Board Prep- Image Production Flashcards
Image Production
What law does the following pair of exposure factors represent: 100 mA/100ms & 200mA/50ms.
Reciprocity Law
What rule allows you to double or decrease the receptor exposure by half w/o adjusting the mAs?
15%rule
According to inverse square law: as the distance between the x-ray tube & IR increases, the exposure rate ____.
decreases in direct proportion
What happens to scatter radiation when the size of the x-ray field is reduced?
It is also reduced
T or F: X-ray photons can penetrate thru the part, scatter w/in the part, & be absorbed by the part.
True
The number of lead strips per inch in a grid is it’s ____.
Frequency
What can you use to produce the similar effect as using a grid?
Air Gap Technique
Noise (graininess) on a digital image is caused by what?
Underexposure
Automatically program technique (APR) requires the radiographer to select what before imaging a patient?
Anatomic Part
Digital imaging can compensate for approximately __% underexposure & __ % overexposure.
80; 500
What relationship exists between resolution and magnification in imaging?
Inversely
What do you use to rescale pixel values in digital imaging?
Look Up Tables (LUT)
What relationship exists between SID and receptor exposure?
Indirect (as SID increases, receptor exposure decreases)
Where is the mA selector found in the x-ray circuit?
the filament circuit
For digital imaging, the receptor exposure is controlled by adjusting what?
the window level
In fluoro exams, if the tech selects the mag setting, the magnified image is the result of a decrease in the size of what?
the size of the input phosphor
According to the line-focus principle, the effective focal spot is always ___ the actual focal spot.
Smaller than
What effect with increasing the OID have on the spatial resolution of an image?
Decrease spatial resolution
In digital imaging, each pixel represents a 3-D volume of tissue known as a what?
Voxel
If you increase the FSS, how does that affect the spatial resolution of your image?
Decreases spatial resolution
The longer the SID, the ____ the distortion.
less the size of
Using a technique of 400 mA, 0.25s and no grid can be converted to 200 mA at what time with an 8:1 grid?
2s (mAs1/GCF1= mAs2/GCF2)
If the SID is cut in half, what change must occur to the mAs to maintain the exposure?
mAs decreased by 4x
According to the Nyquist frequency, an analog signal must be sampled at what frequency to avoid aliasing or Moire effect on digital images.
2x per cycle
The difference between light & dark areas on a radiography is a definition for what?
contrast
Density was the term to describe overall blackening in film-screen; what term is used in digital imaging to describe this radiographic quality?
Receptor Exposure
What term is used when changing the shape of an object occurs?
Distortion
Size distortion is controlled by what?
Radiographic Distances (SID, OID)
Line pairs per millimeter are used to measure what id digital imaging?
Spatial resolution
What is the best method to reduce scatter radiation, which causes fog?
Collimation
