6RECIPROCITY LAWDENSITY ON THE FILM SHOULD BE THE SAME FOR ANY COMBINATION OF mAs as long as the product of the mAs is equal!!!WHAAAAAT????30 mAs300mA x .1 = 30 mAs200 mA x .15 =30 mAs500mA X .06 = 30 mAsSame product
7It makes a difference DIGITAL EXPOSURE ERRORS OF 50% CAN BE ADJUSTED DIGITALLYTHINK ABOUT THAT!
12What do we do in these cases? Casts/splintsBody habitusPathologyIs it always necessary to compensate?NOTE BOX 15-1 ON PAGE 253Soft tissue
13Understanding chest x-ray technical factors Inherently, the composition of the chest is high subject contrast.Black lungs. White bones
14Understanding 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
15CHART DEVELOPMENT-pge 263 in FAUBER Comparative anatomyProportional anatomy
16Abd. 76 kVp, 20 mAs…What do we adjust for the following? Rose AehleA thin but healthy personA Football linebacker or Santa ClausA frail, tiny,elderly person
17IT MAKES A DIFFERENCEmAs change of 30% or higher before a change is notedChanges 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
18TRUE SCENARIO 80 YR OLD WHEELCHAIR BOUND MALE CANNOT GET OUT OF WHEELCHAIRSHOULDER IN NEUTRAL POSITION BUT A FRACTURE IS SUSPECTEDTUBE DOES NOT EXPOSE AT 40”SIDCAN 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.