated Radiation Therapy (IMRT) is also used by modifying the radiation beams by varying their intensity. This is a more specialized form of the 3D-CR treatment.
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Driver, (2013), described the DEXA scanner as a machine that produces two x-ray beams of high and low energy levels. Much like fluoroscopy, the x-ray from the DEXA scanner comes from underneath the patient, and the scanner has a very low x-ray dose. Earlier versions of the DEXA scanner emitted radiation which required up to five minutes to scan an area of interest, but the more advanced machines can take as ...
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"Imaging and radiology." Magill's Medical Guide, 4th Rev. ed.. 2008. eLibrary. Web. 16 Dec. 2013.
...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/>.
Filter length: in shorter synthesis basis functions are desired for minimize deformation that affects the subjective quality of the image. The longer filters are responsible for ringing noise in the reconstructed image at low bit rates.
The image-intensifying tube is extremely intricate and allows for the conversion of the x-ray beam to be converted
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