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Exposure Factors
Chapter 5 - the Xray Tube
| Question | Answer |
|---|---|
| The physical area of the focal track that is impacted | actual focal spot |
| The positive side of the x-ray tube; serves as a target surface for high-voltage electrons from the filament, conducts the high voltage from the cathode back into the x-ray generator circuitry, and serves as the primary thermal conductor. | anode |
| Consists of the anode, stator, and rotor. | anode assembly |
| Permits the calculation of the time necessary for the anode to cool enough for additional exposures to be taken | anode cooling charts |
| Due to the geometry of the angled anode target, the radiation intensity is greater on the cathode side, this is known as? | anode heel effect |
| The negative side of the xray tube; produces a thermionic cloud, conducts the high voltage to the gap between the cathode and the anode, and focuses the electron stream as it heads for the anode. | cathode |
| Consists of the filament, focusing cup, and associated wiring? | cathode assembly |
| A two-filament arrangement within the xray tube | dual-focus |
| The area of the focal spot that is projected out of the tube toward the object being radiographed | effective focal spot |
| The entire cathode and anode assembly is housed within this glass or metal structure | envelope |
| Photons that were not produced at the focal spot; also called off-focus radiation. | extrafocal radiation |
| A small coil of thin thoriated tungsten wire | filament |
| The portion of the anode where the high-voltage electron stream will impact? | focal point |
| The portion of the anode where the high-voltage electron stream will impact; describes the circular path that will be impacted by the electron beam. | focal track |
| A shallow depression in the cathode assembly designed to house the filament | focusing cup |
| A very small focal spot; usually a fraction of a millimeter in size. | fractional focal spot |
| A type of tube that quickly regulates the flow of electrons, producing x-ray photons. | grid-controlled |
| Permits the calculation of the time necessary for the housing to cool enough for additional exposures to be made. | housing cooling charts |
| Any photons that escape from the housing except at the port | leakage radiation |
| Used to reduce the effective area of the focal spot | line-focus principle |
| Photons that were not produced at the focal-spot; also called extrafocal radiation. | off-focus radiation |
| The entire cathode and anode assembly is housed within this metal structure? | protective housing |
| A guide regarding the most common technical factor combinations that can be used without overloading the tube | radiographic tube rating charts |
| An anode assembly that turns during exposure | rotating anodes |
| As kVp increases, a greater percentage of the thermionically emitted electrons are driven toward the anode | saturation current |
| As more and more electrons build up in the area of the filament, their negative charges begin to oppose the emission of additional electrons. | space charge effect |
| An anode assembly that is immobile | stationary anodes |
| The portion of the anode where the high-voltage electron stream will impact the | target |
| Provides a guide regarding the most common technical factor combinations that can be used without overloading the tube | tube rating charts |
| A structure where the primary x-ray beams exit the envelope, which allows less absorption or scatter of photons. | window |
| The parts within the cathode assembly that connect the elements of the assembly | wiring |
| A two-filament arrangement within the x-ray tube | dual focus |
| Photons that were not produced at the focal spot; also called extrafocal radiation. | off-focus |
| Photons that were not produced at the focal spot; also called off-focus radiation. | extrafocal, radiation |
| Atomic number of Molybdenum | 42 |
| The choice of metal for the source of x-ray photons because it has a high atomic number, a high melting point, and good heat conducting ability? | Tungsten |
| What is the average life of the diagnostic x-ray tube filament? | 6-9 hours |
| What is described as a shallow depression in the cathode assembly? | Focusing cup |
| Which term represents the circular path that will be impacted by the electron beam? | Focal Track |
| What is the most common diagnostic radiography target angle? | 12 degrees |
| What is the only part of the cathode or anode that is outside the vacuum of the envelope? | stator |
| What is the key function of the envelope? | maintaining vacuum |
| What must be used to fill the space between the envelope and the tube housing? | dielectric oil |
| What would be an example of how to extend tube life? | do not make repeat exposures near tube loading limits |
| Exposure Factors Chapter 5 - The X-ray Tube |
Created by:
teresachristensen
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