M2L2 - Histogram Analysis and EI Errors REAL

EI stand for

exposure index

what happens when EI is at an unacceptable range

histogram analysis error occurs

why are exposure indicatiors not a measurement of patient dose

it does not account for the attenuation of the beam within patient

what system is deviation index apart of, CR or DR

DR

what is target exposure index EI_T

ideal exposure # for each projection

what is signal based exposure index EI_s

the actual image taken and the exposure number of it

what does deciation index calculate for

difference between EIT and EIS

what is a perfect DI on philips

0

DI over 0 means

overexposure

DI under 0 means

underexposure

for CR, what can we do to get a good image

smallest Ir possible, good collimation and centering, erasure of CR PSP

what is histogram analysis error

when LUT does not match and cant be rescaled. the computer cant find good VOI and will present a iamge too dark or bright, not diagnostic

how can histogram analysis happen

• not the proper menu

• incorrect centering and collimation

• external and internal artifacts

why does not selecting the proper menu cause histrogram analysis error

incorrect LUT to compare

why does incorrect centering and collimation

cause histrogram analysis error

poor image histogram and does not match LUT

why does artifacts cause histrogram analysis error

messes up the histogram, may present type III

what is a CR specific histogram analysis error

segmentation or field recogniton, cant read collimation borders on the PSP

what happens when less than 30% of the IR for a CR is not used

turns balck