Presentation on theme: "TECHNIQUE EVERYTHING YOU WANTED TO KNOW BUT WERE AFRAID TO ASK!!!!"— Presentation transcript:
TECHNIQUE EVERYTHING YOU WANTED TO KNOW BUT WERE AFRAID TO ASK!!!!
Chapter 4 Fauber-Review Density :CONTROLLING FACTORS/INFLUENCING FACTORS : pg 63 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 CONTRAST: controlling/influencing factors pg 63 k V p Grids Collimation OID Anatomic part Tube filtration Contrast medium Digital imaging
Contrast and digital imaging kVp still important but…. Contrast can be manipulated post processing Minimizing scatter important since DR is sensitive to scatter
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
It makes a difference DIGITAL EXPOSURE ERRORS OF 50% CAN BE ADJUSTED DIGITALLY THINK ABOUT THAT!
LETS MOVE ON TO BUSHONG NOW CHAPTER 15 PG 244
LETS REVIEW TABLE 15-1 – REMEMBER THIS? WHAT IS A FALLING LOAD GENERATOR? DIRECT SQUARE LAW? DOES FOCAL SPOT IMPACT TECHNIQUE? LETS MOVE ON TO PATIENT FACTORS, PG 251
Exposure Technique charts What should be on a technique chart? Can the same chart be used for all tubes?
Types of charts – pg 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)
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
Understanding chest x-ray technical factors Inherently, the composition of the chest is high subject contrast. Black lungs. White bones
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
CHART DEVELOPMENT-pge 263 in FAUBER –Comparative anatomy –Proportional anatomy
Abd. 76 kVp, 20 mAs…What do we adjust for the following? Rose Aehle A thin but healthy person A Football linebacker or Santa Claus A frail, tiny,elderly person
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
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 40SID 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.