Page 127 - Demo

Guidesvsaugmentedreality1257Figure23D-printedcranialshapeofatrigonocephalypatientwithsurgicalguide Thegaps(indicatedbyred arrow) wereused to demarcate the VSP on thepatient with apencil Smallrecessesin the guideindicatedananatomicallandmark(bluearrow)tocheckifthesurgicalguidewascorrectlypositionedAUGMENTEDREALITYAPPLICATIONToshowtheVSPinARonthe3D-printedskullsanapplicationwasdevelopedfortheHoloLens(firstversionMicrosoftWashingtonUSA)Unity(v565UnityTechnologies SanFranciscoUSA) and the Vuforia ARUnity 3D toolkit(v71PTCIncMassachusettsUSA) wereused todevelop thisapplicationDifferentphasesof theVSP couldbe visualised on theHoloLens allowing theuser toswitch to the original3DskullmodelseetheosteotomylinesandseeanimatedinstructionshowthebonesegmentsshouldbepositionedTopreventocclusionofthesurgicalviewsolelytheintersectionspointsoftheosteotomiescouldbevisualized(Figure3)PATIENT TRACKINGTodirectlyvisualisetheVSPonthepatientthepositionandorientationofthepatientweretrackedincorrelationwiththeHoloLensTrackingensuredthattheVSPstayedcorrectlypositionedevenwhenthepatientmodelsmovedorwhentheuserreviewedtheplanningfromdifferentanglesForthisa5x5cmstainlesssteelmarkerwithalaser-engravedquickresponse(QR)patternwasattachedtothecalvariamodelsthatcouldbetrackedbythebuilt-incameraoftheHoloLensAstainless-steelpointer,equippedwithasecondQRmarker,wasusedtoindicatefivelandmarksonthe3DmodelWithpoint-basedregistrationtheVSPwasinstantaneouslymatchedtothecranialshapesThedifference(registrationerror)wascalculatedastherootmeansquare(RMS)