Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
121 Unit 1
| Question | Answer |
|---|---|
| ma determines | tube current |
| current in units | amperes |
| mas and density | mas is directly proportional to density |
| time in seconds | how long it takes electrons to get to anode |
| kvp | penetrating power, force applied to push the e from cathode to anode;controls QUALITY |
| % to notice change in density | 30% |
| law of reciprocity | density should remain unchanged as long as the intensity and duration remain unchanged |
| relationship between mas and dose | directly proportional |
| relationship between kvp and dose | direct relationship |
| s# and density | inversely related; high s# underexposed, vica versa |
| inverse square law | inverse relationship between distance and dose; half the sid, 4x the exposure |
| maintaining density using kvp and mas | decrease kvp 15% and double mas |
| tool measuring optical density | densitometer |
| step wedge | penitrometer, shows gray scale on film |
| step wedge, more steps | long scale, increased kvp, decreased contrast |
| 4 radiographic properties | density contrast recorded detail and distortion |
| 4 prime technical factors | ma time kv and distance |
| geometric variables | sharpness -> (radiographic)detail and distortion |
| photographic variables | visibility (of detail) -> density and contrast |
| density | overall darkness of film, dependant on amount of exposure, must have adequate density to evaluate other qualities |
| contrast | presence or absence of shades of gray |
| more exposure | black areas, opaque |
| less exposure | white areas, translucent |
| film translucence | caused by radiopaque object |
| film density | is dependant on the # of exposed silver halide crystals |
| crystals in processor | turn into black metallic silver upon development; more crystals faster film |
| latent image | before processing |
| manifest image | after processing |
| useful range of density | .25-2.0 |
| mas and quantity | ma, # of photons produced, aka output, intensity, exposure |
| quality | kvp, penetrating ability of beam |
| Milliamperage | # of electrons crossing the tube from cathode to anode per second |
| relationship between ma and density/tube current | directly proportional |
| kvp and density | kvp has the greatest effect on density, but is not used to control density |
| 15% rule | increase kvp by 15% doubles density and vica versa |
| kvp and contrast | inverse relationship |
| to decrease contrast and maintain density | increase kvp by 15% and halve mas |
| sid | aka FFD, focal spot to film distance |
| inverse square law | intensity of radiation varies inversly with the square of the source |
| mas distance formula | to compensate for density changes with changes in sid |
| rule of thumb for sid and intensity | doubling the sid gives 1/4 the intensity, use 4x the mas; 1/2 the sid gives 4x the intensity therefore use 1/4 the mas |
| double kvp | density will increase by a factor of 4,5, or 6 |
| changes in kvp; 30-50 kvp | 5% change in kvp |
| changes in kvp; 50-90 kvp | 8% change in kvp |
| changes in kvp; 90-130 kvp | 10% change in kvp |
| aec | 1942, determines exposure time and therefore the total mas; must still set kvp, chambers and density selection |
| density selections | only way to increase or decrease density using aec; increments of -1,-2,0,+1, ect |
| phototime | didn't have ionizing chambers, only IR, flourescent screen, and photoiodide |
| fog and density | direct relationship |
| grids and density | increase grid ratio, decrease density, inverse relationship |
| screen speed and density | direct relationship |
| filtration and density | inverse relationship |
| beam restriction and density | inverse relationship |
| processing time/temp | direct relationship |
| power supply(phase) and density | direct relationship |
| patient size and density | inverse relationship |
| factors that do not effect density | motion, focal spot size, and misaligned beam |
| anode heel effect | variation in intensity of photons across longitudinal axis of beam; need more photons for thicker body part, put cathode over that part |
| anode heel effect more pronounced | with large film size and shorter sid |
| OID | aka air gap |
| oid and density | inverse relationship b/c scatter photons diverge and miss film |
| scatter and density | direct relationship |
| density and over/under development(film) | direct relationship, overdeveloped causes increase in density |
| 5 major tissue groups | aerated, fatty, water (muscle, glands), bone, teeth; from least to most dense |
| destructive pathologies and density | degrease attenuation, density increases |
| additive pathologies | increase attenuation, density decreases and requires an increase in exp. factors |
| mAs def. | the product of tube current and exposure time |
| kvp doubled | increases amount of photons 4X |
| kvp and quality | increasing the kvp increases the speed and energy of e |
| kvp and quantity | as kvp increases more interactions occur at the target |
| tissue density and IR/film density | inverse relationship |
| radioluscent contrast (air) and density | increases density |
| radiopaquse constrast media | decreases density |
| attenuation | reduction in the # of xray photons in the beam, and subsequent loss of energy, as the beam passes through matter |
| attenuation and density | inverse relationship |
| min. mas change to change density | 30% |
Created by:
sandonblaise
Popular Radiology sets