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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 |
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