exposure 3-II
1B, 2C, 3A
1) Primary Circuit A) 25,000-150,000 volts 2) Filament Circuit B) 110,220 or 440 volts 3) Secondary Circuit C) 10-12 volts
C
3-phase current consists of three single-phase voltage waveforms separated by: a) 30 degrees b) 60 degrees c) 120 degrees d) 180 degrees
A
A 3-phase, 6-pulse unit has an effective kV of about ____ of the peak kVp. a) 87% b) 64% c) 57% d) 37%
d
A line voltage compensator is incorporated into the primary circuit of a modern radiographic unit to: a) compensate for variations of the timer b) control the desired speed of the anode c) provide the desired filament charge d) maintain a constant kVp level
A
A manual exposure requiring 40mAs is desired for an image of the shoulder. What timer setting can be used to obtain this mAs value if an 800 mA station is employed? a) 50 milliseconds b) 100 milliseconds c) 500 milliseconds d) 750 milliseconds
B
A manual radiographic exposure utilizes a 300 millisecond exposure timer setting. What exposure setting should be employed it a reduction of 40% of this value is desired? a) 120 millisecond b) 180 millisecond c) 240 millisecond d) 280 millisecond
D
A patient is to be imaged using an automatic exposure controlled (AEC) exposure at 600 mA and 80 kVp. If the minimum response time is 20 milliseconds, with a backup timer setting of 200 milliseconds, which of the following mAs values is possible? 1) 12 mAs 2) 48 mAs 3) 100 mAs a) 1 only b) 2 only c) 3 only d) 1, 2, 3
d
A radiographic exposure is taken on a 3-phase 6-pulse unit. In order to maintain the same optical density using a full wave unit would require: a) an increase of about 15% of the mAs value b) a decrease of about 30% of the kVp value c) a decrease of about 15% of the kVp value d) a doubling of the mAs value
B
A radiographic exposure is taken using the 200 mA station and a 50 millisecond timer setting at 80 kVp. What amount of mAs was used during this exposure? a) 4 mAs b) 10 mAs c) 16 mAs d) 40 mAs
B
A radiographic exposure requires 24 mAs. What timer setting will result in the appropriate values using the 200 mA station? a) 20 millisecond b) 120 millisecond c) 150 millisecond d) 250 millisecond
C
A satisfactory radiograph is produced using a 3-phase, 6-pulse unit. If the same technical factors are used on a single-phase unit, the radiograph would show a: a) Higer optical density b) Less radiographic contrast c) Lower optical density d) Less focal spot blur
a
A transformer has 2000 primary and 200 secondary turns of wire. How much voltage will be induced onto the secondary side if a 200 volt primary power supply is impressed on the device? a) 20 volts b) 200 volts c) 1000 volts d) 2000 volts
b
A transformer has 60 primary and 12,000 secondary turns of wire. How much voltage will be induced on to the secondary side if a 400-volt primary power supply is impressed on the device? a) 18 kVp b) 80 kVp c) 120 kVp d) 160 kVp
C
An AEC exposure is attempted at 400 mA and 88 kVp. If the unit has minimum response time of 25 milliseconds and a back tier setting of 100 milliseconds which of the following exposures will be permitted? a) 1, 2 only b) 1, 3 only c) 2, 3 only d) 1, 2, 3
D
An automatic exposure controlled (AEC) exposure is attempted using 100 kVp on a patient with intestinal gas from an obstruction. The most likely result will be a/an: a) overpenetrated radiograph showing a low optical density b) underpenetrated radiograph showing an excessive optical density c) radiograph with excessive optical density d) radiograph with insufficient optical density
B
An automatic exposure controlled (AEC) exposure is attempted using a 400 mA station at 80 kVp. If a 4 mAs exposure is desired but the minimum response time for this unit is 20 milliseconds, what timer setting will be indicated when the exposure is attempted? a) 10 milliseconds b) 20 milliseconds c) 100 milliseconds d) 200 milliseconds
C
An automatic exposure controlled (AEC) exposure of an abdomen is taken. Which of the following s likely to occur during a second exposure after the administration of two cups of barium? a) the optical density of the image is likely to increase b) the time of the exposure is likely to increase c) the optical density of the image is likely to decrease d) the kVp seting is likely to decrease
A
An automatic exposure controlled (AEC) unit is being used to produce a radiographic PA image of the ches. Which of the following changes would be likely to increase the optical density of the image? a) use the center AEC pickup or sensor b) increase the kilovoltage setting c) use a lower density control setting d) use a longer backup timer setting
D
An exposure is made on a full-wave rectified unit. In order to maintain the same optical density for an exposure made with a 3-phase, 6-pulse radiographic unit, the mAs value employed should be decreased by about: a) 5-10% b) 15-25% c) 25-30% d) 50-55%
c
Circuit overloads occurring in sensitive components of an electrical circuit can be prevented by the use of which of the following decives? 1) Thermionic diodes 2) Fuses 3) Circuit breakers a) 1, 2 b) 1, 3 c) 2, 3 d) 1, 2, 3
D
Compared to a single-phase x-ray unit, a 3-phase unit using the same technical factors will create: 1) More x-ray photons 2) More anode heat units 3) Higher energy photons a) 1 only b) 2 only c) 3 only d) 1, 2, 3
D
During a procedure using an automatic exposure controlled decive, which of the following factors will normally increase the optical density of the image? a) An increase in the mA setting b) An increase in the kVp setting c) A decrease in the source-to-image recpetor distance d) An increase in the optical density setting
B
During an AEC exposure what is the likely result if the cassette is placed upside down in the Bucky tray? a) the resulting image will have a deficient optical density b) the resulting image will have an excessive optical density c) the resulting image will have the desired optical density d) the resulting image will possess a higher contrast
A
During an automatic exposure controlled (AEC) technique a cassette with a 400 speed image receptor is mistakenly employed instead of a 100 speed screen IR. Which of the following is likely to occur? a) A radiographic image having an excessive optical density b) A longer than expected exposure timer value c) A radiographic image having an insufficient optical density d) A shorter than expected exposure timer value
B
During an automatic exposure controlled exposure of the pelvis, the primary sensor is placed over a large pocket of gas. The resulting radiographic image is likely to: a) Have an excessive optical density b) Have an insufficient optical density c) Have a great deal of involuntary motion d) An increaed amount of focal spot blur
D
During the operation of an x-ray tue being supplied by full-wave rectified current during 50 millisecond exposure, the tube electrodes will change (reverse) polarity: a) 24 times b) 12 times c) 6 times d) no change in polarity occurs
B
For safety reasons, the timer circuits for most modern radiographic units are located in the: a) Filament Circuit b) Primary Circuit c) Secondary Circuit d) High Voltage Circuit
C
If a 200 mA, 240 milliseconds and 84 kVp exposure was used to produce an image with the desired optical density, what new time factor would produce a similar optical density using a 400 mA station and 84 kVp? a) the optical density of the image is likely to increase b) the time of the exposure is likely to increase c) the optical density of the image is likely to decrease d) The kVp setting is likely to decrease
C
In a 3 phase, 12 pulse unit, rectification is accomplished by employing: a) 4 thermionic diodes b) 6 solid state diodes c) 12 solid state diodes d) Delta and star windings
c
In a 3-phase radiographic unit, if one of the rectifiers is damanged prior to a radiographic exposure, which of the following is likely to occure? a) an image with an increased amount of focal spot blur b) an increased amount of prep time to start the exposure c) a reduced amount of optical density due to a decreased radiation output d) a increased number of anode heat units
b
In a 3-phase, 6-pulse rectified unit, how many voltage peaks are produced for each cycle of incoming line voltage? a) 3 peaks b) 6 peaks c) 9 peaks d) 12 peaks
a
In a modern x-ray circuit, the rectification of high voltage alternating current into pulsating direct current occurs between the secondary of the high-tension transformer and the: a) x-ray tube b) Solid state diodes c) autotransformer d) inverter circuit
b
In a radiographic unit, the milliammeter will register only during the activation of the: a) Boost (prep) stage of the exposure switch b) Second (exposure) stage of the exposure switch c) Both of the above d) Neither of the above
C
In modern x-ray equipment, the device most often used for current rectification is a/an: a) Modified x-ray tube b) Thermionic valve tube c) Solid state diode d) Ionization chamber
b
In nearly all modern units the use of the large focal is initiated when the an exposure setting above _____ is employed. 1) 1 second 2) 300 mA 3) 100 kVp a) 1 only b) 2 only c) 3 only d) 1, 2, 3
a
In nearly all-radiographic units, the high-tension transformer is located in an oil-filled tank that also houses the: 1) rectifiers 2) filament transformer 3) autotransformer a) 1, 2 only b) 1, 3 only c) 2, 3 only d) 1, 2, 3
C
In order to help prevent unwanted exposures, the timer on a modern diagnostic unit shall provide a/an ______ indication when a radiographic exposure is attempted. a) Thermal and tactile b) Gustatory and motor c) Audible and visible
a
In order to maintain a constant filament current as changes are made in the kilovoltage requires the use of a: a) space charge compensator b) ballistics stabilizer c) filament boost circuit d) line voltage compensator
b
In order to operate properly x-ray tube requires direct electrical connections to the: 1) Filament circuirt 2) Primary circuit 3) Secondary circuit a) 1, 2 b) 1, 3 c) 2, 3 d) 1, 2, 3
c
In the filament branch of the primary circuit, the type of meter employed to measure this current is a/an: a) Micro-ammeter b) Milliammeter c) Ammeter d) Volt meter
a
Most x-ray machines used in the US are designed to operate on a 220 volt or 440 volt: a) 60 hertz, AC power supply b) 60 hertz, DC power supply c) 120 hertz, AC power supply d) 50 hertz, DC power supply
A
Rectification is used to suppress the inverse voltage associated with alternating current before it reaches the x-ray tube. This helps to: a) Prevent the flow of electrons towards the filament b) Focus the elctron stream onto the anode c) Reduce the formation of eddy currents d) Increase the charge on the tube envelope
D
Solid state rectifiers as compared to thermionic diode have/are: 1) more durable 2) more efficient 3) longer life a) 1 only b) 2 only c) 3 only d) 1, 2, 3
C
THe use of an impulse or synchronous timer in a single-phase x-ray unit will permit accurate exposure times as short as: a) 1 ms (1/1000) b) 4 ms (1/240) c) 17 ms (1/60) d) 34 ms (1/30)
A
The accuracy of a modern electronic exposure timer of a 3 phase radiographic unit which permits exposures as low as 4 milliseconds is best evaluated using a.an: a) Oscilloscope or digital timing meter b) Thyratron or manual timing meter c) Ballistics meter or analog timing meter d) Scintillation counter or quantum timing merter
C
The control for the amount of filament current in most modern radiographic units is directly related to the: a) Timer setting selection b) Kilovoltage selection c) Milliampere selection d) Focal spot size selection
a
The current passing between the secondary of the high tension transformer and the rectifiers is best described as a type of: a) high voltage (kV) AC b) low voltage AC c) high voltage (kV) DC d) low voltage DC
B
The current produced in a high-frequency generator is accomplished be a series of high-speed switches called the: a) Inverter module b) Capacitor bank c) Thyristors d) Extinction circuit
d
The high temperatures that are needed to produce the thermionic emission in the filament of an x-ray tube require a current of about: a) 1-2 milliamps b) 3-6 milliamps c) 5-1 amp d) 4-6 amps
b
The high tension (step up) transformer of a modern x-ray circuit is most closely related to the: a) production of the high amperage needed to develop the space charge b) high potential required to accelerate the electrons across the tube c) maximum speed achieved by the rotating anode d) rate at which the x-ray photons are formed in the tube
b
The high-tension portion of a modern x-ray circuit does NOT contain which of the following componoents: a) the x-ray tube cables b) the filament selector c) the solid state diodes d) the milliammeter
B
The main advantage of the 3 phase, over single-phase (full wave) current, is that in 3-phase current, the voltage: a) never drops below the peak voltage b) never drops to a zero voltage c) is self-rectified d) is inverted
D
The main advatages of the use of high-frequency generating system does NOT include which of the following: a) reduced size b) higher efficiency c) reduced cost d) reduced radiation output
a
The main component of a line voltage compensator is a device that is capable of storing small amounts of electrical charge called a: a) capacitor/condenser b) Ballistic collector c) Wavetail reserve d) Phase converter
a
The majority of components in a modern x-ray circuit are found in the primary circuit. This is done to: a) reduce the risk from electrical shock b) decrease the size of the transformer c) reduce the size of the unit d) decrease the size of the tube housing
c
The midpoint of the high-tension transformer in a modern x-ray circuit is grounded. This serves to reduce the: a) Number of rectifiers that are required b) Storage capacity of the anode c) Amount of cable insulation d) Amount of insulating oil
c
The milliamperage that is impressed across the x-ray tube will have asubstantial effect on the: 1) Beam penetration 2) Filament Heat 3) Rate of photon production a) 1, 2 only b) 1, 3 only c) 2, 3 only d) 1, 2, 3
d
The most common device used to create the high potential difference (kilovoltage) across the x-ray tube is the high tension: a) Autotransformer b) Variable resistor c) Saturable reactor d) Transformer
B
The most common method for obtaining a fully rectified tube current involves the use of: a) two diodes (valve tubes) b) four diodes (valve tubes) c) six diodes (valve tubes) d) twelve diodes (valve tubes)
B
The most common type of rectifier for use in 3 phase radiographic equipment is the: a) Thermionic diode b) Solid state diode c) Rheostat d) Valve tube
b
The pre-reading kV meter is incorporated into the x-ray control panel to measure the potential difference on the: a) primary side of the autotransformer b) secondary side of the high tension transformer c) secondary side of the autotransformer d) filament side of the x-ray tube
d
The principle material that is used in the formulation of a solid state diode is: a) tungsten b) lanthanum c) gadolinium d) silcon
d
The process by which alternating current is converted into pulsating direct current is termed: a) Electrification b) Polarization c) Depolarization d) Rectification
c
The purpose of a ballistic-type milliampere-second meter it to measure current flow when: a) High kilovoltage settings are employed b) Low milliamperage settings are employed c) Rapid exposure time settings are employed d) Long exposure time settings are employed
C
The radiation sensors that are employed in most aurtomatic exposure controlled (AEC) units are located between the _______ and the ________. a) Tube/collimator b) Collimator/tabletop c) Tabletop/grid d) Grid/Bucky tray
c
The reduction of voltage and development of high amperage by a step-down transformer occurs in the: a) Primary portion of the circuit b) Secondary portion of the circuit c) Filament portion of the circuit d) High tension portion of the circuit
D
The ripple value is the variation in voltage across the x-ray tube as expressed as a percentage of the maximum value. With a single phase system, a ripple value of ____ is considered normal. a) 3% b) 13% c) 79% d) 100%
d
The selection of voltage to the high-tension transformer is most commonly made by adjusting the settings on the: a) exposure timer b) line voltage compensator c) filament transformer d) autotransformer
c
The selection of voltage to the primary of the high-tension transformer in a 3-phase unit is made by (a): a) Single variac b) Twin rectifier c) Three autotransformers d) Three circuit breakers
B
The sensors used in the majority of modern automatic exposure controlled units for the detection of the remnant beam, consist of three or more thin: a) Photomultipliers b) Ionization chambers c) Laser scanners d) Optical readers
A
The silicon controlled rectifier (SCR) that is often used in most modern 3 phrase or high frequency units, will normally permit exposure times as short as 1/1000 second or: a) 1 millisecond b) 5 millisecond c) 8 millisecond d) 10 millisecond
D
The small variation of the voltage waveform of 3-phase rectified current is termed the: a) Constant potential b) Phase curve c) Helix effect d) Voltage ripple
C
The termination of the radiographic exposure during an automatic exposure controlled (AEC) technique is accomplished by a device called a/an: a) LCD b) Photomultiplier tube c) Thyristor d) Cumulative timer
c
The type of meter that is used to measure the current passing between the electrodes of an x-ray tube is the: a) pre-reading kilovolt meter b) multiphasic ohm meter c) milliammeter-seconds meter d) synchronous ammeter
B
The type of unit most likely to possess the smallest voltage ripple is a: a) Full wave, single-phase unit b) 3-phase, 6- pulse unit c) Self-rectified unit d) High frequency unit
B
The use of 3-phase, radiographic units, has the advantage of __ when compared to single-phase units. 1) shorter exposure timer settings 2) higher milliamperage settings 3) more of the beam penetrability a) 1 only b) 2 only c) 3 only d) 1, 2, 3
B
The use of a backup timer, required in an automatic exposure controlled (AEC) unit, is primarily intended to: a) Improve the quality of the radiation exposing the patient b) Protect the unit and patient for inadvertent overexposures c) Enable the unit to permit multiple exposures d) Provide the means for checking the exposure accuracy
b
The use of the oil within the sealed housing of the x-ray tube is provided to: 1) increase the thermal cooling of the tube envelope 2) insure that the motor bearing of the induction motor remain lubricated 3) provide electrical insulation for the tube a) 1, 2 only b) 1, 3 only c) 2, 3 only d) 1, 2, 3
d
The voltage in the secondary circuit of a modern x-ray circuit is normally about ______ than the voltage in the primary circuit. a) 20 times lower b) 500 times lower c) 100 times higher d) 1000 times higher
D
Using an automatic exposure controlled (AEC) unit, 50 speed IR (cassette) is mistakenly employed instead of a 400 speed IR. Which of the following is likely to occur? a) the exposure time will be longer than expected b) the exposure time will be shorter than expected c) the radiograph will have an excessive optical density d) the radiograph will have insufficent optical density
A
What is the likely cause of an excessively long automatic exposure controlled (AEC) exposure? 1) The failure to properly center the x-ray tube 2) The selection of an excessive backup time 3) The selection of an excessive kVp setting a) 1 only b) 2 only c) 3 only d) 1, 2, 3
B
What is the power rating for a unit energized at 800 mA, 100 millisecond and 100 kVp? a) 8 kw b) 80 kw c) 800 kw d) 8000 kw
D
What is the shortest permitted timer setting for a full wave rectified unit using an impulse timer? a) 8 milliseconds b) 12 milliseconds c) 16 milliseconds d) 24 milleseconds
C
What is the smallest mAs value obtainable for an automatic exposure controlled (AEC) exposure using 300 mA 30 milliseconds if the unit has a minimum response time of 20 milliseconds? a) 2 mAs b) 3 mAs c) 6 mAs d) 9 mAs
c
Which component is NOT generally located in the high voltage portion of a modern x-ray circuit? a) rectifiers b) x-ray tube c) filament transformer d) Milliampere meter
c
Which of the following are NOT an advantage of a 3 phase power supply in a modern radiographic unit: a) shorter permitted exposures b) higher beam quality c) reduced scatter production d) higher beam intensity
A
Which of the following are NOT an advantage of a high frequency generator: a) a lower radiation exposure to the patient b) higher tube rating for short exposures c) an increased quality of the beam d) an increased intensity of the beam
B
Which of the following can be used to increase the optical density on a radiographic image during a normal automatic exposure controlled (AEC) exposure? 1) An increase in the backup timer 2) An increase in the density control setting 3) A decreasing in the source-to-image IR a) 1 only b) 2 only c) 3 only d) 1, 2, 3
C
Which of the following can be used to reduce involuntary mothion during an abdominal exposure if an automatic exposure controlled technique is attempted? 1) the application of a shorter backup time 2) an increaed source-to-image receptor distance 3) the use of a higher kVp setting a) 1 only b) 2 only c) 3 only d) 1, 2, 3
b
Which of the following changes would be associated with a higher amount of current passing through the filament of the x-ray tube? a) the selection of a longer timer setting b) the selection of a higher mA station c) the application of a shorter source to image distance d) the use of a kilovoltage compensation circuit
a
Which of the following components are likely to be found in the primary circuit of a modern x-ray unit? 1. Autotransformer 2. Timer switch 3. The anode of the x-ray tube a) 1, 2 only b) 1, 3 only c) 2, 3 only d) 1, 2, 3
a
Which of the following currect regulating devices are required in the production of the high-voltage direct currect needed in the x-ray production process? 1) Rectifiers 2) High-tension transformer 3) Filament transformer a) 1, 2 only b) 1, 3 only c) 2, 3 only d) 1, 2, 3
c
Which of the following devices can be used for the storage of electrical charge? a) rectifer b) transformer c) battery d) variac
C
Which of the following is a likely cause of an overload or backup time light to appear during an automatic exposure controlled (AEC) exposure? a) Failure to use the appropriate IR b) Failure to use the appropriated amount of collimation c) Failure to properly center the tube to the center of the Bucky tray d) Failure to restrain the patient during the procedure
d
Which of the following is generally found on the operating console of a x-ray machine? 1) kV control switch 2) mA control switch 3) Timer control switch a) 1 only b) 2 only c) 3 only d) 1, 2, 3
D
Which of the following types of radiographic units will permit the lowest minimum exposure timer setting? a) Half wave, single phase b) Full wave, single phase c) 3 phase (with AEC) d) 3 phase (without AEC)
C
Which of the following types of single-phase radiographic units will permit the greatest instantaneous loading capacity? a) Self-rectified current b) Half-wave rectified current c) Full wave rectified current d) Rectification is not required
A
Which type of timer is most commonly employed with most modern 3 phase radiographic units? a) Silicon controlled rectifier b) Impulse timer c) Synchronous timer d) Thyratron
C
With a grid controlled x-ray tube, the radiographic exposure is terminated when a preselected: a) Anode voltage is reached b) Cathode voltage is reached c) Grid voltage is reached d) Filament amperage is reached
C
With an alternating current source the electron flow will alternate: a) 12 times a second b) 60 times a second c) 120 times a second d) 1000 times a second
