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CH 5 RAD 150
X-Ray Imaging System
| Question | Answer |
|---|---|
| The function of the x-ray imaging system is to provide a controlled flow of ____ intense enough to produce an x-ray beam for imaging. | electrons |
| What are the three main components of an x-ray imaging system? | x-ray tube, operating console and high voltage generator |
| X-Ray systems operate at voltages of ____ - ____ kVp and tube currents of ___-___ mA. | 25-150; 100 - 1200 |
| Which radiolucent material is used for the production x-ray tables? | carbon fiber |
| The ____ _____ allows radiologic technologist to control the x-ray tube current and voltage. | operating console |
| _____ ______ refers to the number of x-rays or the intensity of the x-ray beam. | Radiation quantity |
| _____ _____ refers to the penetrability of the x-ray beam. | Radiation quality |
| Most x-ray imaging systems are designed to operate on ___ V power. | 220 |
| The voltage provided to an x-ray unit easily may vary by as much as ___%. | 5 |
| The ____ ______measures the voltage provided to the x-ray imaging system and adjusts that voltage to precisely 220 V. | line compensator |
| The power suppled to the x-ray system is delivered FIRST to the _________. | autotransformer |
| The _____ has a single winding and is designed to supply a precise voltage to the filament circuit and to the high-voltage circuit of the x-ray imaging system. | autotransformer |
| The voltage an autotransformer receives (Vp) and the voltage it provides (Vs) are _____ related to the number of turns of the transformer (Ns;Np) enclosed by the respective connections. | directly |
| What is the Autotransformer Law? | Vs/Vp=Ns/Np |
| ____ determines the quality of the x-ray beam. | kVp |
| Step up transformer ____ the voltage to the chosen kVp. | increases |
| Number of electrons emitted by the filament is controlled by _____ of the filament. | temperature |
| The x-ray tube current should always cross from ____ to ____ and is measured in ___. | cathode - anode ; milliamperes (mA) |
| The filament temperature is controlled by the filament ____ and is measured in _____. | current; amperes |
| An increase in filament current and temperature will allow more electrons to be released by _____ ____. | thermionic emission |
| Filament operate at currents of __ - __ A. | 3 - 6 |
| mAs is also _____ ____. | electrostatic charge |
| The filament transformer is a ___-___ transformer; therefore the voltage supplied to the filament is ____. | step-down; lower |
| A filament transformer steps down the V to approximately ___ V and provides current to ___ the filament. | 12; heat |
| A guard timer will terminate an exposure after approximately ___ seconds. | 6 |
| What are the four types of timers? | synchronous, electronic, mAs and AEC timers |
| Synchronous timers are based off ___ Hz. | 60 |
| _____ timers are most sophisticated, accurate and also controlled by a microprocessor. | Electronic |
| ____ determines the number of x-rays emitted and therefore the exposure of the IR. | mAs |
| The mAs timer is designed to provide the highest ____ and shortest ____. | kVp; exposure |
| ____ is used primarily for electrical insulation. | Oil |
| The ___-____ ______ increases output voltage from the autotransformer to the kVp needed for x-ray production. | high-voltage generator |
| What are the three parts to a high-voltage generator? | high voltage transformer, filament transformer and rectifiers |
| In a step-up transformer, the ____ voltage is higher than the _____ voltage, because the number of secondary windings is higher than the primary windings. | secondary; primary |
| The ratio of the number of secondary windings to the number of primary windings is called the ____ ____. | turns ratio |
| Voltage and the turns ratio is ___ proportional. | directly |
| Primary voltage is measured in ___; secondary voltage is measured in ___. | volts; kilovolts |
| Transformers operate only on _____. | AC (alternating current) |
| The turns ratio of a high voltage transformer is usually between ___ and _____. | 500:1; 1000:1 |
| Primary current is measured in ___ and secondary current is measured in ___. | amperes (A); milliamperes (mA) |
| An x-ray tube requires _____ _____. | (DC) direct current (electrons flow in only one direction) |
| ____ is the process of converting AC to DC. | Rectification |
| Electron flow is from ___ to ____. | cathode; anode (by rectification) |
| Diodes are currently known as ____-_____ ______. | solid state rectifiers |
| _____ semiconductors have loosely bound electrons that are relatively free to move. | N-type |
| ____ semiconductors have spaces, called holes, where there are no electrons. | P-type |
| During ____ rectification, current flows through the tube during the positive part of the cycle (60 pulses/second). | half-wave |
| During _______ voltage, the current that passes through the x-ray tube exists only during the positive half of the cycle when the anode is positive and the cathode is negative. | unrectified |
| Half-wave rectified circuit contains ____ diodes and passes ____ x-ray pulses/second. | 1-2; 60 |
| A form of voltage rectification that rectifies the entire AC waveform is called _______. | full-wave rectification |
| Full wave contains at least ___ diodes and current is passed through the tube ____ pulses/second. | 4; 120 |
| During three phase power, there are six pulses per _____ s. Three phase power stays ______. | 1/60; constant |
| High frequency generators result in a _____ patient dose. | decreased |
| During capacitor discharge, the voltage falls approximately ____ kV/mAs. | 1 |
| A falling load generator ensures the shortest possible _____ ____ and also decreases the ____ of the anode. | exposure time; temperature |
| Single phase power has ____% voltage ripple. | 100 |
| Three phase six pulse power produces a voltage with ___% ripple. | 14 (never falls below 86% max) |
| Three phase twelve pulse power produces a voltage with a ___% ripple. | 4 (never falls below 96% max) |
| High frequency generators produces a voltage with ___% ripple. | 1 (never falls below 99% max) |
| Power ratings is measured in _____. | kilowatts (kW) |
| A step down transformer is also known as a _____ transformer. | filament |
| Power rating (kW) = _____ x _____ | current (A); Potential (V) |
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