1. Digital Radiographic Image Processing and Manipulation
Chapter 7

2. We’ve learned how images are captured….now
How is the image constructed digitally?
LET’S FIND OUT!!!
What happens in the reader (CR) pre processing?

3. THE READER IS TO BE INFORMED AS TO WHAT EXAM WILL BE PROCESSED.
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
PRE-PROCESSING

4. 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

5. 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.

6. THE SHAPE OF THE HISTOGRAM IS ANATOMY SPECIFIC

7. histogram

8. High energy=less frequency of the same density = narrower histogram
Low energy=more frequencies of the same density= wider histogram

9. The Nyquist Theorem
How are signals converted from analog to digital?

10. THIS IS STILL THE BEST EXPLANATION AND RESOURCE

11. When sampling(converting from analog to digital) a signal, the sampling frequency must be greater than the bandwidth of the input signal
= /nyquist.gif&imgrefurl= 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

12. http://www.pcguide.com/art/soundSampl eRate-c.html
Sample? Try this

13. WHAT DO YOU THINK THIS IS? PAGE 113 CARTER
Automatic rescaling
WHAT DO YOU THINK THIS IS? PAGE 113 CARTER

14. LUT Automatic rescaling to achieve appropriate contrast on an image

15. LUT –HISTOGRAM OF BRIGHTNESSS LEVELS VALUES FROM IMAGE ACQUISITION
PG 114 IN CARTER
NOTE HOW VALUES LESS THAN 50 ARE BLACK AND THOSE HIGHER THAN 150 ARE WHITE

16. Lut histogram

17. Exposure latitude CCD’s FPIR PSP/CR systems DR (direct or indirect)
High dynamic range of receptors which is the ability of the receptor to respond to exposure
Example of Receptors??
Exposure latitude

18. MTF
The ability to faithfully reproduce the image from the object…More light in the process of capturing image, the lower the MTF. High MTF is preferred

19. Contrast manipulation
Changing brightness, contrast post processing. “No amount of adjustment can take the place of proper technical factor selection”

20. Improving visibility of small high contrast areas (ex: finger fractures)
Usually signals are averaged to shorten processing time and storage
In Edge Enhancement, less pixels are included in the average=more true in signal “size”
Edge Enhancement

21. Smoothing
Reduction of noise and contrast. Good for visualizing fine bone tissues

22. Let’s discuss image manipulation
Window Level
Window Width
Stitching

23. REVIEW THOSE PESKY ACRONYMS!
PSP
CRT
ADC IP CR DR
DQE
PMT
PACS
REVIEW THOSE PESKY ACRONYMS!