Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
62 Cards in this Set
- Front
- Back
typical kVp for angio
typical kVp for Ba |
75 for angio to maximize the vasculature
110 for ba to penetrate the Ba |
|
highest skin dose in FLX
|
500 µGy
|
|
how does minification gain affect the brightness of an image
|
if you take a lot of light and squeeze it into a smaller area makes the image brighter
the increased brightness = minification gain |
|
when are del's used
|
FPD
|
|
binning
what is it how does it affect imges |
tak e4 pixels and add them together -> 1 pixel
decreases QM |
|
how does collimation affect resoluton
|
it doesn't
|
|
how does collimating affect air kerma
|
it doesn't
|
|
how does electronic magnification affect KAP
|
it doesn't
|
|
how does electronic mag affect resolution
|
increases resolution
|
|
how does electronic mag affect air kerma
|
increases it
|
|
how does collimation affect KAP
|
decreases it
|
|
how does eletronic mag affect tube current
|
increases it
|
|
which gives more dose to pt:
FPD analog II digital II |
all the same
|
|
air kerma in AXR
|
5 µGy
|
|
air kerma in FLX spot
|
1 µGy
|
|
air kerma in last image hold
|
0.01 µGy
|
|
which improves with collimation: contrast or resolution
|
contrast (b/c less scatteR)
|
|
grid ratio in FLX
|
10:1
|
|
how does electronic mag affect resolution
|
increases it
|
|
spatial resolution of II
spatial resolution in standard TV |
4-6 lp/min
1 lp/min |
|
halving the FOB will change the spatial resolution by how much
|
2x
|
|
resolution for FPD
|
3 lp/mm
|
|
FLX of a larger pt would best reduce dose by increasing what
|
kVp (to a more penetrating beam)
|
|
what causes S distortion
|
magnetic feilds
|
|
maximum entrance air kerma rate in standard FLX
|
100 mGy/min
|
|
how many XR = 1 min of FLX for same FOV and kV
|
10 XR = 1 min FLX
|
|
XR absorption by I is maximized by using an avg energy of:
|
35 keV (just above the k-edge)
|
|
typical tube current for pulm angio
typical pulse duration for pulm angio |
300 mA
50 ms |
|
ideal skin dose for IR studies (abdomen)
|
25 mGy/min
|
|
skin dose for extremity or peds IR
|
4mGy/min + grid (or half that with grid removed)
|
|
scatter:primary ratio i nIR in neonates and extremities
in bariatric pts? |
1:1
7:1 |
|
at what thickness is a grid essential
|
>12 cm
|
|
when should you use geometric magnification in IR
|
NEVER!!!!! (-> focal spot blur, increased scatter, increased skin dose)
|
|
how does angling the XR tube affect dose
|
can triple the dose b/c you are going through more of the pt
|
|
why is skin entrance dose so impt
|
1/2 dose dielivered to the first 3-5 cm of tissue
83% of the dose is delivered to the first half of the pt entrance dose is 100X the exit dose |
|
what are the only 2 dose limits in radiology
|
100 mGy/min in FLX (not DSA)
<3mGy/image to a phantom in mammo |
|
how long does it take for skin burns to appear after IR procedure
|
10 days
|
|
minimum focus to skin distance in a fixed and mobile unit
how is this insured |
38cm
30 cm this is insured with a spacer cone |
|
sentinel event for skin dose
|
15 Gy
|
|
when converting KAP to effective dose, must account for what
|
beam quality
pt size and age region and projection |
|
what will effective dose tell you
|
cancer risk
|
|
how to convert KAP to effective dose (rule of thumb)
|
x0.1
1 Gy-cm^2 (KAP) = 0.1 mSv |
|
approx skin doses in IR
|
2 Gy
|
|
KAP in IR are ~
|
300 Gy-cm^2
|
|
maximum operator dose in IR
|
can't exceed 1mGy/hr at 1 m
|
|
air kerma rates at 1m during IR
|
~30 µGy/min
|
|
at 1m, how much dose is the operator getting
|
0.1% of skin entrance dose
|
|
type of filtration that is most commonly used in IR
|
Cu (reduces dose more than Al)
|
|
dose above hte lead apron best estimates what dose
|
eye lens
|
|
use of Pb apron reduces operator effective dose by how much
|
90%
|
|
for IR sworker, conceptus dose limit =
|
0.5 mSv/monht
|
|
legal max lifetime extremity dose
|
20 Gy
|
|
what is the problem with ambient lighting when looking at images
|
too much lighting, wont' see low contrast lesions
|
|
what is the point of adding Cu (not Al) to the beam in IR
|
that + adjusting kVp and mAs will maimize hte fraction of photons just above the i k edge
(Al doesn't have much photo-electric absorption in this region) just decreasing kVp will increase pt dose |
|
why won't only using iodine k-edge characteristic photons help to see iodinated contrast
|
I will be transparent to its own k characteristic photons b/c their energies are below the k-absorption edge
|
|
coning in during IR will have what effects
|
decreased DAP
decreased scatter improved contrast |
|
how does coning in during FLX affect spatial res
|
doesn't
|
|
end result of ABC
|
maintains contrast image brightness reaching TV camera
|
|
where are scatter levels near a pt greatest in FLX/IR
|
on the beam entrance side
|
|
best place to stand to receive lowest dose when doing intracranial aneurysm embo in lateral positioin
|
next to image receptor
|
|
IR procedure that delivers highest pt dose
|
neuroIR
|
|
what happens to dose area product if you increase the source to skin distance
|
stays the same
|