Chapter 7 Carter part one

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Digital Radiographic
Image Processing and
Manipulation
Chapter 7
We’ve learned how images are
captured….now
 What
happens
in the reader
(CR) pre
processing?
 How
is the
image
constructed
digitally?
 LET’S
FIND
OUT!!!

THE READER IS TO
BE INFORMED AS
TO WHAT EXAM
WILL BE
PROCESSED.

PRE-PROCESSING
So when you “flash”
the cassette, or
scan with a bar
code reader or in
DR, choose the
patient and the
examination and
the views that are
to be done
HISTOGRAM
Graphical
representation of
optimal densities
collected by exposure
data recognition .
Exposure data
recognition finds the
collimated edges ,
disregards the scatter
outside of these edges
Searches for anatomy
This area is the source
of exposure data
indicator
CR sampling,
Carter pg 110 and
Page 492 Bushong
Notice the collimated
area of the lungs in A
and find the
associated area in B
on histogram and C
on the response
cure. Do the same
for the black areas
around the chest.
THE SHAPE OF THE HISTOGRAM IS
ANATOMY SPECIFIC
histogram
http://bloggingradiography.blogspot.com/2007/08/anato
my-of-histogram.html
High energy=less frequency of the
same density = narrower histogram
Low energy=more frequencies of
the same density= wider histogram
The Nyquist Theorem
How are signals converted from analog to digital?
THIS IS STILL THE BEST
EXPLANATION AND RESOURCE
When sampling(converting from analog to
digital) a signal, the sampling frequency
must be greater than the bandwidth of
the input signal
 http://images.google.com/imgres?imgurl
=http://www.cs.cf.ac.uk/Dave/Multimedia
/nyquist.gif&imgrefurl=http://www.cs.cf.a
c.uk/Dave/Multimedia/node149.html&h=4
20&w=529&sz=6&hl=en&start=10&um=1
&tbnid=zyDOLJNUH6mM8M:&tbnh=105&t
bnw=132&prev=/images%3Fq%3Dnyquis
t%

NYQUIST THEOREM

http://www.pcguide.com/art/soundSampl
eRate-c.html
Sample? Try this
Automatic rescaling
WHAT DO YOU THINK THIS IS? PAGE
113 CARTER
SKIPPING LUT,EXPOSURE
LATITUDE, MTF, QC workstation
functions FOR NOW….NEXT
SEMESTER

However let’s discuss image manipulation

Window

Level

Stitching
1. PSP
2. CRT
3. ADC
4. IP
5. CR
6. DR
7. DQE
8. PMT
9. PACS
REVIEW THOSE PESKY
ACRONYMS!
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