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Chapter 6 LR
Radiographic Tube and Radiation Production
Question | Answer |
---|---|
Cathode (-) | The electrode or terminal by which current leaves an electrolytic cell (battery) |
Anode (+) | The electrode or terminal by which current enters an electrolytic cell (battery) |
Strator | A portion of a machine that remains fixed with respect to rotating parts. |
The Cathode assembly consists of.... | Filament, Focusing Cup and associated wiring. |
Filamnet | a very fine thread or fiber. |
Vaporize | turns into gas. |
Thoriated Tungsten, Rhenium and Molybdenium are materials used as Filament because.... | of their high melting point. |
Purpose of the Filament is... | to provide sufficient resistance to the flow of electrons so the heat produced will cause Thermionic Emission. |
This controls the quantity of electrons emitted. | The temperature of the filament. |
The useful life of a diagnostic x-ray tube filament will last about... | 10,000 to 20,000 exposures. |
The Anode assembly consists of.... | Anode, Stator and the Rotor. |
The Anode has 3 functions... | Serves as a target, conducts high-voltage and is the Primary thermal conductor. |
Electrons flow from... | negative (-) Cathode toward the (+) Anode side of the tube. |
Focal spot.... | The part of the anode on which the electron stream impacts. |
The size of the effective focal spot is based on .... | The angle of the target and the size of the filament. |
Heel Effect | When too small of an angle causes an unacceptable reduction in x-ray output toward the anode side of the x-ray beam. |
Focusing Cup | is used to direct the flow of electrons. |
kilovoltage (kV) | How the force applied to move the electrons in thousands of Volts. |
Potential Difference | Electrons flowing from (-) negative Cathode to (+) Anode. |
Milliamperege (mA) | The electron stream that flows between the cathode (-) and anode (+) makes up x-ray tube current. |
Tungsten is used as a filament material due to... | high melting point of 3,370 degrees C and atomic number (z) of 74 (z = 74). |
The ability of the target material to withstand heat affects both... | the quantity (mAs) and the quality (kVp) of the x-ray energy. |
Increasing the mAs will directly increase the quantity of electrons which in turn causes... | an increase in blackness on radiographic film. |
Increasing the kVp will results in.... | increased penetration (creating shorter wavelengths in x-ray w/ greater efficiency of x-ray penetration. |
Radiant Energy | When electrons are flowing at high rate of speed are decelerated or stopped suddenly at the anode & interact w/ the atoms at the target material. |
2 types of Target Interactions | Bremsstrahlung & Characteristics interactions. |
Bremsstrahlung | The energy that is lost when the electron slows down is emitted as an x-ray film. |
Characteristic | occurs only when the incoming electron interacts w/ and inner-shell electron. aka-Secondary Radiation. |
Leakage Radiation | any x-ray photons that escape from the housing except at the window or port. |
The amount of leakage radiation produced cannot exceed... | 100mR/hra/meter |
Collimator | sets of lead shutters mounted at right angles to one another limiting the area being radiated. |
Scatter Radiation occurs when... | x-rays interact w/ matter & a change in their direction results. |
Remnant Radiation | The useful radiation consisting of both primary & secondary radiation. |
Purpose of the Tube Rating Charts | to extend the life of an x-ray tube & ensure the tube can withstand the heat created by the workload. |
At any given time an x-ray tube should never exceed this many multiple exposures in a given setting. | 20 |
X-ray tube heat capacity is measured in... | HU- Heat Units |
How to calculate x-ray tube heat...HU | kVp x S x mA = |