Tools needed for Augmented reality Apps
Three physical deviceshave concrete dimensions, are calibrated for related app and are necessary for landmark registration and real time positional guidance.According to app requisitions have to be 3D-printed in Stainless Steel, ULTEM or Peek which can be sterized according to manufacturer own specification and guidelines - STL or OBJ files can be downloaded for free from our web after contact.
a.Case i-Phone -Probe tool (CIPT)
b. Clamp tool (CT)
c. Passive sensor (PS)
-The unsterilized i-Phone should be placed in a sterilized waterproof sealable bag. This is common practice in surgical fields where non sterile parts are usually placed in sterile bags like arthroscopes, cameras, optical wires, tools etc. Sterile bags are readily available in operation rooms, taking always in to account bag manufacturer specification and guidelines. Plastic coverage should be transparent and not blur the iPhone cameras.
-All devices could be sterilised according to manufacture guidelines (CE) for the 3D printed material specification used.
A. A Case i-Phone -Probe tool (CiPT). This device is dedicated for surface registration and the same instrument combined with the next instrument the clamp works as position detector. The tool consist of the case, in which the iPhone sits and the rod. Rod has predefined length ( 32 cm) and it is attached perpendicular to the phones case, at the point where factory defined the centrum of the iPhone. This point is by default the origin in 3D dimensions namely 0,0,0 in XYZ axis.The other side of the rod is the side that acts as pointer tip location (z dimension). In the Case i-Phone -Probe tool (CIPT) the case should be according to the dimensions of iPhone model used. Default values are for Iphone 11 Max Pro
Case i-Phone -Probe tool (CiPT) - a device dedicated for surface registration - should be 3D printed after downloading the appropriate 3D files according to user’s iPhone model from developers site. The device consist of the case, in which the iPhone sits and the rod. Rod has a predefined length ( 32cm) and it is attached perpendicular to the phones case. The other side of the rod is the side that acts as mechanical pointer tip location. The pointer tip sphere in augmented reality (AR) by the app should coincide with the mechanical pointer tip location of the rod in order to measure accurate.
Calibration is achieved by simply pressing the directions buttons (+,-) over the screen, the position (XYZ) of pointer tip sphere in augmented reality (red sphere) is adjusted accordingly. The user aim the pointer tip sphere in AR to be aligned in all dimensions and coincide over the mechanical pointer tip location of the rod of the i-phone in Case.
More specific :
-by pressing the + or - button in the upper row, the (z) distance is adjusted respectively - it is recommended, first to measure manually the distance from tip-pointer to case, by default this is 32 cm, and calibrate first the Z distance - real distance from the case to tip of the pointer. The following x y calibration procedure are in two dimension over the screens phone (x,y), aiming to bring the presented red sphere to coincide optically with actual pointer tip.
-in the intermediate row the + - button adjust the (x) distance of Point tip to red sphere.
-in the last row by pressing the +or - button the (y) distance from the Point tip to red sphere is adjusted likewise.
B. The Clamp tool (CT). This tool is a simple clamp attached to the handle of the inserter or reamer that has a slot designed to receive perpendicular the pointer tip side of the case i-Phone-probe tool (CiPT).
C. Passive sensor (PS). This device is dedicated to act as dynamic reference array during tracking. Once 3D printed and added the adhesive QR-image label over the dedicated surface should be placed in a sterilized waterproof sealable bag and then it should firmly attached to bone or other anatomical landmark by the use of preferably to Swanz screw or a body of mini external fixator.
A built-in known dedicated QR-code Image should be exported from the app and printed in a common colour printer preferably as an adhesive label and attached firmly to passive sensor dedicated surface plane. The dimension of the printed adhesive QR-code Image Label should be four by four in centimetres in order to match perfectly the passive sensor dedicated surface. The printed QR Image is intended to work as unique dedicated tracker and should be in visual proximity. The QR-code Image marker is captured and recognised continuously in real time by the App. Over the printed QR-code Image marker in augmented reality, a red sphere and a green plane appear laying over the surface plane once the QR-code Image is recognised. The QR-code Image marker is constantly recognised and continuously tracked by the app as along as the top centred button is on - highlighted. The Passive Sensor (PS) should be firmly mounted on pelvic bone. The QR-code Image attached over PS acts as a dynamic reference base attached to the system. Prerequisite is visual contact through i-Phones screen of QR-code Image. The position of all future register points are updated continuously while the QR-code Image acts as a dynamic reference guide marker. In case the patient pelvis is placed in different position during surgery and the attached PS on patient pelvis move as a whole array. Accidental change of pelvis position intraopratively is common and the app updates the position of registered points in AR according to the new position of patient pelvis respectively. Aiming the iPhones camera to the PS QR-code image the app recognise the above mentioned image, recalculates the position of the already registered points in AR and updates accordingly their position in the right place over the real patients pelvis in the new position without the need to reregistering the points.