Image production Flashcards by Emily Montano

Increase mA =

exposure, contrast, spatial, distortion

increase exposure

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Increase kVp =

exposure, contrast, spatial, distortion

increase exposure

decrease contrast

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Increase OID =

exposure, contrast, spatial, distortion

Increase contrast (air gap)
Decrease spatial
Increase distortion

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Increase SID =

exposure, contrast, spatial, distortion

Decrease exposure
Increase spatial
Decrease distortion

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Increase Focal spot size =

exposure, contrast, spatial, distortion

decrease spatial

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Increase grids =

exposure, contrast, spatial, distortion

Decrease exposure

Increase contrast

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Increase flitration =

exposure, contrast, spatial, distortion

Decrease exposure

Increase contrast

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Increase motion =

exposure, contrast, spatial, distortion

Decrease spatial

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Increase anode heel =

exposure, contrast, spatial, distortion

exposure

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pt factors =

exposure, contrast, spatial, distortion

all

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which (SID / OID / SOD) governs sharpness

SOD

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how to get SOD from sid and oid

Sid - oid

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Unsharpness formula w/ and w/o Focal spot

fs x oid/sod OR sod/oid

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Change in SID greater than - should increase tech (mA)

10 %

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Mag formula

SID/SOD

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Anode angle increase =

Larger effective spot

decrease spatial

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Which end is more intense b/c of anode heel

cathode 25% more intense, thicker part goes here

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Spaital resolution 4 variables

motion
SID, OID ,SOD
Focal spot size
size of dels / pixels

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sharpness formula

sod/oid

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Del drop out is b/c of

TFT failure (IR)

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Del saturation

max charge del can hold

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Nyquist theorem

highest spatial resolution that can be recorded

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Nyquist theorem controlled by

pixel pitch

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MTF

modulation transfer function

how well DR can record spatial

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Best way to measure blur in the system

MTF (o=worst)

MTF depends on

del pitch

prenumbra is controlled by

SOD OID focal spot size

Limiting factor for spatial resolution

pixel

Pixel size formula

FOV/matrix

Pixel size decrease = - spatial & - matrix

increase, increase

Pixel pitch

space between pixels

Pixel bit depth

max # of brightness | base of 2

Spatial frequency

min object size

spatial frequency formula

1/2(Psize)

Attenuation coefficient

% of beam absorbed by pt

Attenuation coefficient based on

voxels

Analog to digital converter selects

selects value for dynamic range

DQE

Detective quantum efficiency | converts xrays to signal

- determines overall efficiency of system

DQE

Dels fill factor

% of semiconductor surface area

Indirect CR CCD

scillation lens/fiber optics sensor chip (light into #s)

Indirect DR

``` scintillation cesium iodide gadolinium (xray to light) Photodiode amorphous silicon (light to electrical charge) TFT (collects & processes) ```

DR direct

``` Nonscintillation amphrous silium (xray hits; release electron) TFT (collects & processes) ```

Photostimuable bromides eurpium bromide = light phosphor stores eurpium makes phosphpr release & make electrons

electrical generator

mechnical to electrical

electrical motors

electrical to mechincal

Autotransformer

change voltage to match kvp | selfinduction

step up transformer

volts to kilvolts

rectifier

makes ac to dc

rectifier single-phase ripple

100%

rectifier three-phase ripple 6 pulse

14%

rectifier three-phase ripple 12 pulse

high freq ripple

quantization

values to pixel from grayshade (bit depth)

rescaling

fixes images brightness and contrast

flat field uniformity

evens out brightness from dead pixels

interpolation

fixes dead pixels

histogram analysis

finds useful voi of image

- makes histogram

rescaling

Look up table

makes good level of contrast and broghtness

graduation processing

compares to look up table

grayscale

of value given to pixel

equalization

sharpness, contrast

edgehancement

high pass | improves visibility of small, high contrast areas

smoothing

low pass | reduces noise, spatial and contrast

frequency domain

sorting image from size

halo effect

noise darker gets darker lighter gets lighter

detail processing

see fine details w/o change in contrast

intensity domain

sorting image by values of pixels

window level

brightness

window with

contrast

spatial domain

sorts image by location of pixels

point processing

subtraction

area processing

zooming in and out

global processing

flipping from left to right

DICOM

digital imaging and communication in medicine | protocol for pacs

PACS

picture archiving and communication system | storage, retrieval, manipulation, and transmission of image

RIS

modality work list, radiology data

HIS

stores and manages all systems | assigns medical # and pt info

exposure indicator

amount of light reiceved bt plate

for milli move decimal place over

3 times

for window level and width, increasing =

lower contrast / brightness

15 % rule

increase kvp by 15% doubles exposure

fixed kvp

same kvp | change ma

variable kvp

change kvp same ma | more common

beam intensity formula

intensity1 kvp1^2 / = / intensity2 kvp2^2

base 60

kvp is 2x measured part | 60 + (part x 2)

mA controls

heat that gets to filament

how AEC works

1. chamber gets current 2. capactior holds charge 3. thyratron releases the charge 4. electromagnet switch stope exposure

ACE detectors are placed

in front of the grid

AEC density/intensity control

how sensitive thyraton is

MRT

minimum response time how long circuit takes to pass rad 0.002-.02

inherent filtration

parts of tube | 1.5mm

4cm rule

pt thickness increase by 4cm, double exposure

Minimum change for tech

35% ma | 5% kvp

grid ratio

``` 5:1 2 6 ;1 3 8; 1 4 10;1 5 12;1 5 16;1 6 ```

moire effect

incorrected grid

off level

grid titled, exposure decrease exposure

off focus

sid wrong, decrease density at edges

off center

cr not in center, decrease exopsures

upside down grid

underexposure except in center

how fluoro works

``` image intensifier (xray to light to electrical signal) 1. Input phosphor xray to light 2. photocathode light to electrons 3. electrostatic lens 4. output phosphor electrons to light ```

flux gain

image is brighter b/c of acceleration

minification gain

the output is smaller than the input (brighter image)

total brightness fluoro

flux and minifaction

conversation factor

Ratio of luminance of output vs exposure rate of input

flat panel image intensifier

replaces image intensifer | see better smaller anatomy

grid conversion formula

ma1 grid factor 1 / = / ma2 grid factor 2

DAP

dose area product | total air kerma hit pt

ABC / AERC

kvp and ma adjusted to keep brightness

fluoro sid min

15" | 12" portable

OSLS

Al oxide stimulated by laser to read dose energy released as light

thermoluminescent dosimeter

lithium fluoride crystals

correction factor single phase

correction factor 3 phase & high freq

1.4

output phosphor made of

zinc cadmium sulfide

new ma formula?

direct square law

to find actual image size

image size/mag factor | mag factor = sid/sod (sid - oid)

wide width = - contrast

long, short