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RADT 334 X-ray tube
radiographic physics review covering x-ray tube
| Question | Answer |
|---|---|
| What are the three principal parts of an x-ray imaging system? | X-ray tube, control console, and high voltage generator |
| The primary purpose of the glass envelope of an x-ray tube is to: | Provide a vacuum |
| The protective housing of an x-ray tube is designed to: | Reduce the hazard of leakage radiation |
| Why is tungsten the material of choice for the target or anode? | Its atomic number, thermal conductivity, and high melting point |
| What are the two primary parts of the cathode? | A filament and a focusing cup |
| What is the most common cause of tube failure? | Tungsten vaporization with deposition on the inside of the glass enclosure |
| The _______ is the positive side of the x-ray tube; it conducts electricity and radiates heat and contains the target. | Anode |
| What is the actual x-ray source? | the focal spot |
| What principle results in an effective focal spot size much less than the actual focal spot size? | Line-focus principle |
| ______ tube currents and _______ exposure times are possible with the rotating anode. | Higher, shorter |
| What are the three methods or supporting the x-ray tube? | Ceiling support, floor support, and C-arm support |
| What are the two different types of anodes? | Stationary and rotating |
| What is the reason for the filament to be embedded in the focusing cup? | Because all of the electrons accelerated from the cathode to the anode are electrically negative, and the electron beam tends to spread out owing to electrostatic repulsion. |
| Why are x-ray tubes manufactured with two focal spots? | The small focal spot is used when better spatial resolution is required. The large focal spot is used when large body parts are imaged and when other techniques that produce high heat are required. |
| _______ is the transfer of energy from one area of an object to another. | Conduction |
| _______ is the transfer of heat by the movement of a heated substance from one place to another. | Convection |
| What effect results in a smaller effective focal spot and less radiation intensity on the anode side of the x-ray beam? | The heel effect |
| Electrons that bounce off the focal spot and then land on other areas of the target,causing x-rays to be produced from outside of the focal spot. | Off-focus radiation |
| If the _______ of the anode increases too rapidly, the anode may crack and become unstable | Temperature |
| What is the most frequent cause of abrupt tube failure? | Electron Arcing |
| What are the three different types of x-ray tube rating charts? | Radiographic rating chart, the anode cooling chart, and the housing cooling chart |
| Of the three rating charts, which is the most important? | The radiographic rating chart |
| What is the primary support structure for the x-ray tube, which allows the greatest ease of movement and range of position? | Ceiling support system |
| What are the three functions of the protective housing? | reduces leakage radiation provides mechanical support serves as a way to conduct heat away from the x-ray tube target |
| The ______ has a limited capacity for storing heat. | anode |
| The electron cloud near the filament | space charge |
| What tubes are designed to be turned on and off very rapidly? | Grid-controlled tubes |
| Most rotating anode x-ray tubes have how many filaments? | Two filaments |
| What is the melting point for tungsten? | 3400 |
| The heel effect results in ______ x-ray intensity on the anode side of the beam. | reduced |
Created by:
hmchew
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