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Physics
Unit #4
| Question | Answer |
|---|---|
| Digital radiography includes: | CR,direct and indirect |
| CR digital plates contain no __________ ________: | intensifying screens |
| CR phosphors are made of: | Barium fluorohalide doped in europium |
| __________ imaging uses conventional xray equipment: | CR |
| CR plate speed is typically within _____ to _____ range: | 200-250 |
| ADC stands for: | analog to digital converter |
| ____ converts light emitted information into digital binary coded numbers: | ADC |
| Input look-up table is also known as: | Grayscale rendition |
| ________ is used to smooth edges in an image and smooth jagged diagonal lines to produces seamless final images: | Anti-aliasing filter |
| _________ is used to convert digital images to analog form for image display: | Digital to analog converter |
| Optimal kVp range: | 60-120 |
| mAa (# of electrons is responsible for ______: | Sufficient phosphor stimulation |
| When insufficient light is produced _______ will increase: | Mottle or noise |
| ________ reduces patient dose, removes scatter, increases contrast: | Collimation |
| ________ is key to ensuring optimal image quality: | Collimation |
| _________ is a black background that can be added during post-processing to the edges to eliminate distracting white or clear areas: | Shuttering |
| There is no substitute for appropriate _________: | Collimation |
| A minimum of __% of the IR must be exposed for an accurate exposure index: | 30% |
| If collimation is less that 30% of the IR, what factor is affected: | EI # |
| Grids should be used for parts over __ cm: | 10 |
| Grids are especially important with ____ due to the hypersensitivity of the image plate phosphors to scatter: | CR |
| Smaller cassettes have _______ spatial resolution: | Better |
| Post-exposure image manipulation is known as _________: | Shuttering |
| Multiple imaging is not possible with what type of system: | Digital (DR) |
| Using the smallest imaging plate will result in the _________: | Highest sampling rate |
| CR reader scans the imaging plate at a _________ _______ frequency: | Relatively constant |
| The CR reader scans approx. how many pixels at a time: | 2000 X 2000 |
| Size cassette that has the best spatial resolution: | Smaller |
| Better spatial resolution results in ________ and _______ pixels: | Smaller and more |
| __________ is when grid lines are projected on the imaging plate when using low frequency stationary grids: | Aliasing or Moire |
| Unclean plate produce what type of artifiact: | White specks |
| Dirty plate readers will produce what type of artifact: | Horizontal white lines |
| Vertical bands result from what: | Dirty light guide |
| Vertical bands are represented in the image by what: | White on a normal image, black on image reversal |
| ________ _______ results in unattentuated scatter radiation striking the imaging plate: | Improper collimation |
| _______ is caused when the operator fails to follow collimation rules: | EDR, Exposure data recognizer failure |
| _______ prevents CR software from detecting the collimation boundaries: | EDR |
| _______ results in incorrect histogram analysis and inappropriate rescaling: | EDR |
| Creases cause what type of artifact: | Dark |
| Cracks in an ip plate will result in what type of artifact: | areas of lucency |
| Multiple field imaging errors include: | Inappropriate split fields, improper collimation, failure to adjust technique |
| __________results in histogram analysis error and rescaling error | Multiple field imaging errors |
| _______ results in too much raw radiation striking the IR and a skewed histogram: | Improper centering |
| Underexposure causes _________: | Mottle |
| Overexposure effects _________: | Contrast |
| Segmentation error due to incorrect body part/view selected: | Incorrect image processing |
| _____ uses a flat panel detector or CCD hard wired to a computer: | DR |
| ____ requires new installation of room or retrofit: | DR |
| DR images are available in less that __ seconds: | 15 |
| Image receptors in DR are called _______: | Flat panel or flat field detectors |
| ________ consists of a combination of detectors and TFTs: | Flat panels |
| The charge in flat panels is held in the _______ until readout: | Transistor |
| Direct capture uses what type of material as a photoconductor: | Amorphous selenium |
| Explain direct capture: | Photoconductor absorbs x-rays & converts them to electrical signal, TFT collects and sends signal to computer for processing |
| Explain indirect capture: | X-rays strike the scintillator to produce light, light is transferred to CCDs to be converted to electrical charge, charge is stored & sent to analog-to-digital convertor |
| Which type of DR is considered oldest: | Indirect |
| Indirect capture uses what material as a photoconductor: | Amorphous silicon |
| The photodiodes of indirect capture are comprised of what materials: | Cesium Iodide and amorphous silicon |
| Which type of system, indirect or direct reads a higher volume of pixels more quickly: | Indirect |
| Indirect capture reads approx. ____ million pixels per second: | 30 |
| ________ _______ offers improved spatial resolution at 20 lp/mm @ 100 keV: | Direct capture |
| The only system that utilizes a CCD: | Indirect capture |
| Benefit or Indirect is _______, while the benefit of direct is ________: | Cost, Increased spatial resolution |
| Indirect capture offers an average spatial resolution of _____ lp/mm: | 5 |
| ____________ is important in establishing the parameters that determine collimation borders and edges and histogram formation: | Image data recognition |
| What is image data recognition called in the following systems, Agfa, Kodak, Fuji: | Agfa-collimation Kodak-segmentation Fuji-EDR |
| ________ is when the image recording range is automatically determined: | Automatic data recognition |
| _______ is when the automatic mode is selected and the tech must select whether the field is divided for multiple exposures and in what pattern: | Automatic data recognition |
| _______ mode automatically adjusts reading latitude (L) and S numbers: | Automatic data recognition |
| ______ is an electronic device that receives the image forming x-ray beam and converts it into light image of high intensity: | Image intensifier |
| ______ allows for lower x-ray doses to be used on patients by magnifying the intensity produced in the output image, enabling viewer to see object being imaged: | Image intensifier |
| The overall image intensifier consists of what 5 things: | Input phosphor Photocathode Electrostatic focusing lenses Anode Output phosphor |
| The input phosphor of image intensifiers is made of what material: | Cesium Iodide |
| Cesium iodide converts x-ray beam to ______: | Light |
| The photocathode of an image intensifier is made of what material: | Cesium and antimony compounds |
| _________ in the image intensifier is responsible for photoemission: | Photocathode |
| The number of electrons emitted is _________ proportional to the intensity of light and photons: | Directly |
| The photocathode emits _______ when struck by light emitted by input screen: | electrons |
| ________ is a series of lenses inside the tube which assist in maintaining kinetic energy and focus the photoelectrons to the output phosphor: | Electrostatic focusing lenses |
| Electrostatic focusing lenses contain a ________ charge: | Positive |
| ________ is the primary source of brightness gain in an image intensifier: | Electrostatic focusing lenses |
| _______ is a circular plate with a hole in the middle: | Anode of image intensifier |
| The anode of an image intensifier is _______ charged: | Positively |
| Output phosphors in an image intensifier are made of what material: | Zinc cadmium sulfide |
| _______ emits and magnifies light 50-75 times when struck by electrons: | Output phosphors |
| Explain how an image intensifier works: | Exit beam interacts w/ Cs I & input phosphors then converted to light, Photocathode is stimulated by light & emits electrons, electrons are sent to anode, anode accelerates/focuses electrons to lenses, electrons interact with output phosphortoproducelight |
| Intensifying screens are used in _______ _______: | Conventional radiography |
| Image intensifiers are used in ____________: | Fluoroscopy |
| _______ is the most commonly used multi-field intensifier: | Tri-fold tubes |
| ____________ intensifiers allow more flexibility for magnification during fluoroscopic imaging: | Multi-field imaging |
| In tri=fold tubes the size of the output field remains fixed, so _______ is reduced: | Input field |
| A smaller input field size effects the following how, magnification, spatial resolution, patient dose: | Larger magnification Less spatial resolution Increased patient dose |
| ________ converts light image pattern to an electric signal and conveys the signal to a television monitor: | Television camera tube |
| The television camera tube uses a ______: | CCD |
| ________ receives light and store it: | CCD |
| A CCD is made of ________: | Silicon |
Created by:
akhernandez19