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Impact of camera deviation on curvature assessments using goniometer and 2D photographies

Nascimento , B1; Cerqueira, I2Miranda, E1; Bessa, J1; Fidelis, R1; Guglielmetti, G1; Batagelo, C1; Silva, G1; Nahas, W1; Srougi, M1; Chiesa, G3; Cury, J1

1: Division of Urology, University of Sao Paulo Medical School, Brazil; 2: Engineering - Fundação Educacional Inaciana Padre Sabóia de Medeiros; 3: Engineering - Fundação Educacional Inaciana Padre Sabóia de Medeiros

Objective: Camera deviations during 2D image acquisition might affect CA accuracy. Our aim was to investigate the impact of camera angle deviations on CA results

Method: We performed an experiment in which 2D pictures were taken from 5 models with a known uniplanar curvature (40°, 45°, 60°, 90°, 120°). The model was kept on a fixed point and camera rotated around. Photographies were taken for every 10° increase in camera deviation from the optimal position (perpendicular to curvature plane). Camera rotated to a maximum of 90° deviation in both vertical and horizontal planes. Pictures were analyzed 2 times by 2 different urologists using a standard goniometer. We also calculated for each picture, using trigonometry, the expected apparent curvature (AC) and the corresponding expected picture assessment error (PAE= AC- model curvature). Intra-observer, inter-observer and observer-AC concordance correlation coefficient (CCC) were calculated.

Results: 100 pictures were analyzed. Intra-observer CCC was high (CCC:0.99) for both urologists. Inter observer and observer-AC correlation coefficient were also high (CCC:0.996 and CCC:0.992; respectively). When camera rotated in the horizontal axis, PAE tended to underestimate curvature for models with curvature of less 90°, and to overestimate curvature of the 120° model. When camera rotated in the vertical axis, PAE had an inverse effect. Analyzing its magnitude, irrespectively of model curvature, PAE showed a tendency to increase exponentially with higher deviation, reaching up to 100% for deviation of 80°. Nevertheless, PAE was always <5% for camera deviations of 0-20°

Conclusion: PAE due to non-optimal camera position is a complex phenomenon that differently affects CA depending on the rotation axis and penile curvature degree. Nevertheless, for camera deviations of 0-20°, PAE is always less than 5% and should have minimal impact.


Work supported by industry: no.

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