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Rad Test 1
| Question | Answer |
|---|---|
| where are xrays generated? | in the xray tube |
| what produces a controlled beam of xray photons in which the amount and penetrating power of the radiation can be accurately controlled? | xray tube |
| what does the xray tube contain? | anode side (positively charged) and cathode side (negatively charged) |
| where are the anode and cathode located? | in a glass envelope |
| what are the 2 types of anodes? | rotating and stationary |
| what material is used in both types of anodes | tungsten or tungsten molybdenum alloy |
| is a anode positively charged or negatively charged? | positively charged |
| anode is made up of what? | a target which is supported by a cylindrical base |
| why is the target made of tungsten | because of the high atomic number (74) can withstand high temperatures |
| what are the 3 important functions of the anode | mechanically supports the electron target dissipates heat from the electrons hitting the target rotates so the photons are not always on the exact same spot |
| where are stationary anodes commonly found? | portable units used for equine or dental units |
| what are stationary anodes made of? | copper and tungsten |
| why is the end of the stationary anode is angled? | to direct the beam to the patient |
| how does a stationary anode dissipate heat? | it doesn't |
| where are the filaments located? | in the cathode, opposite the anode, in the focusing cup |
| are the filaments positively charged or negatively charged? | negatively charged |
| is is focusing cup positively charged or negatively charged? | slightly negatively charged |
| what causes the filaments to become hot | pressing the pre-exposure button |
| what happens to the electrons when theyre heated? | they boil off or become excited |
| when will the electrons be released to the anode? | when we reach peak excitement |
| when is a small focal spot used | when high-resolution images are required |
| why is a large focal spot used | can receive a larger current and produce more xrays |
| what is the focusing cup made up of | molydbenum |
| whys is the focusing cup a concave shape | keeps the electrons in one area and to direct them towards the tungsten target |
| what is the area that is bombarded by electrons during an exposure and from which the xray beam originates from | focal spot |
| if you decrease the angle of the target you are... | decreasing the target surface |
| what is the heel effect | variation of intensity in the beam |
| where is the beam the strongest | towards the cathode side of the beam |
| how can you use the heel effect as an advantage | putting the thicker area of the anatomical part closer to the cathode side |
| what is the actual focal spot | the area perpendicular to the surface of the target |
| what is the effective focal spot | the area that is visible through the xray tube window and directed towards the film |
| what is the penumbra effect | the blurring of an image |
| a small focal spot produces a _____ image and a large focal spot produces a _____ image | sharp, blurred |
| what happens when you increase the target angle | stationary anode, accommodates heat better, larger focal spot increasing the penumbra effect |
| what happens when you decrease the target angle | rotating anode, smaller focal spot, decreases penumbra (image more sharp) increase heel effect |
| what allows the xrays to leave the tube head and filtration of the xrays that were produced | berylliium window |
| why is the entire tube encased in a metal housing | to prevent the escape of stray radiation and to protect the glass envelop from physical damage |
| what is the tube stand | supports the tube head during an exposure |
| the glass envelope encases the _______ and ________and is evacuated to form a _______ | anode, cathode, vacuum |
| what does the control panel do? | contains all the the mechanisms and settings needed to operate the xray machine |
| what receives power from the incoming power lines and literally transforms the power to the xray tube? | transformers |
| what allows the technician to select the appropriate kilovoltage required to produce a radiograph? | autotransformers (kilovoltage selector) |
| what does the KV selector determine | the kilovoltage selector range 40kVp to 125kVp |
| what does the MA selector control | the current passing through the cathode filament |
| what is time measured in | duration in seconds or milli-seconds |
| where is the exposure button located | on the control panel or maybe a hand-held button or foot pedal |
| what does pre-exposure activate? | the filament that charges the electrons and starts the rotating anode |
| what does exposure release? | the electrons from the cathode, strikes the anode and is directed towards the patient |
| what does the collimator do? | restricts the size and shape of the primary beam and allows only the field of view that is needed for the radiograph |
| what is the main benefit of the collimator? | reduces the amount of scatter radiation |
| what does the bucky tray hold | the xray film cassette under the tabletop |
| what do calipers do? | measure the thickness of the anatomical part being radiographed |
| what are the 4 types of focal spots? | small, fine focal spot, large, broad |
| when does radiation occur | when energy is transferred through matter |
| a patient being radiographed is ________ by being exposed to the ______________ | irradiated, xray beam |
Created by:
cbutch