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Related Flashcards
Cards In This Set
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What three things are required for x-ray production?
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1. Source of elections (mA)2. Acceleration of electrons (kVp)3. Abrupt deceleration
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From blackest to whitest, list the contrasts of structures in the body
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1. Air2. Fat3. Muscle4. Soft Tissue5. Bone
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When you take an exposure, what two actions are you controlling in the tube?
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MAs and KV(responsible for the quality, quantity and heat produced)
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Heating the filament causes what?
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Thermionic emission i.e. electron cloud
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Electrons remain as electron cloud at the cathode until _____ is applied?
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Potential difference(kVp)
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Main circuit provides a ______ at anode end which attracts electron to the anode?
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High voltage
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When KV is selected higher, the elections will go faster/slower?
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Faster
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Electrons striking the target cause what three interactions to occur? (electrons interacting with what?)
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Electrons interact with outershell, innershells, force field of nucleus
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The types of interactions between electrons (in the production of x-ray photons) depends on?
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1. kinetic electron energy (from filament to anode)2. binding energy of electron shells
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Main differences between the three types of electron interactions?
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1. outershell - only cause excitation2. both characteristic and brem x-rays are produced3. where most interactions occur
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Outershell electron interactions (3 facts)
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1. e that strike outer shell e have enough energy to excite them but not to ionize them 2. during excitation the energy is give off as Infrared Radiation 3. Remember, heat production is directly proportional of mA therefore if you double the heat youre doubling the dose to the patient
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Inner shell electron interactions
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1. e- has enough energy to eject inner shell electron out of atom 2. interactions with a kVp less than 70kvp are 100% BremsInteractions with 70kvp or higher are:80-90% Brems10-20% Characteristic
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Characteristic x-rays
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Occur in inner-shell interections where e- on inner shell is knocked out. A 'hole' is created and the e- from the next shell fills it in and the the e- from the next shell will fill in that hole which results in characteristic x-ray photons (cascading effect)
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The energy of a characteristic photon being produced is defined by
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Energy is equal to the difference in the binding shell energy of the two shells of which the electron dropped
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Describe the 'cascading effect'
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During characterisitic x-ray production an innershell e- is knocked out of the shell creating a hole which an e- from the next outer shell will fill. the hole on that shell will be filled by an e- from the nextmost outer shell until eventually only the outermost shell is missing an electron
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