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king radr 2309
king radr 2309 unit 3
| Question | Answer |
|---|---|
| 1.the most common device used to create the high potential difference(kv) across the x-ray tube is the high tension | transformer |
| 2.the current passing between the secondary of the high tension transformer and the rectifiers is best described as a type of | high voltage(kV) AC |
| 3.a single diode in a circuit having an A.C. power source will produce a _____________wave rectified signal. | single-phase, half |
| 4.the part of the x-ray generator that supplies the high voltage necessary between the cathode and the anode is called the | main x-ray circuit |
| 5.three-phase, full wave rectified A.C. has ___________peaks in a single cycle. | 6 |
| 6.the type of unit most likely to possess the smallest voltage ripple is a | high frequency unit |
| 11.if a manual spin top test film that imaged 6 dots was taken on a properly functioning single-phase full wave rectified unit, what timer setting was employed? | 50 milliseconds |
| 12.in a stationary anode tube, the target is imbedded in an anode made of | copper |
| 13.the anode of a modern rotating anode tube is generally composed of tungsten and1.copper 2.rhenium 3.molybdeum | 2 and 3 only |
| 14.tube support system available for use in modern diagnostic imaging equipment include | overhead ceiling support versionsfloor-to-ceiling support versionsc-arm support versions |
| 16.which of following is an advantage that a rotating anode tube will have over a stationary anode tube? | increased heat dissipationhigher tube ratingsreduced roughing of the target |
| 17.the majority of heat in a modern rotating anode tube is dissipated through the | passage of radiant heat to the tube envelope |
| 18.which of the following is used to focus the high speed electron stream toward the garget of the anode? | nickle focusing cup |
| 19.in modern x-ray equipment, the device most often used for current rectification is a | solid state diode |
| 22.the selection of voltage to the high tension transformer is most commonly made by adjusting the | autotransformer |
| 23.the high amperage necessary to cause thermonic emission in the filament circuit is developed from the use of a | step-down transformer |
| 24.the type of meter that is used to measure the current(tube current) between the electrodes of an x-ray tube is the | millammeter-seconds meter |
| 25.most x-ray machines used in the united states are designed to operate on a 220 volt or 440 volt: | 60 hertz, alternating current power supply |
| 26.the control for the amount of filament current in most modern radiographic units is directly related to the | millampere selection |
| 27.the pre-reading kV meter measures the _____________on the secondary side of the autotransformer: | voltage |
| 28.a transformer with more secondary windings than pirmary windings: | has a greater secondary voltage |
| 29.the process by which alternating current is converted into pulsating direct current is termed: | rectification |
| 32.3-phase current consists of three single-phase voltage wave forms seperated by | 120 degrees |
| 33.four diodes can be used in a circuit having an A.C. power source to produce a ______________wave rectified signal. | single-phase, full |
| 34.the turn radio of an __________can be varied by selecting the number of turns between connections on a single coil. | autotransformer |
| 35.to raise the voltage higher(kVp range) than the autotransformer is capable of raising it, a _____________transformer is included in the tube circuit(mian x-ray circuit). | step-up |
| 36.the autotransformer is connected to the ___________side of the step-up transformer. | primary |
| 37.an x-ray tube operate most efficiently with ______, but the autotransformer and step-up transformer require_________. | D.C./A.C |
| 38.a___________is a device that allows current to flow in one direction only. | diode |
| 39.the main power line in a hospital is usually a_______volt, _________hertz A.C. source. | 220/60 |
| 40.the filament circuit contains a _________transformer. | step-down |
| 41.in a step-up transformer, the voltage is ___________on the secondary side than on the primary. | higher |
| 42.a line voltage compensator is incorporated into the primary circuit of a modern radiographic unit to: | maintain a constant kVp level |
| 43. the high-tension portion of a modern x-ray circuit contains all of the following components except;a. the x-ray tube cablesb. the filament selectorc. the solid state diodesd. the millammeter | b. the filament selector |
| 44. which of the following changes would be associated with a higher amount of current passing through the filament of the x-ray tube? | the selection of a hight mA station |
| 45. the high tension(step-up) transformer of a modern x-ray circuit is most closely related to the | high potential required to accelerate the electrons across the tube |
| 46. which of the followin gcomponents are likly to be found in the primary circuit of a modern x-ray unit?a. autotransformerb. timer switch c. the anode of the x-ray tube | a and b only |
| 47. the majority of components in a modern x-ray circuit are found in the primary circuit this is done to | redujce the risk from electrical shock |
| 48. in nearly all radiographic units, the high-tension transformer is located in an oil-filled tank that also houses the a. rectifiersb. filament transformerc. atuotransformer | a and b only |
| 49. all of the following are advantages of a 3-phase power supply in a modern radiographic unit excepta. shorter permitted exposuresb. higher bean qualityc. reduced scatter porductiond. highter beam intensity | c. reduced scatter production |
| 50.in a 3-phase, 12-pulse unit, rectification is accomplished by employing | 12 solid state diodes |
| 51. the main advantage of 3-phase, over single-phase(full wave) current, is that in 3-phase current, the voltage: | never drops to a zero voltage |
| 52. rectificatin is used to supress the inverse voltage associated with alternating current before it reaches the x-ray tube. this helps to | prevent the flow of electrons towards the filament |
| 53. the length of exposure(time) can be controlled automatically by an | automatic exposure controlled (AEC) system |
| 56. the x-ray equipment manufacturers put the timer on the _________side of the step-up transformer because the voltage is ___________there. | primary/ lower |
| 57. most modern three-phase radiographic units allow for exposure times as low as 1 ms of a second. the timer most commonly used for this purpose is an | electronic times |
| 60. for safety reasons, the time circuits for most modern radiographic units are located in the | primary circuit |
| 61. the use of 3-phase, radiographic units, has the advantage of ________when compared to single phase units.a. shorter exposure timer settingsb. higher milamperage settingsc. more of the beam penetrability | abc |
| 62. the main advantage of the use of a high requency generating system includes all of the following exccepta. reduced sizeb. higher efficiencyc. reduced costd. reduced radiation output | reduced radiation output |
| 63. the ripple value is the variation in voltage across the xray tube as expresesd as a percentage of the maximunm value, witha single phase system, a ripple value of ___ is considered normal | 100% |
| 64. the most common timers in use today in diagnostic radiographic equipment are called | electronic |
| 65. the sensors used in the jamority of modern automatic exposure controlled units for the detectin of the remnant(image formation) beam, consist of three or more thin | ionization chambers |
| 66. the use of a backup timer, reuqired in an automatic exposure controlled(AEC) unit, is primarily to | protect the unit and patient from inadvertent overexposures |
| 68. types of automatic exposure control systems include | phototimers, ionization chambers |
| 69. a modern fdual focus x ray tube containsa. one filamentb. two filamentsc. one anode | b and c |
| 70. a properly designed protective housing reduces the level of leakage x radiation to less than __________when operated at maximum conditions | 100mR/hr at 1 meter(3 feet) |
| 71. according tot he line focus principle, the effective focal spot is __________the actual focal sport. | smaller than |
| 72. in a modern rotating anode, the motion of the rotating disk is accomplished by the use of an | induction motor |
| 73. in a modern rotating anode x-ray tube, which of the following will coat the molybdenumdisk and serve as the focal track? | tungsten-rhenium alloy |
| 74. in a rotating anode, the molybdenum stem is a poor conductor of heat. this material helps in preventing | bearing damage of the induction motor |
| 75. in order to prevent the movement of electrons from the anode to thte cathode during the exposure cycle, the type of current employed ffor x ray tubes is | direct current |
| 76. tungsten is the primary materia sued in the formation of the | surface fo the target of a roatating anodesurface of the target of a stationary anodewire used in the helix of the x-ray tube filament |
| 77. the x-ray tube envelope is composed of a heat resistant material called | pyrex glass |
| 78. the thin, flattened surface of the x-ray tube envelope which allows for the minimum absorption of x-ray is termed the | x-ray window |
| 79. the temperature of the filament in a modern x-ray tube is directly related to the | quantity of x-ray |
| 80. the rotation speed of an anode in most single-phase x-ray units is about | 3600rpm |
| 81. the negative electrode of a x-ray tube is commonly called the | filament |
| 82. the material that is often added to a rotating anode disk to reduce surface defects and cracks is called | rhenium |
| 83. the main reason tungsten is employed as filament material in a x-ray tube is its | high meting point |
| 84. the formation of the space charge in the filament of the x-ray tube is accomplished during the ________________of the normal exposure cycle. | prep or boost state |
| 85. the filaments in most modern x-ray tubes are surrounded by metal collars which serve to | compress the electron stream |
| 86. the durability and efficiency of the tungsten filament is often improved by the addition of the metal | thorium |
| 87. the collective repulsion o f the electron cloud arround the cathode that creates an equilibrium with the rate of electron emission by the filament is termed the | space charge effect. |
| 89. what is the purpose of the window in an x-ray tube? | for the emission of primary x-rays |
| 88. radiographic examinations requiring large tube currents and using serial exposures will often employ high speed rotating anodes with rotational speeds of about | 10000rpm |
| 91. when a radiographer changes from a small to a large focal spot for an exposure, she is actually | using a larger filament |
| 92. which of the following events occurs in the first stage (prep) of a normal radiographic exposure? | filament is heated, rotation of anode |
| 93. in a modern x-ray tube, the positively-charged electrode that serves as the target for the electron stream is the | anode disk |
| 95. the principal method by which the space charge cn be increased in a modern x-ray tube is by employing a higher | mA station |
| 96. the process by which heating of the filament in the liberation of electrons in the x-ray tube is called | thermionic emission |
| 97. in nearly all modern units, the use of the large focal spot is initiated when anexposure setting above________is employed. | 300mA |
| 99. the reduction of voltage and development of high amperage by a step-down transformer occurs in the | filament portion of the circuit |
| 100. compared to a single-phase x-ray unit, a 3 phase unit using the same technical factors will create: | more x-ray photonsmore anode heat unitshigher energy photons. |
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sunhwa