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Intensifying Screen

Principles of Radiographic Imaging 5th Edition Chapter 22

QuestionAnswer
Delayed phosphorescent emission, also called screen lag Afterglow
The base material tha tthe film is made from; it is usually polyester, tough, stable, rigid, and uniformly lucent; it usually contains blue tent Base
The ability of the phosphor to emit as much light per x-ray photon interaction as possible, which is related to the screen speed Conversion Efficiency
The ability of a material to emit light instantaneously in responses to excitiation within 1 nanosecond Flourescence
Device used to amplify the incoming x-ray beam and reduce patient dose Intensifying Screen
When the incident x-ray photons match the K-shell binding energy of the phosphor, there is an increase in the characteristic production within the screen K-Shell Absorption Edge
Measurment of recorded detail, sharpness, and resolution; the minimum size and space between objects that can be visualized on the final image Line Pairs per Millimeter(lp/mm)
Measures the ability of a film/screen system to accurately measure the boundaries of an image Line Spread Function(LSF)
The ability of a material to emit light in response to excitation Luminescence
Measurement of recorded detail, sharpness, and resolution; measures the resolving ability of a film/screen combination Modulation Transfer Function(MTF)
The ability of a material to delay emission of light in repsonse to excitation Phosphorescence
A layer of material used in an intensifying screen that is capable of absorbing the energy of an incident x-ray photon and then emitting light photons Phosphor Layer
A layer of material used in an intensifying screen applied to the top of the phosphor layer to protect it from abrasions and stains; usually think plastic Protective Coat
A layer of material used in an intensifying screen to reflect light toward the film Reflective Layer
The most useful rating of intensifying screens; expressed with par-screens and film being arbitrarily assigned a relative speed number of 100 as a control point Relative Speed
Delayed phosphorescent emission; also called afterglow Screen Lag
An indication fo teh precise wavelength of light emitted by the phsphor Spectral Emission
How do intensifying screens reduce patient dose? Produce large quantities of light photons when struck by x-rays. Thereby amplifyingthe incoming x-ray beam and reducing patient dose.
What are the four basic components of an intensifying screen? Base, reflective layer, phosphor layer, and protective coat.
What characteristics should an intensifying screen phosphor possess? Resolution, speed, contrast and latitude.
What is the difference between fluorrescence and phosphorescence? Fluorescence is instantaneous emission whereas phosphorescence is a delayed emission.
What is the relationship between resolution and phosphor crystal size, layer thickness, and phosphor concentration? Phosphor cyrstal size and layer thickness are both inversely related to resolution and directly related to screen speed.
What is quantum mottle? Caused by an insufficient quantity of photons striking the intensifying screen
What is the purpose of a cassette? To create a portable, lightproof case for film to utilize the intensifying screens to best advantage and to attenuate the residual x-ray beam as much as possible.
What is the formula used to calculate a relative speed conversion from one film/screen combination to another? mAs1/mAs2=RS2/RS1
What are the three methods of measuring resolution? Line Pairs per Millimeter(lp/mm), Line Speed Function(LSF), and Modulation Transfer Function(MTF)
How is film/screen contrast related to latitude? The film/screen latitude is primarily dependent upon the latitude of the film, whichis directly realed to the contrast.
Created by: Dallas1856