Reply To: Vertical shifts from radiographic images

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Marko Laaksomaa
Participant

Forgot to mention one tip if you want to to use this combination of AP+LAT+MV tangential image. You find out that after your possible couch shifts based on AP+LAT image online match, tangential image ribs are not inside your tolerances, for example in VRT/LAT direction. Then you need to write down what is the problem with the tangential image isocenter, go back to match the existing AP+LAT images again to (re)do the couch shifts based on match to the slightly “better” bony structures, which better correlate with the tangential image accuracy and acquire reference surface for the treatment.Then you do not have to re-acquire AP+LAT images or accept tangential image with only moderate accuracy. Then acquire  tangential image once more with the just acquired reference surface. This is what sometimes happens during the first fractions if there is for example pitch in the sternum and thereby uncertainties to select the correct matching location in vertical.