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RADT 334- UNIT 3
| Question | Answer |
|---|---|
| A material that can conduct an electric current or not, depending on the voltage applied across that material. | semiconductor |
| An electronic device designed to terminate x-ray exposure after properly exposing an image receptor. | AEC |
| A method of adjusting the voltage to the x-ray imaging system to a constant value, in response to changes in voltage supplied by the power company. | line compensation |
| An electrical circuit device that stores electric charge. | capacitor |
| Place in the tube circuit, connected at the center of the secondary winding of the high-voltage step-up transformer in series with the x-ray tube. This reduces the possibility of shock. | mA meter location |
| An electrical device that contains two electrodes. | diode |
| The fluctuation in the voltage applied to the x-ray tube expressed as a percentage of peak kilovoltage. | voltage ripple |
| The process of changing alternating current and voltage into direct current and voltage. | rectification |
| A type of transformer having a single winding. | autotransformer |
| The product of voltage and current; Watt. | power |
| 220 V is supplied across 1200 windings of the primary coil of the autotransformer. If 1650 windings are tapped, what voltage will be supplied to the primary coil of the high-voltage transformer? | 302.5 V |
| A kVp meter reads 86 kVp and the turns ratio of the high-voltage step-up transformer is 1200. What is the true voltage across the meter? | 71.7 volt peak |
| The supply voltage from the autotransformer to the filament transformer is 60 V. If the turns ratio of the filament transformer is 1/12, what is the filament voltage? | 5 V |
| If the current in the primary of the filament transformer was 0.5 A with a turns ratio of 1/12, what would be the filament current? | 6 amps |
| The supply to a high-voltage step-up transformer with a turns ratio of 550 is 190 V. What is the voltage across the x-ray tube? | 104.5 kV |
| Allows relatively undiminished intensity of x-rays through the tabletop. | 90/20 table |
| List the 5 major controls on the operator's console. | On/off control, kVp selection, mAs selection, time (mAs) selection, and automatic-exposure controls. |
| Purpose of the autotransformers. | to vary and control the amplitude of the voltage supplied to the high-voltage step-up transformer and the filament transformer. |
| Primary/secondary voltage relationship in autotransformers. | Direct relation to the number of turns of the transformer. |
| What the prereading kVp meter allows. | The precise adjustment of the supply voltage and monitoring the kVp before the x-ray exposure. |
| 200 mA and 1/60 of a second equals what mAs? | 3.3 |
| 600 mA and 30 milliseconds equals what mAs? | 18 |
| What is the difference between high voltage transformer and high voltage generator? | The high-voltage transformer is just one component of a high-voltage generator. |
| In order that a reverse voltage is not applied across the x-ray tube and that the tube operates most efficiently, x-ray tubes use ____ current. | direct |
| Direct current is archived in the x-ray circuit through? | rectification |
| Voltage ripple of single-phase generator. | 100% |
| Voltage ripple of three-phase, six-pulse generator. | 14% |
| Voltage ripple of three-phase, twelve-pulse generator. | 4% |
| Voltage ripple of high-frequency generator. | 1% |
| 0.7(mA)(kVp)/1000 is the equation for computing _____ power rating. | single-phase |
| (mA)(kVp)/1000 is the equation for computing ____ or ____ power ratings. | three-phase, high-frequency |
| Graph showing the cooling rate of an x-ray tube housing. | housing cooling chart |
| Radiation emitted through the x-ray tube housing (other than the primary beam). | leakage radiation |
| Measure of heat capacity (1HU=1AVs=1Ws=1J). | heat unit |
| Shroud inside the x-ray tube surrounding the cathode to concentrate electrons on the focal spot. | focusing cup |
| Anode rotation speed. | 3400 rpm or 10,000 rpm |
| Tungsten alloyed with thorium. | Thoriated tungsten |
| Cathode to anode electron flow. | x-ray tube current |
| X-ray tube capable of high speed switching. Voltage applied to the focusing cup is the switch. | grid-controlled x-ray tube |
| Method of heat transfer by a moving fluid medium(liquid or gas). | convection |
| Electron cloud in the vicinity of the filament. | space charge. |
| Three methods used to support the x-ray tube. | Floor, wall, or ceiling mounted. |
| Where thoriated tungsten would be used in a x-ray imaging system. | cathode and anode |
| When all available electrons are projected from the cathode to the anode. | saturation current |
| Why are arcing and tube failure no longer a problem in modern x-ray tube design? | heavy filaments and high capacity anodes |
| Pass an electric current to heat a conductor and cause outer-shell electrons to be released from the conductor. | thermionic emission |
| Principal cause of tube failure. | broken filament |
| What addition to the filament material prolongs tube life? | thorium |
| Why is the filament embedded in the focusing cup? | To electrostatically shape the beam |
| Why would an x-ray tube need a large focal spot? | high intensity radiation |
| Why would an x-ray tube need a small focal spot? | better spatial resolution |
| Negative side of the x-ray tube. | cathode |
| positive side of the x-ray tube | anode |
| Name 2 types of anodes. | Fixed and rotating |
| Three functions of the anode. | X-ray tube target, electrical and thermal conductor, and mechanical support. |
| How does atomic number affect the selection of anode target materials? | high atomic number=efficient x-ray production. |
| How does thermal conductivity affect the selection of anode target material? | thermal conductivity=heat dissipation |
| How does melting point affect the selection of anode target material? | melting point=heat capacity |
| How does the anode rotate inside a glass enclosure with no mechanical connection to the outside? | induction motor |
| Higher x-ray intensity on the cathode side. | Anode heel effect |
| How can anode heel effect be used advantageously? | positioning thicker anatomy on cathode side |
| Name three causes of tube failure. | cracked or pitted anode, induction motor failure, and open filament. |
| How can space charge be removed? | increase kVp |
| X-ray tube locking-in at center and at a given SID. | detent position |
| a material that transmits x-rays and appears dark on a radiograph. | radiolucent |
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