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RADT 465
image production
| Question | Answer |
|---|---|
| XLEL meaning | x-rays -> light -> electrons -> light |
| what does magnification do to technical factors on image intensifiers | increases mAs, more x-rays to compensate for brightness, increases dose |
| IP sizes | 25, 17, 12, CM |
| what are IPs made of | cesium iodide |
| forumla for brightness gain | magnification gain x flux gain |
| How to decrease magnification without adjusting mag? | move II closer to pt |
| formula for pt dose | (input 1)^2/(input 2)^2 |
| formula for magnification factor | input 1/input 2 |
| What are Fluoro tables made of? | carbon fiber and polycarbonate |
| Off center grid effect | decreased of all over exposure |
| off level grid effect | decreased exposure over image due to absorption of primary photons |
| off focus grid cause | incorrect SID for grid type |
| inverted/upside down grid | decreases exposure to periphery of image |
| major drawback of AEC. | places strict requirements on positioning and selection |
| what does AEC do | allows for images to fall within an acceptable range of a mixed population of patients |
| what does the back up timer do | shuts off exposure @ 150% |
| how are bremsstrahlung x-rays made | e- from filament enters electron cloud looses energy and loops around the nucleus, x-ray given off from loss of energy |
| how are characteristic x-rays made | e- reacts with e- in e- cloud and ejects it. outer shell e- falls into place energy give off from binding energy gives off x-ray, K-shell are best |
| transformer voltage forumla | Ts/Tp= Vs/Vp |
| turns ratio formula | Ts/Tp |
| transformer current formula | Ts/Tp=Ip/Is |
| voltage ripple on three phase six pulse | 13-14% |
| voltage ripple on three phase twelve pulse | 3-4% |
| heat units correction factors | single phase- 1 3 phase 6 pulse - 1.35 3 phase 12 pulse - 1.41 high frequency - 1.45 |
| ohms law 25 | measure resistance V=IR |
| how is focal spot size tested | star pattern type, variation up to 50% od attend focal spot size |
| how are single phase exposure timers tested | spinning top, +/-5% for greater than 10ms, +/- 20 for less than 10ms |
| how are three phase exposure timers tested | digital timer,+/-5% for greater than 10ms, +/- 20 for less than 10ms |
| how is film screen contact tested | wire mess test, congruent across entire surface |
| how is light field to radiation field tested | 8/9 penny test +/-2% of SID |
| what generator types make uo most of todays x-ray equipment | 3 phase 12 pulse & high frequency |
| image intensifier components in order | input phosphor -> photo cathode -> electrostatic lenses -> anode -> output phosphor |
| what side of the x-ray circuit contains the mA selector & focal spot selector | filament circut |
| what side of the x-ray circuit contains the mA meter diode rectifiers, and electrical ground | secondary side- high voltage |
| what side of the x-ray circuit contains the pre kV meter, kV minor and major selectors, exposure switch, and exposure timer circuit | primary side, low voltage |
| what is the 15% rule? | increase in 15% of kVp requires dividing mAs by two % decreasing kV by 15% means doubling mAs |
| grid ratios | None; 1 5:1 ; 2 6:1 ; 3 8:1 ; 4 10-12:1 ; 5 16:1 ; 6 |
| what grid does air gap technique mimic | 6:1 grid |
| formula for unsharpness | (filament size x OID)/ SOD |
| what does grid usage do to patient dose | increases patient dose |
| what does SNR stand for and do you want a high to low SNR | Signal to noise ratio - high |
| what is fill factor | percentage of active area of DEL available for signal acquisition |
| as you decrease DEL size and increase matrix size what is effected | spatial resolution |
| what is VOI | recognized area within collimated field |
| forumula for HUF | number of exposures x kVp x mA x time (s) x generator factor |
| direct square law formula | (mAs 1 / mAs 2) = ((d1^2) / (d2 ^2)) |
| inverse square law formula | (I1/I2)=((d2^2) / (d1 ^2)) |
| what is intensity measured in | mR |
| forumla for mAs | mA x time (s) |
| formula for SID | SOD + OID (only one that adds) |
Created by:
kmpinkston
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