Advantages of the flat panel detector over the conventional image intesifier. (3 things)

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Imaging Equipment

Final Review-Radiologic Technology

Question	Answer
Keeping the last image displayed on the monitor	Last image hold
The time it takes for the x-ray tube to be switched off	extinction time
Grouping sets of 4 smaller pixels together to form a larger effective pixel when taking spot films	binning
Actual radiographic technique factors area adjusted to compesate for fluctuations	ABS
Amplification of the electronic signal (current) is increased or decreased as needed by the circuits	AGC
A series of short visual checks, rather than continuous fluoro, dramatically reduces cumulative exposure to the patient	intermittent fluoro
Scattered random light from the output phosphor	veiling glare
Lower frame rates than realtime fluoro/ automatically spreads out the fluoro on time to reduce patient dose	pulsed fluoro
Indicates the emission of light	scintillation
Reduces the FOV on the input phosphor	magnification mode
Slight magnification and increased blur around the periphery of the image	pin cushion distortion
Loss of brightness toward the periphery of the image	vignetting
The ratio of input area to the output area of the image intensifier	minification
converts the xray image into an electron beam that will be accelerated and focused for intesification onto a TV	Image intesnsifier
The time it takes for the xray tube to be switched on	interrogation time
T/F Grid cut-off is not an issue in fluoroscopy	TRUE
Primary source of operator radiation exposure during fluoroscopy	Patient
Image intensifiers at a basic technological level	Energy conversion tubes
What negatively impacts spatial resolution in fluoroscopy	Binnning
Concentration of electrons onto an output phosphor much smaller than the input phosphor	Minification
How long the x-ray is off for	pulse interval
smaller anatomical area is displayed with the same number of pixels available on the monitor	multifield intensification
number of photons generated at the output phosphor for every photon generated at the input phosphor	flux gain
Increases by the mAs setting as more photon flux is needed	pulse height
Duty Cycle	Pulse width
Advantages of the flat panel detector over the conventional image intesifier. (3 things)	High SNR More FOV Wide dynamic Range
Who invented the fluoroscope	Thomas Edison
II concave shape main purpose	distance between photocathode and output phosphor is exactly equal
Fluoro grids match	Input phosphor (circular)
Key advantage of spot filming as compared to the dynamic image	improved spatial resolution
Stopping and starting fluoroscopy using a dead-man's switch and under manual control of exposures	intermittent fluoroscopy
In order to shift the electron stream focal point to the correct position in a multi-field image intensifier	a stronger negative charge is placed on the electrostatic focusing lens
Minimum source to table distance of a mobile fluoroscopic unit within QC measures	30 cm (12 inches)
To maintain the same brightness gain, a decrease in flux gain would require	Increase in minification gain
Longer widths of pulsed fluoro results in	Increased patient exposure (and more blurring)
Conventional fluoroscopic mA is usually about	0.5-5 mA
FPD fluoroscopy (3 things)	cover more anatomy than i.i. Rectangular shape Capable of radiographic exposures
Major distinction between digital and flat panel fluoroscopy system designs is the position of	fluoroscopic xray tube
When utilizing Mag mode 2, what should you except to happen when switching to mode 1	Decreased spatial resolution
What two things happen with mag mode will increase	patient exposure, Resolution
Describe the term "gain" in I.I.	Amplification of electrical signals
Product of minification gain and flux gain is calculated to determine	Total brightness gain
two types of electrical devices that will change the level of brightness to compensate for differences in part thickness and tissue density	automatic stabilization control Automatic gain control
placing the tube beneath the patient beneficial	more intense radiation levels below the knees of the operator
Volt potential difference needed to accelerate electrons rom the cathode side to the anode side of I.I.	25,000-30,000
Electronically, functional unit of FPD in fluoro	DEL
Operating the image intensifier tube in the____ mode can help reduce pincushion distortion	magnified
Photocathode is an electrical device which emits	electrons
T/F Placing a fluoroscopy room too close to an MRI department, could cause a distortion artifact to an image intensifier system	True
The output phosphor of an I.I. changes _______ energy into ________energy	electron;light
CCD video imaging uses what type of technology	Solid-state computer chip
T/F Longer frame rates allow less smearing if a fluoroscopic procedure requires panning or sweeping	False
The product of minification gain and flux gain is calculated to determine	Total brightness gain
For image intensifiers, there are two types of electrical devices that will change the level of brightness to compensate for differences in part thickness and tissue density, the automatic stabilization control	Automatic gain control
Placing the x-ray tube beneath the patient..	Beneficial because there is more intense radiation levels below the knees of the operator
What is the volt potential difference needed to accelerate electrons from the cathode side to the anode side of an image intensifier	25,000-30,000
Electronically, the functional unit of FPD in fluoroscopy is the	Detector element (DEL)
T/F Signal to Noise (SNR) ratios should be kept as high as possible	True
What innovative software is strongly recommended for all mobile and trauma x-ray procedures, allows to work as the patient lies. No grid cutoff from angling, alignment and positioning	Virtual grid software
T/F High DQE, like 0.8, reflects a low transfer of information from the detector to the output image	False
If the dynamic range or bit depth of a digital processing system is too limited, it is possible for ________ to occur when either brightness or contrast are adjusted	Data clipping
Ghost images can be caused by all of these except	Under exposure of the IR
T/F Sudden deviations in focal spot size indicate damage to the cathode	False
T/F Quality Assurance is for monitoring quality patient care, and QC is about monitoring the quality of our equipment	True
This describes the power of the light flow (flux) traveling through space	Lumens
For light emitted isotropically in all directions from a source, one candela generates one lumen of light intensity per meter	Steradian
Spatial Frequency is measured in (three things)	LP/mm, Lp/cm, Cycles/pixels
"Black Bone" is another way to say the image is	Positive
CR QC requires beam angulation cannot be off by more than	2 degrees
The kVp of any x-ray beam should not deviate by more than ___% from the read-out from the kVp	5
Post processing technique that is key in displaying C7-T1 junctions is	Targeted area brightness
To prevent aliasing artifacts, a CR image should be processed with	the laser scanning lines and the short dimension of the grid lines in perpendicular
The post processing procedure called stitching means	2 or more images are combined together
Size of the projected light field (collimator) must be within plus or minus the x-ray beam	2% of SID
Halo Effect occurs as a result of too much	Edge enhancement
On SMPTE test pattern and other test patterns for electronic image display monitors, there are sets of adjacent squares with JNDs in density between them	Contrast resolution/gray scale
What QC calibration should fall within plus or minus 5%	exposure timer and exposure reproducibility
Ever radiographic image must include	Date of exam RT LT marker Patient DOB
Are Ei or S number required to be ON the image	No
The use of repeat analysis in a radiographic imaging department provides pertinent direction	Inserve topics management decisions cost-efficiency data
T/F DQE is better in computed Radiography vs. Indirect Radiography	False
Which filter application uses waves in relations to space to change/enhance the image	Frequency
Stationary Fluoro	38cm (15 inc)
X= output signal amplitude divided by input signal amplitude	MTF
What QC checks can be reasonably performed visually by a radiographer	Field uniformity Erasure thoroughness or ghosting Uneven spatial resolution
Repeat rate to strive for	3-5%
mA station be linear to two adjacent stations	10%
X= SNR squared of output divided by SNR squared of input	DQE
<30% from average: consistency of a single brightness level displayed across the area of the display screen	luminance uniformity
+/- 5% The ability to repeat the same overall technique settings and obtain the same results iin actual exposure	exposure reproducibility
Assesses dexel reactions to an exposure for evenness of exposure, utilize a long SID to decrease the anode-heel effect	Field uniformity
The thickness of absorber material required to reduce the intensity of the x-ray beam to one-half its original value-- 2.5 mm Al or more	Half-value layer
+/- 10% exposure accuracy linearity that requires a back up time check as a part of its QC	AEC reproducibility
Utilizes LP/mm on a lead template to assess focal spot accuracy	Slit camera
+/- 2% SID can use plexiglass cylinder or 8 pennies to measure accuracy	collimator check
+/- 5%; High voltage diaode or oscilloscope is used to measure accuracy	kVp calibration
+/- 5% monitors the time allowed for the electrons to flow from the cathode to the anode for a specific period of time	exposure timer
an increase in FSS at increased tube current and/or decreased tube potential; effects spatial resolution	focal spot blooming
Within 10% of each other; the accuracy of a particular mA station relative to the 2 adjacent mA stations	mA linierty
Uses a SMPTE pattern to evaluate monitor quality	image display system
+/- 2% SID; use a tape measure to measure from the anode (red+) to the imaging plate	distance
10% differences in adjacent squares on SMPTE pattern within 10% accuracy	grayscale standard display funciton
Artifact occurs during CR processing due to grid lines overlapping laser readouts	Miore and Aliasing
The minimum filtration required on an x-ray unit	2.5 mm Al equivalency
T/F low MTF values like 0.2, meants the image is displaying high spatial resolution/frequency	True
The post process procedure called translation means	an image is flipped right to left or vice versa
T/F HVL improves beam quality	True
with QC program in place, what is the majority of repeat exposure	Positioning
T/F CR image can avoid alignment issues if 1/4th of the image receptor is exposed	False-- Must be 1/3 of the IR
Single CR phosphor plate is erased and then processed without exposing it to xrays. This is a test for	intrinsic (dark) noise
Device designed to directly measure luminance, or the light intensity emitted from the display monitor	photometer
Clss 1 LCD must have _____ or fewer bad pixels across the entire area of the monitor	15
Dynamic range compression	Supports tissue equalization
How many pixels does it take for a monitor to fix a dead pixel	8
Represents the point in the histogram where pixels must start to be eliminated from brightness correction calculation	Smax
Histogram, what does the x-axis represent	Specific exposure values captured by the receptor
Which of the following modalities generally produces the sharpest images, due to large image matrix size and very small pixels	DR
Selection of a narrow window width will	increase contrast in the image
determined by the computer by finding the mid-point between SMIN and SMAX in the main lobe of the generated histogram for the image	exposure indicator
A marker for exposure quality that porvides the radiographer with an indication of accuracy of their technique	Exposure index
Ratio or percentage of original xray beam intensity absorbed by a particular tissue area in the patient	Attenuation coefficient
A post processing funciton that changes raw data into a favorable image	Rescaling
Quanitfies the difference between the actual EI and target EI	Deviation index
Range of pixel values actually present in a displayed image at 1 moment	Gray scale
Gradual acceptance over time to use higher radiographic exposures, and hence doses to the patient, for the same xray exam and projection	dose creep
Maximum shades of gray a system store for you to use per pixel	bit depth
Frequency of recorded exposure values recorded by the image receptor	histogram
Range of exposures that produce quality images at an appropriate patient dose	exposure latitude
Process of the ADC taking electronic signals and changing them to brightness levels displayed in pixel values	Quantization
Range of exposures that can be captured by the detector	Dynamic Range
Detector elements are responsible for capturing the aerial image and converting x-rays into	electric signals
T/F the more zoom applied to an image the better the spatial resolution is represented	False
The higher the fill factor in the dexel the _____ the spatial resolution	better
T/F using incorrect collimation can create a histogram analysis error	True
Saturation of an image occurs when	Exposing the patient to 8 times too much radiation
What step in digital image processing identifies the useful pixel values in an image	histogram analysis
Which device can be used in place of a photomultiplier tube in CR reader	CCDs
Histogram analysis failure is less common with DR systems because the DR algorithms use the data set for processing	only exposed dexels
T/F the tail lobe on a histogram represent barium or a prosthesis	False
xray exposure above the level of detectors dynamic range	Saturation
What would result in a displayed digital image which is brighter	decreased window level
Element for scintillation	Gadolinium oxysulfide
Element for Direct photoconductor	Amorphous Selenium
Element for the phosphor layer	Barium Fluorohalide
Element for Indirect Photodiode	Amorphous Silicon
Element for CR processor	Helium Neon
CR or DR Scinitllator	DR
CR or DR TFT	DR
CR or DR Digitizer	CR
CR or DR Translation	CR
CR or DR Double exposure artifacts	CR
CR or DR F centers	CR
CR or DR Radiation fog artifacts	CR
CR or DR Dexels	DR
CR or DR photostimulable phophors	CR
CR or DR Latent image	CR
What is the bit depth of a 6 bit system	64
Steep S curve through a histogram represents a ______ image	short gray scaled
Fill factor of a detector element	xray sensitive portion of the detector
Range of the image gray scale is controlled	window width
For a large abdomen which completely covers the image receptor place the expected shape of the original histogram	with no spikes, only the main lobe
What is the role of the PMT-Photomultiplier tube	collect and multiply the light photons
What aspect of an image receptor system creates bursts of light	Scintillation layer
T/F Cesium Iodide is an element utilized in scintillation system for a direct capture DR imaging	False-- scintillation is not used in Direct capture, just indirect
CR, the image information that is stored on the imaging plate prior to processing	latent image
Rad must view images within	the steridian
Device that acts as a switch to release the electric charge collected by the detector element	TFT
T/F Lossless compression is adequate to sustain high spatial resolution in digital imaging	True
Which device in the image receptor converts light into electrons	Photodiode
The laser light in the CR exposes the plate in a rapid back and forth motion	Raster pattern
Luminescence refers to a release of	light photons
What is the initial response of CR phosphors when the phosphor layer of the imaging plate is stimulated by xrays	Release of light photons
Imaging and archiving systems in radiology communicate using what digital format	DICOM
A reference histogram that evolves by averaging it with the previous 50 procedures	neural
What is the bit depth capacity of the human eye	32

Created by: rad123

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