Exam 2 Flashcards
how many lines per inch are recommended for a stationary grid?
10-12
to increase the density of a film by using mAs what would you do?
increase mAs by 100% (double it)
when converting from low ratio to high ratio grid what would be the best to do to maintain good film quality?
increase mAs (could increase kv also, but mAs increase decreases scatter
if a film is burned out it is said to be?
too dark
why would a fixed kv technique be preferred?
contrast is consistent
what would produce the least amount of grid lines?
a moving grid
exceeding the optimal kv range while maintaining good density would yeild a film that has?
a long scale contrast
remnant radiation refers to what?
scatter rays the leave the patient and reach the grid, and primary rays that leave the patient and reach the grid
a a general rule when you xray an elderly patient what should you do to your established radiographic technique?
decrease it
what increases patient exposure?
increased mAs
if you took a lateral cervical with 66kv, 100mAs, 1 10th of a sec, at 72” FFD and it was too light but you could see structures what would you change to retake the film?
increase kv by 15%
how much mAs increase is required when you go from a non grid to a 12:1 grid technique?
5 times
in an ap lumbar film on a thin patient using 85 kv at 100 mAs with an exposure time of 1/2 a sec and you could see the structures but the film was too light how would you get a better film?
double mAs
if you took a 14 x 17 lateral lumbar film and saw the L5-S1 area was too light what would be the best thing to do?
take a 8 x 10 spot lateral and increase the mAs by 60%
if you saw a blood vessel axially on a chest film what density would it look like on film?
water
if you saw two structures with paralleling tracks of calcification overlying the articular pillars diverging superior and converging inferior, what would you be looking at?
part of the thyroid cartilage
how would you fix a grey film that you can still see structures?
double the mAs and decrease the kv by 15%
if you took a lateral cervical at 65 kv, and 10mAs without a grid and the film was too light but you can still see structures how would you fix it?
increase kv by 15%
if you took a series of ap lumbar films at different settings which would have to lowest contrast? 95 kv, 6.25 mAs 106 kv, 3.75 mAs 58 kv, 60 mAs 85 kv, 8 mAs
106 kv and 3.75 mAs (long scale, wide exposure)
if you didn’t use a grid for an ap lumbar film and adjusted the technique to maintain a good density what would be the outcome?
the film would be very grey
how would you double the density of a film using kv?
increase kv by 15%
if you compared two cervical films one taken at 40” and the other at 72” what difference would you see?
the image on the 72” film would be smaller and clearer
what would be a problem if the xray tube shifted laterally from the center of the film?
shape distortion
what is the primary purpose of a grid?
to reduce scatter radiation to the film
what increases comptons radiation?
higher kvp
what term is used when comparing the height of absorbing strips to the width of the interspacing material of a grid?
grid ratio
what is the recommended optimal kv range for an ap lumbar film?
80-90
when looking for a grid which interspacing material would you want for xraying the spine?
aluminium
what best describes back scatter?
scatter that is directly toward the tube
if you wanted to alter the film so it had more grey tones what would you do?
increase kv
what affect does a reciprocating grid have that a stationary grid does not?
it blurs out grid lines
what is recommended for a spinal film when using a stationary grid?
a 10:1 grid ratio
if you xray an elderly patient what should you do to your established radiographic technique?
decrease it
contrast between structures of different subject densities is due to which of the following?
differential absorption
which exposure technique would have the lowest contrast? 200 mas, 75 kvp 150 mas, 65 kvp 100 mas, 95 kvp 50 mas, 110 kvp
50 mas, 110 kvp (decreased contrast = increased kvp)
what best describes the effect that scatter radiation has on a film?
it causes greying of the film
which radiographic technique would demonstrate the most film grain? 70 kv, 25 mas, for 1 sec 80 kv, 50 mas, for 1/2 sec 90 kv, 100 mas, 1/4 sec 100 kv, 200 mas, for 1/8 sec
100 kv, 200mas, for 1/8 sec
the ________ is the main function of mAs
film density
if you cannot see structures because the film is too light what would you do to retake?
double mAs and increase kv by 15%
if you took a lateral cervical at 66 kv and 100 mas and you could see structures but the film was too light what would you do to retake it?
increase kv by 15%
what would most likely produce a film with the most visible grain?
a high kvp/low mas film
which scenario would provide the darkest film? 75 kv 14 mas 65 kv 14 mas 85 kv 14 mas 95 kv 14 mas
95 kv 14 mas (increased kv = increades overexposure)
how much increase in mas is needed to maintain same density when reducing the xray field from 14 x 17 to 8 x 10?
60%
what is not true about an xray beam?
the more peripheral parts of the beam causes less distortion
what are the optimal kv ranges?
cervical 75 - 85
ap lumbar 80 - 90
thoracic 85 - 95
full spine 80 - 100
a film exposed to secondary radiation will have what appearance?
it greys the film making it dark
what would result in an increase in the amount of xrays passing through the patient without interaction?
higher kv
what is the main reason that a fixed kv technique is preferred?
contrast is consistent
a film that is lighter on one side than the other would indicate?
grid cutoff
a lateral cervical film could use what that a lateral thoracic or lumbar shouldn’t?
an air gap
what decreases contrast?
decreased kv = decreased contrast
if you are xraying a young female for scoliosis what view would you use to see thoracic and lumbar segments while taking into account her breast tissue and gonads?
full spine with the patient facing the film
what anatomy in a 72 year old patient would most likely absorb the most xrays in a lumbar and pelvic film?
osteoperotic pelvis
what is the maximum recommended kv for an 8:1 grid?
90 kv
if you wanted to alter the contrast of your film so there were more grey tones what would you increase?
kv
what refers to an attenuation of part of the beam by the grid?
grid cutoff
what produces the lowest scale of contrast?
wide range between kv and mas
what would increase patient exposure?
using a 10:1 stationary grid
what is the result of decreasing mas by 1/2?
film density would be decreased?
what would cause a decrease in subject density?
disuse atrophy?
what could be a problem if your xray tube was laterally shifted from the center of the film?
shape distortion
the height of a grids lead strips compared to the width between them is called what?
grid ratio
too high of a kv will have which effect on the film?
quantum mottle
what is the relationship between kv and mas?
50% decrease in mas is equal to 15% decrease in kv
a lateral lumbar film taken at 90 kv and 100 mas and the image was too light but you could see structures what should you do to retake image?
double mas (not kv because the value is already in optimal range for lateral lumbar)
what should you do when xraying an elderly female?
decrease mas by 30-50%
xrays that exit the patient and hit the film are called what?
remnant rays
which grid is recommended for use in chiropractic offices?
focused grid
which radiographic projections should use compensating filtration?
ap thoracic, lateral thoracic, and full spine
comparing two films with constant kv and mas one taken at 40” and one at 72” what would occur?
increased density of the 40” and decreased image size of the 72”
what is the 10 day rule?
10 days after the onset of menses is the safest time for xraying a female
an accurate collimator should not allow more than ____% of the SID of light outside of the exposure field?
2%
what is most effective at reducing secondary radiation?
filtration
