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Equipment Op & QC

Radiation Equipment Operation & QC

Which of the following can the output phosphor on the Image Intensifier be coupled to the Vidicon TV camera, or CCD (Charge Coupled Device) with....Fiber Optics, Image Distributor (Lens), Closed Circuit TV? Fiber Optics & Image Distributor (Lens).
To produce an equal exposure on 3 phase 12 pulse equipment that's comparable to single phase equipment, how would I change the exposure factors if only changing the mAs? For 3 phase 6 pulse? Why is this? I can reduce the mAs by 50%. I can reduce the mAs by 1/3. Because 3 phase equipment has a higher effective kilovoltage.
Which of the following operate on Mutual induction.....Autotransformer, High Voltage transformer, Filament transformer? On Self Induction? High Voltage transformer & Filament transformer operate on mutual induction. Autotransformer operates on self induction.
Which of the following does a double focus x-ray tube have.....Filament, Anode, Focal spots? Double focus x-ray tube has 2 filaments (large & small) & 2 focal spots (large & small).
What material is the focusing cup made of? Molybdenum
What does the rectification system do? Changes alternating current (AC) to unidirectional current.
If an examination of a particular body part required the use of only the center cell & all 3 cells were selected with AEC, what would happen with the exposure? Why is this? How would this affect density on the radiograph? The exposure would terminate early. The scatter from the body part would reach the outer cells & turn off the exposure prematurely. There would be insufficient density on the radiograph.
How much keV would be needed in an electron to eject a K shell electron from a Tungsten atom in the anode target? What type of radiation is this? How much of the primary beam does this type of radiation make up? 70 keV. Characteristic radiation. About 15%.
What can the spinning top test be used to evaluate in single phase equipment? What is it used to evaluate in 3 phase equipment? Timer accuracy, or rectifier efficiency in single phase equipment? To evaluate timer accuracy.
Beam alignment must be accurate to what % of the SID? So if the SID is 60", what must the collimator be accurate to? X-ray beam alignment must be accurate to 2 % of SID. 2% of 60", which is 1.2".
How much voltage ripple (voltage drop) do the following generators current have....Single phase, 3 phase 6 pulse, 3 phase 12 pulse, High frequency? What % of maximum value is the voltage across the x-ray tube during 3 phase? Single phase 100%, 3 phase 6 pulse 13%, 3 phase 12 pulse 4%, High frequency less than 1%. 87%-96%
What does the autotransformer control? Controls/Selects the amount of voltage to sent to the primary winding of the step up (high voltage) transformer.
Which side is focal spot blur greatest at.....cathode end, anode end? Which side is the projected focal spot greatest at? Focal spot blue is greatest at the cathode end. The projected focal spot is greatest at the the cathode end.
What is the type of x-ray tube that's designed to turn on & off rapidly, providing multiple short precise exposures? Where is the device that allows for the turning the current on & off? A grid controlled x-ray tube. The focusing cup is used as the electronic grid.
What is the minimum response time, or minimum reaction time of an AEC? The length of the shortest exposure possible with a particular AEC.
Which part of the cathode receives low voltage current? What is the low voltage for? Which part receives high voltage current? The cathode filament receives low voltage current to heat it for thermionic emission. High voltage is applied to drive electrons across to the focal track.
If kV is increased, is the HVL also increased? Why?Do kV & HVL have a direct, or indirect relationship? As kV increases, HVL also increases. The greater the intensity of the beam, the greater the HVL required to cut the intensity in half. kV & HVL have a direct relationship.
What is the type of mobile x-ray unit that's kV gradually decreases throughout the length of the exposure? A capacitor discharge unit.
Which of the following are advantages of a capacitor discharge mobile unit.....compact size, light weight, high kV capability? Compact size & light weight
Which of the following affect patient dose during fluoroscopy.....OID (distance between patient & input phosphor), amount of magnification, tissue density? All of them.
Why is patient dose increased with increased tissue density during fluoroscopy.? As tissue density increases, greater exposure dose is required.
Which of the following devices converts electrical energy into mechanical energy......Motor, Generator, Stator, Rotor? The motor
Which of the following is a slit camera used to measure.....Focal spot size, Spatial resolution, Intensifying screen resolution? Focal spot size & spatial resolution.
Is the TV part of the Image Intensifier? What does it do? No. It displays the image that is transmitted from the output phosphor.
When selecting kV on the control panel, which device is adjusted? The autotransformer
Which of the following are Star & Wye configurations related to....Autotransformer, 3 phase transformer, rectification system, AEC? With the configuration of transformer windings in 3 phase equipment.
What is the device that directs light emitted from the image intensifier to various viewing & imaging apparatus? A beam splitter
Is the high voltage transformer considered to be a component part of the CT gantry? Yes
What does repeated, frequent overloading of exposures of unsafe values cause to the anode's focal track? pitting, or many small surface melts.
What does an exposure of a large amount of heat to a cold anode do? Why is this? It can cause cracking in the anode. The anode may not have enough time to disperse the heat.
What is the formula for Heat Units (HU) for single phase? What are the correction factors used for 3 phase 6 pulse & 3 phase 12 pulse? What % increase is the intensity of the beam? HU = mA x Sec x kV. 3 phase 6 pulse 1.35 (35%) & 3 phase 12 pulse 1.41 (41%).
How is congruence of the x-ray beam with the light field tested? A radiopaque object placed in the corner of the light field.
Which of the following is not located between the incoming power supply & the primary coil of the high voltage transformer....timer, kV meter, mA meter, autotransformer? Where is it located? The mA meter. At the midpoint of the 2ndry coil of the high voltage transformer.
Which of the following do Capacitor-Discharge mobile x-ray units use capacitors to power....x-ray tube, machine locomotion, braking mechanism? The x-ray tube
Does the x-ray tube in a CT imaging system use a pulsed x-ray beam? Yes.
Which of the following information is needed to determine the maximum safe kV using the appropriate x-ray rube rating chart.......mA & exposure time, Focal spot size, Imaging system speed? mAs & focal spot size.
What is the term that's used to change alternating current (AC) into unidirectional current? What is used to do this & what are they made of & what do they do? Rectification. A solid state diode. Semi conductors made of Silicon, Selenium, or Germanium. They conduct electricity in only 1 direction.
How much distance should the light bulb be from the center of the mirror in the collimator's? The same distance as the focal spot from the mirror.
Which of the following would best correct overexposure using AEC because an exposure shorter than the minimum response time was required.......decrease mA, use minus density, use plus density, decrease kV? Decreasing mA.
Are capacitor discharge mobile x-ray units typically charged before a days work, or just before an exposure is made? Why is this? Just before an exposure is made. Because the charge tends to leak away.
Which mobile unit is lighter & fairly easy to maneuver....capacitor discharge unit, or battery powered? Which one needs to be charged more often? Capacitor discharge unit. The capacitor discharge unit.
In regards to Image Intensifiers, will the smaller input phosphor, or larger input phosphor increase patient dose? The smaller input phosphor.
Where do the electrons in the cathode end of the tube originate from? Where does the electron cloud originate from? The electrons originate from the filament. The electron cloud originated from the focusing cup.
Is a Detector Element the same as a pixel? Is the entire DEL recording incoming remnant radiation? No. No.
Which selects the size of the filament......focal spot, or mA? Focal spot
Which of the following functions to increase the mA.......increase charge of anode, increase heat of filament, increase in kV, increase of focal spot size? Increase in heating of filament.
What do fractional focus tubes with a 0.3 mm focal spot, or smaller have a special application in? Magnification radiography
Why is an autotransformer also called a variable transformer? It is where the kVp is varied.
What type of x-ray machine uses a continually decreasing mA for shortest exposure times possible? Why does the mA continually drop? Falling load generator. When the maximum heat load for an mA selection has been reached, the generator drops the mA to the next lower level the machine can handle.
When performing a QC test to ensure that adjacent mA stations are accurate, the results must be within what % of each other? Within 10%
When a QC test is performed to ensure that the same exposure factors produce consistent x-ray output, successive exposures must be within what % of each other? Within 5%
When performing a QC test to to ensure that penetrating ability of the x-ray beam is accurate, the result must be within what of the control panel setting? So if the kVp selected is 65 kVp, what must the range be? Within 4 kVp. 61-69 kVp.
What is the names of the feature of the image intensifier that automatically adjusts kVp & mAs during fluoroscopy? Does the patient dose vary with this? Is the image quality maintained? Automatic Brightness Control & Automatic Gain Control. Patient dose varies. Yes ABC maintains image quality.
What letter represents atomic mass? What letter represents the atomic #? Letter A represents atomic mass. Letter Z represents the atomic #.
What are atoms with the same # of protons, but differing numbers of neutrons? Isotopes
What is the force that holds electrons in orbit around the nucleus? Electron binding energy
What is the unit of electromotive force? What is the SI unit of electric current? The volt. Ampere.
Electrical generating stations (electrical generator) generally provide what type of current? Alternating Current (AC)
What type of current does the x-ray machine receive from the incoming line? 120-Hz AC
What is the term for the x-ray beam that leaves the anode consisting of many different energies (wavelengths)? Heterogeneous
Where in the Image Intensifier tube is electron energy converted to light? At the output phosphor.
In the Image Intensifier tube, the total brightness gain is a product of what? Minification Gain x Flux Gain = Brightness Gain
Opposing voltage created in a conductor by passing AC through it describes what? Self Induction
Inducing current flow in a 2ndry coil by varying the current flow through a primary coil describes what? Mutual Induction
Following single phase full wave rectification, the waveform contains 2 pulses per cycle, or how many pulses per second? 120 pulses per second
Which of the following would test for film screen contact......penetrometer, sensitometer, pinhole camera, wire mesh? Wire mesh tests for film screen contact
Of the following, what is a backup timer used for in AEC.......Control minimum resposne time of equipment, Limit exposure in case of equipment failure, Allow longer exposure time for extremely large patients, Control density altered by pathology. To limit exposure in case of equipment failure
Which of the following measures degrees of xray exposure by measuring different densities? Which gives precise exposure to film emulsion? Which shows the effect of kVp on contrast...Densitometer, Sensitometer, Penetrometer (Aluminum Step Wedge)? The densitometer measures varying densities. The sensitomter gives precise exposure to film emulsion. Penetrometer (Al Step Wedge) shows the effects of kVp on contrast.
What does the term Linearity mean for QC? The term Reproducibility? A given mAs value using different mA stations (with appropriate exposure time) will provide consistent intensity. Reproducibility is repeated exposures at a given technique provide consistent intensity.
Does mammography require a cassette front with very low absorption properties to be important? Why? Yes. Due to the low kVp used for mammmo the low attenuation properties of the IR front are important.
Does mammography require a cassette front with very low absorption properties to be important? Why? Yes. Due to the low kVp used for mammmo the low attenuation properties of the IR front are important.
Which of the following are are advantages of collimators over aperture diaphragms & flare cones.....Variety of field sizes available, more efficient beam restriction, better cleanup of scattered radiation? The variety of field sizes available & more efficient beam restriction are advantages of collimators over aperture diaphragms & flare cones.
In digital fluoroscopy, what is used to couple the Image Intensifier output screen for viewing on a display monitor? Charge Coupled Device (CCD)
What would incorrect alignment between the primary beam & the center of a focused grid result in? Why? Grid cutoff & insufficient radiographic density. The absorption of the primary beam is grid cutoff resulting of insufficient density.
Why are low mAs & high kVp exposure factors good for x-ray tube life? How does lengthy anode rotation contribute to x-ray tube damage? low mAs & higher kVp exposure factors produce less heat then higher mAs. When rotor is activated filament current is increased to produce the electrons.
Which of the following are rare earth phosphors that may be used in intensifying screens? Which is a phosphor & not a rare earth phosphor....Cesium Iodide, Gadolinium Oxysulfide, Lanthanum Oxybromide? Which is used in the II input phosphor? Gadolinium Oxysulfide & Lanthanum Oxybromide are used in intensifiying screens. Cesium iodide is used in the II input phosphor.
Which of the following minimizes off focus (extra focal) radiation...Avoiding very high kV, restricting the x-ray beam as close to the source as possible, using compression devices to reduce tissue thickness, avoiding extreme collimation? Mounting shutters as close to the source as possible minimizes off focus radiation.
Anode angle will have an effect on whoch of the following...severity of the heel effect, focal spot size, heat load capacity? Why? All of them. As the anode angle is decreased (made steeper)the actual focal spot increases resulting in a greater heat load capacity. With a steeper angle the anode heel effect is accentuated.
With a decreased anode angle (steeper angle) how will this affect the larger focal spot & effective focal spot? The actual focal spot becomes larger & the effective focal spot can stay the same.
Which of the following are typical components of a fluoroscopic video system & are needed to view an image from the II.....Videotape recorder, TV camera, TV monitor? TV camera & TV monitor
Would materials with high or low atomic #'s be appropriate for cassette front material? Lower atomic #'s are more appropriate for front of cassette material.
A radiograph exposed using a 12:1 ratio grid may exhibit a loss of density at its lateral edges because....SID was too great, grid failed to move during the exposure, tube was angled in the direction of the lead strips, CR was off center? SID was to great
The effect that differential absorption has on radiographic contrast of a high-subject-contrast part can be minimized by....Use of compensating filter, use of high kV factors, Increased collimation? Use of a compensating filter & the use of high kV factors
The effective energy of an x-ray beam is increased by which, added filtration, kV, mA? The effective energy is increased by added filtration.
The brightness level of the fluoroscopic image depends on which....mA, kV, patient thickness? All of them
Which of the following refer to size distortion....magnification, eleongation, foreshortening? Which refer to shape distortion? Magnification refers to size distortion. Elongation & foreshortening refer to shape distortion.
Which of the following has the most influence in forming the electron cloud....Filament, Focusing Cup, Stator, Target? Focusing cup
Is the fill factor related to the pixel, or Detector Element (DEL)? Detector Element (DEL)
Which of the following is the size of the actual focal spot determined by....mA selected, number of electrons in the cloud, size of the filament wire, potential difference within the tube? The size of the filament wire is what determines whether a small, or large focal spot is being used.
Which of the following is how kVp selection influences primary beam quality...changing the tube current, changing # of target interactions at the anode? By changing the # of target interactions at the anode.
Which of the following is each Thin Film Transistor (TFT) made of......Detector Element (DEL), Picture Element (pixel) size? Both of them
Which of the following can patient dose be reduced by....high speed film & screen combination, high grid ratio, an air gap with compensating SID change? High speed film & screen combination
With all other factors remaining constant, an increase in matrix size will do which of the following...increase pixel seize, decrease pixel size, increase resolution? pixel size will decrease & resolution will increase.
Created by: jamestkelley