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RADT 465: QC
Question | Answer |
---|---|
Characteristics determining image quality: visibility factors | Brightness & grayscale/contrast p.314 |
Characteristics determining image quality: Geometric factors | Spatial resolution & distortion p.314 |
The function of contrast is to make details ____ | visible p.314 |
HIGH contrast is ____ scale contrast | short - few, very different, images/tissue densities p.314 |
LOW contrast is ____ scale contrast | Long - many similar image/tissue densities p.314 |
Any combination of mA and exposure time that will produce a particular "mAs" will produce identical receptor exposure is know as | Reciprocity law - if 10 mas is required to produce a given receptor exposure, all combinations should produce identical results: 100mA and 100ms, 200mA and 50ms, 300mA and 33ms. p.315 |
mAs is ____ proportional to receptor exposure | directly p.315 |
mAs is a _____ factor regulating the number of of photons | quantitative p.315 |
T/F: mAs has lots of impact on contrast | F: Kvp p.315 |
_____ contrast refers to body tissue densities and their differential absorption of the x ray beam | subject p.315 |
As distance between the x ray tube and the IR (SID) increases, exposure rate decreases according to the __________ law | inverse square law p.315 |
Kv affects both ___ (energy/wavelength) and ___ of the x ray beam | quality and quantity p.317 |
Kv regulates beam _______ and has a significant impact on image contrast in analog imaging | quality/penetration p.317 |
Whatare some factors that determine production of scattered radiation | Field size/beam restriction, kilovoltage, thickness/volume and density of tissues p.318 |
scatter radiation carries no useful information but adds ___ in the form of ___, thereby impairing visibility of detail | noise, fog p.318 |
As the size of the x ray field is reduced, there are less area and tissue volume for ______ to be generated | scatter radiation - reducing the field size takes the low energy photons out and only allows the high energy photons to get through causing less scatter radiation p. 320 |
scatter radiation i s a result of x ray photon interaction with tissue atoms via ____ scatter processes and adds quality degrading fog to the radiographic image | Compton p.320 |
what are the 2 RADIATION PRODUCTION interactions | bremsstrahlung & characteristic (worksheet) |
T/F: all radiation production interactions start with an electron | T: not a photon (worksheet) |
incoming electrons slows around the nucleus in the target atom; what interaction | bremsstrahlung (worksheet) |
incoming electrons interact with any inner electron in the target atom | characteristic - really want electron to react with the K (most inner shell) to get the most energy x ray (worksheet) |
filtration _____ overall average energy of the x ray beam | increases - taking out the low energy photons p.328 |
filtration has a total filtration of _____ mm Al equivalent | 2.5 mm p328 |
Beam restriction ____ the production of scattered radiation and, consequently, _____ receptor exposure | reduces, decreases p.332 |
what is the percentage for a single phase? | 100% p.333 |
what is the percentage for a three-phase 6 pulse? | 13% p.333 |
what is the percentage for a three-phase 12 pulse? | 4% p.333 |
what is the percentage for a high frequency? | less than 1% p.333 |
______ is the ability to manipulate the image after exposure | postprocessing p.334 |
a ______ is a graphic representation of pixel value distribution demonstrating the number of pixels and their value | histogram - remember all the information of the anatomy is between s1 and s2. there are 3 different types of histograms. p.334 |
what are the 2 types of AECs | phototimer & ionization chamber pp.337 |
______ identifies grayscale values | bit depth p.337 |
As SNR _____, noise in the form of graininess ______ | decreases, increases p.337 |
_____ is used to automatically regulate the amount of ionizing radiation delivered through the anatomic part to the IR | AEC p.337 |
____ utilizes selection of anatomic part, rather than selection of specific technical factors. | APR p.341 |
________ is the term used to describe the IR's impact on image detail | spacial resolution p.348 |
Digital image resolution improves with .... | smaller pixel size, smaller pixel pitch, larger image matrix, greater pixel density p.348 |
spatial resolution factors for direct digital (DR) | pixel pitch & DEL size of the TFT p.348 |
spatial resolution factors for indirect digital (CR) | pixel pitch & sampling frequency p348 |
DQE stands for | detective quantum efficiency p.349 |
As the matrix size is _____, there are more and smaller pixels in the matrix, therefore improved ___________ | increased, spatial resolution p.349 |
_____ describes the percentage of incoming x ray photons that are deteced and absorbed by the detector for transformation to the x ray image | DQE p.349 |
how can does one shorten the life span of the x ray tube? | delivering heat to the x ray tube in a short period of time p.358 |
_____ focal spot size = ____ blur = ____ detail | increase, increase,, decrease p.359 |
The use of a small/large focal spot size improves spatial resolution but generates more heat at the anode | small p.359 |
CR resolution is improved by (3 things) | smaller barium fluorohalide phosphors, narrow width laser beam, larger monitor matrix. p.370 |
___ is conversted to an electrical signal and transferred to the ADC; digital data are then transferred to DAC | PSL p.375 |
____ is the most typical in extremity imaging | PSP p.375 |
____s function to manipulate grayscale values to provide the appropriate grayscale rendition | LUTs p.378 |
_________ compensates for too little/too great an exposure | automatic rescaling p.378 |
low frequency, ___ wavelength, __ energy | long, low p.389 |
high frequency, ___ wavelength, __ energy | short, high p.389 |
X ray photons can (3 things) | pass through part, be absorbed by the part, scatter within the part p.391 |
______ change mechanical energy to electrical energy | Generators p.394 |
______ change electrical energy to mechanical energy | motors p.394 |
AC consists of _____ waves | sinusoidal p.395 |
X ray tube consits of what 3 things | anode (positive electrode), cathode (negative electrode), glass envelope (vacuum) p.408 |
The anode has a ____ disk with beveled edge, ____ alloy focal track, ____ stem for support for anode disk | Graphite/molybdenum, tungsten/rhenium, molybdenum. p.408 |
The induction motor does what 3 things | rotates the anode, stator (outside the glass envelope), rotor (inside glass envelope). p.408 |