Review Flashcards
Dose to the fetus is approximately ___% of mom’s skin dose.
2
In a flat panel system, closer to the pt (increases/decreases) pt dose.
Increases
In a system with ABC, image intensifier, and under table tube, moving the I
image intensifier AWAY from the pt (increases/decreases) exposure.
Increases
Leakage Limit = ___ mR at 1 meter
100
Scatter exposure (mR/hr) at:
1 foot?
2 feet?
3 feet?
1 foot = 500 mR/hr
2 feet = 100 mR/hr
3 feet = 50 mR/hr
Brightness gain = ___ x ___
Minification gain x flux gain
Equation for minification gain
Input diameter squared
———————————
Output diameter squared
(In inches)
What does KERMA stand for?
Kinetic Energy Released in MAtter
What type of interaction is this?
e-i = e-d + e-p
Bremsstrahlung
A bremsstrahlung is electromagnetic radiation produced by ___ when ___.
Deceleration of a charged particle
Deflected by another charged particle
Absorbed dose in rad x Quality factor = ?
Dose equivalent in rem
Quality factor is multiplied by the ___ to produce the ___.
Absorbed dose (rad)
Dose equivalent (rem)
Major problem of vidicons?
Lag
0.25 mm lead is required when receiving what dose of radiation? (Mrad/hr)
5 mrad/hr +
What kind of contrast is determined by the kVp?
Subject
What kind of contrast is determined by the image intensifier?
Detector contrast
When magnification increases, the field of view decreases, which does what to the minification gain/ brightness?
What is the end result on pt exposure?
Lowers minification gain/brightness
Raises pt exposure
What is the term for the total number of cycles per second available for display? (Aka frequency of video signal)
Bandpass
Aka bandwidths
Equation for vertical resolution
Number horiz. lines across
——————————————
2 x diameter in mm
___ is the product of scan lines, frame rate, and frequency rate
Bandpass
What sets the overall limit to resolving power capacity of the TV?
Bandpass
Line pair grid measures what?
Resolution
lp/mm
Occupational maximum dose
10 mSv x age
General population max dose
1 mSv/yr = 0.1 rem/yr
More bit depth = more what?
Contrast resolution
You want to place the image intensifier as close to the pt as possible in order to lower pt dose. How is pt dose lowered by doing this?
It increases the number of X-rays intercepted by it, which means less are going through the pt
Which body type?
Large/heavy
Hypersthenic
Which body type?
High stomach
Hyposthenic
Which body type?
Average athletic build
Sthenic
Which body type?
Transverse stomach
Hypersthenic
Which body type?
Low or medial stomach
Asthenic
Which body type?
High upper left stomach
Sthenic
Which body type?
High lungs
Hypersthenic
MTF is used to denote what?
Overall resolution
What is the hypothetical “perfect” resolution?
when MTF = 1
Fetus dose max for entire pregnancy in mSv and in rem/month (occupational)
Entire pregnancy: 5 mSv
Monthly: 0.05 rem/mo
Occupational exposure limit in rad/min
5 rad/min
More ideal exposure limit per minute/mA with mag at 80 kVp?
2.2 rad/min/mA
Immediate RHB notification required
If total effective dose is…
25 rem +
(0.25 Sv)
Immediate RHB notification required
If eye dose is…
75 rem +
(0.75 Sv)
Immediate RHB notification required
If shallow skin/extremity dose is…
250 rad +
(2.5 Sv)
Conversion factor is a measure of what?
Brightness gain
What is this the equation for?
Intensity of output phosphor
——————————————
Input exposure rate (mrad/sec)
Conversion factor
General public dose limit in mSv/hr
0.02 mSv/hr
General annual public dose limit in mSv
1 mSv
What 4 things influence the level of scatter radiation?
kVp
Area exposed
Thickness
Time exposed
24 hr RHB notification required
If total effective dose is…
5 rem +
(0.05 Sv)
24 hr RHB notification required
If eye dose is…
15 rem +
(0.15 Sv)
24 hr RHB notification required
If shallow dose to skin/extremities is…
50 rem +
(0.50 Sv)
Minification gain is an increase in ___ only.
Brightness
Equation for minification gain
(Input screen diameter) ^2
————————————-
(Output screen diameter) ^2
What is this the equation for?
Focal length in mm
—————————
Diameter in mm
F number
(Lower/higher) F number = more light available
Lower
The F number is basically the relative speed of the _______.
Camera lens
___ graphs the relationship between density and the eradication dose
Characteristic curve
___ is used to correct the resolving power to what actually would be realized in use.
Kell factor
Pixel size equation
FOV
————-
Matrix
Electronic gain happens from the _____.
Minification happens from the _____.
Accelerating anode (which speeds up electrons)
Output image
The output phosphor converts ___ to ___.
Electrons —> light photons
Image intensifier steps to take the inputted X-rays to outputted light photons
- X-rays —> light photons
- Light photons absorbed —> electrons
- Electrons —> accelerated
- Accelerated electrons —> focused
- Focused electrons —> light photons
The ohotocathode absorbs ___ and puts out ___.
Light photons —> electrons
The electrostatic lens focuses what where?
The accelerated electrons onto the output phosphor
Which focal spot?
Manufacturer’s stated anode target size
Nominal
Which focal spot?
X-ray beam length and width
Effective
Which focal spot?
Area of the anode that’s actually struck by the X-ray
Actual
Which focal spot?
Projected focal/anode target size measured at the image receptor
Measured
