Exposure Indicators

S or Sensitivity number is the amount of luminescence emitted at

1 mR at 80 kvp and value of 200

Typical values range from

1.6 to 2.3

(S# range) GI

100-300

(S# range) Abdoment

100-400

(S# range) Chest, port

100-400

(S# range) skull

100-400

(S# range) spine

100-400

A IgM of 2.9 equals twice the exposure of

2.6 IgM and an IgM of 2.3 equals half that 2.6 ( direct relationship)

A 1 mR exposure at 80 kVp combined with aluminum/ copper filtration yields an EI number of

200

(S# range) Chest, General

200-600

(S# range) Chest pedi

200-700

Abdomen, Pedi

200-700

Kodak CR image -EI =

2360

(S# range) Extremities

75-200

Carestream Kodak

El

Sensitivity is how fast the plate will make the

Image look dignostic

Agfa

LgM

For fuji, Philps and Konica systems the exposure indicator is known as the

S or Sensitivity number

In the direct relationship of exposure and EI each change of 300 results in change in exposure by

a factor of 2

As a starting point, Kodak recommends using CR as a 200-speed system for________________

chest and General Radiography and 100 speed system for Extremity radiography

An exposure of 20 uGy at 75 kVp with

copper filtration yields a IgM of 2.6

L Value- latitude represents the number of

decades covered by exposure

Why does the dependences for CR systems differ from those observed for screen-film systems because of

differences in the composition of the screens

Use of speed is inappropriate to describe

digital systems

Over exposure is

dose creep

An EI plus 300 (EI + 300 ) is equal to a ____________________, and an EI number of - 300 is equal to

doubling of exposure, Halving the exposure

Each step of 0.3 above or below 2.6

equals an exposure factor of 2

The exposure needed to obtain satisfactory images with Kodak CR systems depends on the type of

examination and the radiologist's ppreferences

With a kodak CR systems appropriate exposures for each examination type must be determined based on regulatory

exposure guidelines and acceptable image noise levels

low screen speed system

for extremity

Exposure index refers to the amount of exposures received by

image receptor, not the patient ( manufacturers differ)

The inverse relationship of exposure and the S number amounts to exposure change of 200 results

in a change in exposure by a factor of 2

The amount of exposure and S number is an

inverse relationship

The relationship between exposure and exposure index depends on

kVp` Beam filtration the amount of scattered radiation objects exposed " metal implants patients anatomy" manufacturer technique directly or indirectly proportional to radiation striking IR

low speed =

low contrast

Agfa systems use the logarithm of the

median exposure (IgM) middle

The base exposure indicator number for all systems designates the ___________________________. The ranges depend on proper__________________.

middle of the detector operating range calibration of equipment

On one layer screen lower speed better detail but

more mAs is needed

For Kodak, changes in exposure obtained by changes in mAs will generally affects the

noise of the resulting image

high speed =

noisy

Exposure numbers outside the range indicate

overexposures and underexposure (pediatric exam ranges vary)

The amount of light given off by the imaging plate is a result of the

radiation exposure that the plate has received.

Exposure indicators represent the minimum and maximum exposure numbers that correspond with

radiation exposures within the diagnostic range

Fuji

s -number

System can operate at any_____________ but it doesn't mean

speed image is ideal

Direct relationship ; the higher the EI

the higher the exposure

The higher (S) Sensitivity number

the lower the exposure

Each exposure menu has a range that sets

the minimum and maximum l value

Why is the light converted into a signal

to calculate the exposure index number

filters are made of

tungston

If S# 400 is half the exposure of an S number of 200 and therefore 100 is

twice the exposure of 200

This is based on logarithms, only instead of

using 0.3 as change by a factor of 2 the larger number 300 is used.

Better hot than not, taking out the black bring image back by

window width and window leveling