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TECHNIQUE

TECHNIQUE. EVERYTHING YOU WANTED TO KNOW BUT WERE AFRAID TO ASK!!!!. m A s. kVp Body Habitus SID/OID Screen Grids Collimation Thickness of the part Anode heel Reciprocity Law Tube filtration Compensating filters Film Processing Digital Processing.

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TECHNIQUE

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  1. TECHNIQUE EVERYTHING YOU WANTED TO KNOW BUT WERE AFRAID TO ASK!!!!

  2. m A s kVp Body Habitus SID/OID Screen Grids Collimation Thickness of the part Anode heel Reciprocity Law Tube filtration Compensating filters Film Processing Digital Processing Chapter 4 Fauber-Review Density :CONTROLLING FACTORS/INFLUENCING FACTORS: pg 63

  3. k V p Grids Collimation OID Anatomic part Tube filtration Contrast medium Digital imaging Chapter 4 Fauber-Review CONTRAST: controlling/influencing factors pg 63

  4. Contrast and digital imaging • kVp still important but…. • Contrast can be manipulated post processing • Minimizing scatter important since DR is sensitive to scatter

  5. TECHNIQUE REVIEW: SID,OID,COLLIMATION,ANATOMIC PART, ANODE HEEL, GENERATOR OUTPUT,TUBE FILTRATION , COMPENSATING FILTERS FILM PROCESSING

  6. RECIPROCITY LAW • DENSITY ON THE FILM SHOULD BE THE SAME FOR ANY COMBINATION OF mAs as long as the product of the mAs is equal!!! • WHAAAAAT???? • 30 mAs • 300mA x .1 = 30 mAs • 200 mA x .15 =30 mAs • 500mA X .06 = 30 mAs Same product

  7. It makes a difference • DIGITAL • EXPOSURE ERRORS OF 50% CAN BE ADJUSTED DIGITALLY • THINK ABOUT THAT!

  8. LET’S MOVE ON TO BUSHONG NOW CHAPTER 15 PG 244

  9. LET’S REVIEW • TABLE 15-1 – REMEMBER THIS? • WHAT IS A FALLING LOAD GENERATOR? • DIRECT SQUARE LAW? • DOES FOCAL SPOT IMPACT TECHNIQUE? • LET’S MOVE ON TO PATIENT FACTORS, PG 251

  10. Exposure Technique charts What should be on a technique chart? Can the same chart be used for all tubes?

  11. Types of charts – pg 260-265 • Variable kVp, Fixed mAs- • short contrast/more pt exposure • Fixed kVp, Variable mAs • Prefered, longer contrast less patient exposure • High kVp chart • For exams using 100 kVp or higher • Automatic exposure-PATIENT POSITIONING --VERY IMPORTANT • kVp important • OD important • Collimation important • Accessary selection • Anatomically programmed radiography (APR)

  12. What do we do in these cases? • Casts/splints • Body habitus • Pathology • Is it always necessary to compensate? • NOTE BOX 15-1 ON PAGE 253 • Soft tissue

  13. Understanding chest x-ray technical factors • Inherently, the composition of the chest is high subject contrast. • Black lungs. White bones

  14. Understanding chest x-ray technical factors • Therefore to offset the short scale contrast, low mAs is used and high kVp is needed to add the long scale needed to see all anatomy

  15. CHART DEVELOPMENT-pge 263 in FAUBER • Comparative anatomy • Proportional anatomy

  16. Rose Aehle A thin but healthy person A Football linebacker or Santa Claus A frail, tiny,elderly person Abd. 76 kVp, 20 mAs…What do we adjust for the following?

  17. IT MAKES A DIFFERENCE • mAs change of 30% or higher before a change is noted • Changes in kVp in increments of 4 will produce a change in overall density and contrast especially in the lower kVp ranges. • For every one inch of OID, SID needs to be adjusted 7 inches

  18. TRUE SCENARIO • 80 YR OLD WHEELCHAIR BOUND MALE • CANNOT GET OUT OF WHEELCHAIR • SHOULDER IN NEUTRAL POSITION BUT A FRACTURE IS SUSPECTED • TUBE DOES NOT EXPOSE AT 40”SID • CAN EXPOSE AT 72” SID BUT WALL BUCKY DOES NOT MOVE DOWN LOW ENOUGH TO PUT BEHIND THE PATIENT. • WHAT POSITION AND TECHNIQUE SHOULD YOU USE? REFER TO TECHNIQUE CHART FOR THE ROOM THAT WAS A HANDOUT.

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