COMPREHENSIVE EQUIPMENT OPERATION AND QUALITY CONTROL

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Which of the following will improve the spatial resolution of image-intensified images?

1. A very thin coating of cesium iodide on the input phosphor
2. A smaller-diameter input screen
3. Increased total brightness gain

1. A very thin coating of cesium iodide on the input phosphor
2. A smaller-diameter input screen

Which of the following will result as tube current increases?

A. An increase in x-ray photon quality
B. An increase in x-ray photon quantity
C. A decrease in x-ray photon quality
D. A decrease in x-ray photon quantity

B. An increase in x-ray photon quantity

Patient dose during fluoroscopy is affected by the

1. distance between the patient and the input phosphor.
2. amount of magnification.
3. tissue density.

1. distance between the patient and the input phosphor.
2. amount of magnification.
3. tissue density.

The x-ray tube in a computed tomographic (CT) imaging system is likely to be associated with

1. a pulsed x-ray beam.

2. high production of heat units.

3. high-speed anode rotation.

1. a pulsed x-ray beam.

2. high production of heat units.

3. high-speed anode rotation.

Moving the image intensifier closer to the patient during fluoroscopy

1. decreases the source-image distance (SID).
2. decreases patient dose.
3. improves image quality.

1. decreases the source-image distance (SID).
2. decreases patient dose.
3. improves image quality.

Disadvantages of moving grids over stationary grids include which of the following?

1. They can prohibit the use of very short exposure times.
2. They increase patient radiation dose.
3. They can cause phantom images when anatomic parts parallel their motion.

1. They can prohibit the use of very short exposure times.
2. They increase patient radiation dose.

Fractional-focus tubes, with a 0.3-mm focal spot or smaller, have special application in

A. magnification radiography.
B. fluoroscopy.
C. tomography.
D. image intensification.

A. magnification radiography.

As the image intensifier's FOV is reduced, how is the resulting image affected?

1. Magnification increases
2. Brightness decreases
3. Quality increases

1. Magnification increases
2. Brightness decreases
3. Quality increases

When the radiographer selects kilovoltage on the control panel, which device is adjusted?

A. Step-up transformer
B. Autotransformer
C. Filament circuit
D. Rectifier circuit

B. Autotransformer

If a radiograph were made of an average-size knee using automatic exposure control (AEC) and all three photocells were selected, the resulting radiograph would demonstrate

A. excessive density.
B. insufficient density.
C. poor detail.
D. adequate exposure.

B. insufficient density.

A slit camera is used to measure

1. focal spot size.
2. intensifying-screen resolution.
3. SID resolution.

1. focal spot size.

...

The radiographic image in the figure below was obtained while testing timer accuracy in a three-phase x-ray machine.

D. Tungsten

Of what material is x-ray tube component number 5 in the figure below made?

A. Cesium
B. Copper
C. Molybdenum
D. Tungsten

Which of the following combinations would deliver the least amount of heat to the anode of a 3-phase, 12- pulse x-ray unit?
A. 400 mA, 0.12 second, 90 kVp
B. 300 mA, 1/2 second, 70 kVp
C. 500 mA, 1/30 second, 85 kVp
D. 700 mA, 0.06 second, 120 kVp

C. 500 mA, 1/30 second, 85 kVp

*Three-phase, six-pulse HU are determined from the product of mA x time x kVp x 1.35.
*Three-phase, 12-pulse HU are determined from the product of mA x time x kVp x 1.41.

Which of the following formulas would the radiographer use to determine the total number of HU produced with a given exposure using three-phase, six-pulse equipment?

A. mA x time x kVp
B. mA x time x kVp x 3.0
C. mA x time x kVp x 1.35
D. mA x time x kVp x 1.41

C. mA x time x kVp x 1.35

If exposure factors of 85 kVp, 400 mA, and 0.12 second yield an output exposure of 150 mR, what is the mR/mAs?

A. 0.32
B. 3.1
C. 17.6
D. 31

B. 3.1

*(150 mR ÷ mAs = 3.1 mR/mAs).

Which of the following combinations would pose the most hazard to a particular anode?

A. 0.6 mm focal spot, 75 kVp, 30 mAs
B. 0.6 mm focal spot, 85 kVp, 15 mAs
C. 1.2 mm focal spot, 75 kVp, 30 mAs
D. 1.2 mm focal spot, 85 kVp, 15 mAs

A. 0.6 mm focal spot, 75 kVp, 30 mAs

C. Molybdenum

Of what material is x-ray tube component number 2 in the figure below made?

A. Cesium
B. Copper
C. Molybdenum
D. tungsten

In which of the following examinations would a cassette front with very low absorption properties be especially important?

A. Abdominal radiography
B. Extremity radiography
C. Angiography
D. Mammography

D. Mammography

Capacitor discharge mobile x-ray units

1. use a grid-controlled x-ray tube.
2. are typically charged before the day's work.
3. provide a direct current output.

1. use a grid-controlled x-ray tube.

3. provide a direct current output.

Which of the following contribute(s) to inherent filtration?

1. X-ray tube glass envelope
2. X-ray tube port window
3. Aluminum between the tube housing and the collimator

1. X-ray tube glass envelope
2. X-ray tube port window

The voltage ripple associated with a three-phase, 12-pulse rectified generator is about

A. 100%.
B. 32%.
C. 13%.
D. 3%.

D. 3%.

Which of the following functions to increase the mA?

A. Increase in charge of anode
B. Increase in heat of the filament
C. Increase in kVp
D. Increase in focal spot size

B. Increase in heat of the filament

...

The number 2 in the figure below indicates the effective focal spot.

In fluoroscopy, the automatic brightness control adjusts the

A. kVp and mA.
B. backup timer.
C. mA and time.
D. kVp and time.

A. kVp and mA.

An automatic exposure control device can operate on which of the following principles?

1. A photomultiplier tube charged by a fluorescent screen
2. A parallel-plate ionization chamber charged by x-ray photons
3. Motion of magnetic fields inducing current in a conductor

1. A photomultiplier tube charged by a fluorescent screen
2. A parallel-plate ionization chamber charged by x-ray photons

The input phosphor of the image intensifier tube functions to convert

A. kinetic energy to light.
B. x-rays to light.
C. electrons to light.
D. fluorescent light to electrons.

B. x-rays to light.

A photostimulable phosphor plate is used with

A. computed radiography (CR).
B. radiographic intensifying screens.
C. fluoroscopic intensifying screens.
D. image intensified fluoroscopy.

A. computed radiography (CR).

Using a multifield image intensifier tube, which of the following input phosphor diameters will provide the best spatial resolution?

A. 35 cm
B. 25 cm
C. 17 cm
D. 12 cm

D. 12 cm

A spinning top device can be used to evaluate

1. timer accuracy.
2. rectifier failure.
3. the effect of kVp on contrast.

1. timer accuracy.
2. rectifier failure.

The advantages of capacitor discharge mobile x-ray equipment include

1. compact size.
2. light weight.
3. high kVp capability.

1. compact size.
2. light weight.

Which of the following terms describes the amount of electric charge flowing per second?

A. Voltage
B. Current
C. Resistance
D. Capacitance

B. Current

The most commonly used types of AEC devices are the

1. ion chamber.
2. photomultiplier tube.
3. cathode ray tube.

1. ion chamber.
2. photomultiplier tube.

The total number of x-ray photons produced at the target is contingent on the

1. tube current.
2. target material.
3. square of the kilovoltage.

1. tube current.
2. target material.
3. square of the kilovoltage.

The part of a CT imaging system made of thousands of solid-state photodiodes is the detector array

...

Which of the following circuit devices operate(s) on the principle of self-induction?

1. Autotransformer
2. Choke coil
3. High-voltage transformer

1. Autotransformer
2. Choke coil

A. Anode stem

What x-ray tube component does the number 5 in the figure below indicate?
A. Anode stem
B. Rotor
C. Stator
D. Focal track

In which type of equipment does kVp decrease during the actual length of the exposure?

1. Condenser discharge mobile equipment
2. Battery-operated mobile equipment
3. Fixed x-ray equipment

1. Condenser discharge mobile equipment

The line focus principle refers to the fact that

A. the actual focal spot is larger than the effective focal spot.
B. the effective focal spot is larger than the actual focal spot.
C. x-rays travel in straight lines.
D. x-rays cannot be focused.

A. the actual focal spot is larger than the effective focal spot.

A. Number 1

Which of the x-ray circuit devices seen in the figure below operates on the principle of self-induction?
A. Number 1
B. Number 2
C. Number 3
D. Number 7

To maintain image clarity, the path of electron flow from photocathode to output phosphor is controlled by

A. the accelerating anode.
B. electrostatic lenses.
C. the vacuum glass envelope.
D. the input phosphor.

B. electrostatic lenses.

Dedicated radiographic units are available for

1. chest radiography.
2. head radiography.
3. mammography.

1. chest radiography.
2. head radiography.
3. mammography.

As the CR laser scanner recognizes various tissue densities, it constructs a graphic representation of pixel value distribultion called a

A. processing algorithm
B. histogram
C. lookup table
D. exposure index

B. histogram

Double-focus x-ray tubes have two

1. focal spots.
2. filaments.
3. anodes.

1. focal spots.
2. filaments.

The image intensifier's input phosphor differs from the output phosphor in that the input phosphor

A. is much larger than the output phosphor.
B. emits electrons whereas the output phosphor emits light photons.
C. absorbs electrons whereas the output phosphor absorbs light photons.
D. is a fixed size, and the size of the output phosphor can

A. is much larger than the output phosphor.

The advantages of large format spot film cameras, such as 100 mm and 105 mm, over smaller format cameras, such as 70 mm and 90 mm, include

1. improved image quality.
2. decreased patient dose.
3. decreased x-ray tube heat load.

1. improved image quality.

The brightness level of the fluoroscopic image can vary with

1. milliamperage.
2. kilovoltage.
3. patient thickness.

1. milliamperage.
2. kilovoltage.
3. patient thickness.

X-ray tube life may be extended by

1. using low-mAs/high-kVp exposure factors.
2. avoiding lengthy anode rotation.
3. avoiding exposures to a cold anode.

1. using low-mAs/high-kVp exposure factors.
3. avoiding exposures to a cold anode.

The line focus principle expresses the relationship between

A. actual and effective focal spot.
B. SID used and resultant density.
C. exposure given the IR and resultant density.
D. kilovoltage used and the resulting contrast.

A. actual and effective focal spot.

All of the following are associated with the anode except

A. the line focus principle.
B. the heel effect.
C. the focal track.
D. thermionic emission.

D. thermionic emission.

Which of the following combinations would pose the least hazard to a particular anode?

A. 1.2-mm focal spot, 92 kVp, 1.5 mAs
B. 0.6-mm focal spot, 80 kVp, 3 mAs
C. 1.2-mm focal spot, 70 kVp, 6 mAs
D. 0.6-mm focal spot, 60 kVp, 12 mAs

A. 1.2-mm focal spot, 92 kVp, 1.5 mAs

Radiographs from a particular three-phase, full-wave-rectified x-ray unit, made using known correct exposures, were underexposed. A synchronous spinning top test was performed using 200 mA, 1/12 second, and 70 kVp, and a 20° arc is observed on the test film. Which of the following is most likely the problem?

A. The 1/12-second time station is inaccurate.
B. The 200-mA station is inaccurate.
C. A rectifier is not functioning.
D. The processor needs servicing.

A. The 1/12-second time station is inaccurate.

Congruence of the x-ray beam with the light field is tested using

A. a pinhole camera.
B. a star pattern.
C. radiopaque objects.
D. a slit camera.

C. radiopaque objects.

When a spinning top is used to test the timer efficiency of full-wave-rectified single-phase equipment, the result is a series of dots or dashes, with each dot representing a pulse of radiation. With full-wave-rectified current and a possible 120 dots (pulses) available per second, one should visualize 12 dots at 1/10 second, 6 dots at 0.05 second, 10 dots at 1/12 second, and 3 dots at 0.025 second. Because three-phase equipment is at almost constant potential, a synchronous spinning top must be used for timer testing, and the result is a solid arc (rather than dots). The number of degrees covered by the arc is measured and equated to a particular exposure time.

The radiograph illustrated in the figure below was made using a single-phase, full-wave-rectified unit with a timer and rectifiers that are known to be accurate and functioning correctly. What exposure time was used to produce this image? 0.05 second

What is the relationship between kilovoltage (kV) and the half-value layer (HVL)?

A. As kV increases, the HVL increases.
B. As kV increases, the HVL decreases.
C. If the kV is doubled, the HVL doubles.
D. If the kV is doubled, the HVL is squared.

A. As kV increases, the HVL increases.

A focal spot size of 0.3 mm or smaller is essential for which of the following procedures?

A. Bone radiography
B. Magnification radiography
C. Tomography
D. Fluoroscopy

B. Magnification radiography

The instrument that is frequently used in quality control programs to measure varying degrees of x-ray exposure is the

A. aluminum step wedge.
B. spinning top.
C. densitometer.
D. sensitometer.

C. densitometer.

Using a multifield image intensifier tube, which of the following input phosphor diameters will provide the greatest magnification?

A. 35 cm
B. 25 cm
C. 17 cm
D. 12 cm

D. 12 cm

If 85 kV and 20 mAs were used for a particular abdominal exposure with single-phase equipment, what mAs would be required to produce a similar radiograph with 3-phase, 12-pulse equipment.

A. 40
B. 25
C. 20
D. 10

D. 10

Which of the following voltage ripples is (are) produced by single-phase equipment

1. 100% voltage ripple
2. 13% voltage ripple
3. 3.5% voltage ripple

1. 100% voltage ripple

With single-phase, full-wave-rectified equipment, the voltage drops to zero every 180° (of the AC waveform); that is, there is 100% voltage ripple. With three-phase equipment, the voltage ripple is significantly smaller. Three-phase, 6-pulse equipment has a 13% voltage ripple, and three-phase, 12-pulse equipment has only a 3.5% ripple. Three-phase, 12-pulse equipment comes closest to constant potential, as the voltage never falls below 96.5% of maximum value.

If the primary coil of the high-voltage transformer is supplied by 220 V and has 200 turns, and the secondary coil has 100,000 turns, what is the voltage induced in the secondary coil?

A. 40 kV
B. 110 kV
C. 40 V
D. 110 V

B. 110 kV

Which of the following causes pitting, or many small surface melts, of the anode's focal track?

A. Vaporized tungsten on the glass envelope
B. Loss of anode rotation
C. A large amount of heat to a cold anode
D. Repeated, frequent overloading

D. Repeated, frequent overloading

Which of the following combinations will present the greatest heat-loading capability?

A. 17° target angle, 1.2-mm actual focal spot
B. 10° target angle, 1.2-mm actual focal spot
C. 17° target angle, 0.6-mm actual focal spot
D. 10° target angle, 0.6-mm actual focal spot

B. 10° target angle, 1.2-mm actual focal spot

The smaller the focal spot, the more limited the anode is with respect to the quantity of heat it can safely accept. As the target angle decreases, the actual focal spot can be increased while still maintaining a small effective focal spot. Therefore, group B offers the greatest heat-loading potential, with a steep target angle and a large actual focal spot. It must be remembered, however, that a steep target angle increases the heel effect, and film coverage may be compromised.

A. Figure a.

Which of the illustrations in the figure below depicts the ionization-chamber type of automatic exposure control?

A. Figure a.
B. Figure b.
C. Both are ionization-chamber-type AEC.
D. Neither is ionization-chamber-type AEC.

The ability of an x-ray unit to produce constant radiation output, at a given mA, using various combinations of mAs and time is called

A. linearity.
B. reproducibility.
C. densitometry.
D. sensitometry.

A. linearity.

The batteries in battery-operated mobile x-ray units provide power to

1. the x-ray tube.
2. machine locomotion.
3. the braking mechanism.

1. the x-ray tube.
2. machine locomotion.
3. the braking mechanism.

The device used to test the accuracy of the x-ray timer is the

A. densitometer.
B. sensitometer.
C. penetrometer.
D. spinning top.

D. spinning top.

The effective energy of the x-ray beam is increased by increasing the

1. added filtration.
2. kilovoltage.
3. milliamperage.

1. added filtration.
2. kilovoltage.

Double-focus x-ray tubes have two

A. port windows.
B. anodes.
C. filaments.
D. rectifiers.

C. filaments.

With mAs adjusted to produce equal exposures, all of the following statements are true except

A. A single-phase examination done at 10 mAs can be duplicated with 3-phase, 12-pulse at 5 mAs.
B. There is greater patient dose with three-phase equipment than with single-phase equipment.
C. Three-phase equipment can produce comparable radiographs with less heat unit (HU) buildup.
D. Three-phase equipment produces lower-contrast radiographs than single-phase equipment.

B. There is greater patient dose with three-phase equipment than with single-phase equipment.

C. line focus principle.

The figure below illustrates the:
A. anode heel effect.
B. reciprocity law.
C. line focus principle.
D. inverse square law.

Which of the following techniques is used to evaluate the dynamics of a part?

A. Fluoroscopy
B. Stereoscopy
C. Tomography
D. Phototiming

A. Fluoroscopy

Exposures less than the minimum response time of an AEC may be required when

1. using high mA.
2. using fast film-screen combinations.
3. examining large patients or body parts.

1. using high mA.
2. using fast film-screen combinations.

All the following x-ray circuit devices are located between the incoming power supply and the primary coil of the high-voltage transformer except

A. the circuit breaker.
B. the kilovoltage selector.
C. the rectifiers.
D. the autotransformer.

C. the rectifiers.

Anode angle will have an effect on the

1. severity of the heel effect.
2. focal spot size.
3. heat load capacity.

2. focal spot size.

Accurate operation of the AEC device is dependent on

1. the thickness and density of the object.
2. positioning of the object with respect to the photocell.
3. beam restriction.

2. positioning of the object with respect to the photocell.
3. beam restriction.

Which of the following waveforms has the lowest percentage voltage ripple?

A. Single-phase
B. Three-phase, 6-pulse
C. Three-phase, 12-pulse
D. High-frequency

D. High-frequency

Circuit devices that will conduct electrons in only one direction are

1. resistors.
2. valve tubes.
3. solid-state diodes.

2. valve tubes.
3. solid-state diodes.

A device used to ensure reproducible radiographs, regardless of tissue density variations, is the

A. phototimer.
B. penetrometer.
C. grid.
D. rare earth screen.

A. phototimer.

C. To direct electrons to the focal track

What is the function of x-ray tube component number 2 in the figure below?

A. To release electrons when heated
B. To release light when heated
C. To direct electrons to the focal track
D. To direct light to the focal track

Which of the following equipment is mandatory for performance of a myelogram?

A. Cine camera
B. 105-mm spot film
C. Tilting x-ray table
D. Tomography

C. Tilting x-ray table

With three-phase equipment, the voltage across the x-ray tube

1. drops to zero every 180°.
2. is 87% to 96% of the maximum value.
3. is at nearly constant potential.

2. is 87% to 96% of the maximum value.
3. is at nearly constant potential.

Light-sensitive automatic exposure control devices are known as

A. phototimers.
B. ionization chambers.
C. sensors.
D. backup timers.

A. phototimers.

A parallel-plate ionization chamber receives a particular charge as x-ray photons travel through it. This is the operating principle of which of the following devices?

A. Automatic exposure control
B. Image intensifier
C. Cine film camera
D. Spot film camera

A. Automatic exposure control

As electrons impinge on the target surface, less than 1% of their kinetic energy is changed to

A. x-rays.
B. heat.
C. gamma rays.
D. recoil electrons.

A. x-rays.

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