Beam And Scatter Radiation Restricting Devices DMI 50B Kyle Thornton.
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Transcript of Beam And Scatter Radiation Restricting Devices DMI 50B Kyle Thornton.
![Page 1: Beam And Scatter Radiation Restricting Devices DMI 50B Kyle Thornton.](https://reader036.fdocuments.us/reader036/viewer/2022062409/56649f565503460f94c79be9/html5/thumbnails/1.jpg)
Beam And Scatter Radiation Restricting Devices
DMI 50B Kyle Thornton
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Scatter Radiation
Compton interaction Higher kVp energies in diagnostic range
As scatter increases, radiographs lose contrast
Radiographs will look dull, blurred, and fogged
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Factors Affecting Scatter Radiation
kVp Field size Patient or part thickness
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kVp
Compton interaction increases with increasing kVp Scatter radiation increases
Scatter radiation is reduced by using collimators and grids
Decreasing kVp is not always desirable Increases patient dose
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Beam Field Size
As field size is increased, scatter radiation increases
Restriction of field size improves image quality
Even more important during fluoroscopy
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Patient Or Part Thickness
Scatter increases with patient or part thickness
A chest x-ray will result in more scatter than an arm x-ray
Compression devices reduce patient thickness and improve quality
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Compression Used to Decrease Effects of Scatter Radiation
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Beam-Restricting Devices
Two types of devices to reduce scatter Beam restricting devices Grids
Restricted for two reasons Reduce patient dose Improve image contrast
Three types of beam-restricting devices Aperture diaphragm Extension cones and cylinders Variable aperture collimator Positive beam limitation
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Different Types of Beam Limitation Devices
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Aperture Diaphragm
Simplest of all beam-restricting devices Lead or lead-lined plate with an opening Used with older head units Cannot see a light
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Extension Cones And Cylinders
Modifications of aperture diaphragms Primarily used for headwork, L5-S1 Fixed openings Generally not light localizing
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Cones and Cylinders
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Comparison of Sinuses W/W-Out Use of Cones
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Variable-Aperture Collimator
Light localizing Most commonly used A series of shutters and mirrors used Light field must coincide with x-ray beam
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Variable Aperture Device
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Schematic Drawing of the Variable Aperture Device
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Positive Beam Limitation Devices
Automatically collimates to the size of film used
Does not relieve technologist of having to collimate to anatomy of interest