Chapter Three
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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| Alternating Current (AC) | A flow of electrons in one direction, followed by a flow in the opposite direction.
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| Anode | The positive electrode (terminal) in the x-ray tube. Tungsten block, normallyset at a 20-degree angle facing the cathode, imbedded in the copper portion of the terminal.
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| Cathode | The negative electrode (terminal) in the x-ray tube. The cathode consists of a tungstun filament wire that is set in a molybdenum focusing cup that directs the cathode stream toward the target on the anode.
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| Central Ray | The central portion of the primary beam of radiation.
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| Collimator | A diaphragm, ususally lead, designed to restrict the dimensions of the useful beam.
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| "Dead -Man" Exposure Switch | A switch so constructed that acircuit-closing contact can only be maintained by continous pressure by the operator.
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| Direct Current (DC) | Elctric current that flows continuously in one direction. Similar to current produced in batteries. Ideal for use with digital imaging.
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| Electron Cloud | A mass of free electrons that hovers around the filament wire of the cathode when it is heated to incandescence. The number of free electrons increases as the milliamperage is increased.
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| Exposure Button | Keypad or switch that activates the x-ray production process.
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| Filament | The spiral tungsten coil in the focusing cup of the cathode of the x-ray tube.
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| Filter | Absorbing material, usually aluminum, placed in the path of the beam of radiation to remove a high percentage of the low energy (longer wavelength) x-rays.
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| Focal Spot | Small area on the target on the anode toward which the electrons from the focusing cup of the cathode are directed. X-rays originate at the focal spot.
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| Focusing Cup | A curved device around the cathode wire filament that is designed to focus the free electrons toward the tungsten target of the anode.
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| Impulse | Measure of exposure time. There are 60 impulses per second.
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| Intensity | The total energy of the x-ray beam. The product of the number of x-rays (quantity) and energy of each x-ray (quality) per unit of area per time of exposure.
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| Kilovolt Peak (kVp) | The crest value in kilovolts of the potential differnece of a pulsatng generator.
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| Milliampere (mA) | One thousandth of an ampere. Milliamperage determines the number of electrons available at the filament. See Ampere.
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| Primary Beam (primary radiation of useful beam) | The original undeflected useful beam of radiation that emanates at the foacal spot of the a-ray tube and emerges through the aperture of the tube head.
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| Quality | Term used when describing the intensity of the x-ray beam. Refers to the number of x-rays in the beam.
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| Quantity | Term used when describing the intensity of the x-ray beam. Refers to the penetrating ability of the beam.
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| Target | Small block of tungsten imbedded in the face of the anode, bombarded by the electrons streaming from the cathode. The focal spot is located on teh target.
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| Thermionic Emission | The release of electrons when a material such as tungsten is heated to incandescence. Electrons are boiled off from the cathode filament in the x-ray tube when electric current is passed through it.
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| Tube Head (tube housing) | Protective metal covering that contains the x-ray tube, the high-voltage and low-voltage transformers, and insulating oil. Attached to the flexible extension arm by a yoke. The PID attaches to the tube head at the port.
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| Tungsten (Wolfram) | Element with an atomic numver of 74. High melting point makes this metal ideal for use as the cathode filament and as the anode target.
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| X-Ray Tube | Electronic tube located in the tube head that generates x-rays.
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Review the information in the table. When you are ready to quiz yourself you can hide individual columns or the entire table. Then you can click on the empty cells to reveal the answer. Try to recall what will be displayed before clicking the empty cell.
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To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
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