EQUATIONS-UNIT 1-6 Flashcards
How do you calculate the percent varience?
Percent variance: Measured value-set value/set value x 100
How do you calculate the minimum object size?
minimum object size=1/2(1/SF)
How do you calculate causal repeat rate?
Causal repeat rate=#of repeat images /Total # of repeats x100
How do you calculate total repeat rate?
Total repeat rate=Total # of repeat images/toatal # of images taken x 100
How do you calculate pitch?
Pitch=Couch movement per x ray tube revolution (mm)/beam width (mm)
How do you calculate the total amount of anatomy covered?
total amount of anatomy covered=Pitch x acquisition time x beam width/x ray tube rotation time
How do you calculate voxel size/patient thickness?
Voxel size (mm2)=Pixel size (mm2)x slice thickness (mm)
How do you calculate pixel size?
Pixel size=FOV or DFOV/Matrix size
How do you calculate effective mAs?
effective mAs=mAs/pitch
How do you calculate CTDIw
CTDIw=2/3CTDI100(edge) + CTDI 100 (center)
How do you calculate CTDI vol?
CTDI vol=1/Pitch x CTDI w
How do you calculate DLP?
DLP=CTDI (vol) x scan length (cm)
Light field – X-ray field Congruency percentage deviation?
X+X+Y+Y=>2SID
How do you calculate SSDE?
SSDE = CTDIvol x conversion factor (which is based on the patient’s effective diameter).
The effective diameter is defined as the square root of the product of the AP and lateral patient diameters.
