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!!!

PRE-PROCESSING 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

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 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

NYQUIST THEOREM 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.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%

Sample? Try this eRate-c.html eRate-c.html

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

SKIPPING LUT,EXPOSURE LATITUDE, MTF, QC workstation functions FOR NOW….NEXT SEMESTER However let’s discuss image manipulation Window Level Stitching

REVIEW THOSE PESKY ACRONYMS! 1. PSP 2. CRT 3. ADC 4. IP 5. CR 6. DR 7. DQE 8. PMT 9. PACS