A Smart-Phone App for Actual (Not Relative) Length, Girth and Angle Measurements of the Erect Penis by Patients and Surgeons
Maurice M. Garcia, M.D., MAS. Department of Urology, University of California San Francisco
Introduction and Objective: It is often desirable to measure the actual length, width, or curvature of an object such as the erect penis. However, owing to the difficulty with achieving natural erection in a clinic setting, this is not feasible. Instead, we depend on photographic images captured by the patient. Photographic images are distorted by both lens angle and distance from the camera. A simple yet accurate means of measurement would facilitate pre-op counseling, and document pre-op length and angle, both for research and medico-legal purposes.
Materials and Methods: We describe an App (MedMeasure!; Apple iTunes) that allows one to measure actual length, using either a live smartphone image or from an archived 2-D image. The App eliminates angle distortion by guiding the user to position the camera to yield a true anterior/posterior view. The User selects a reference object (RO) and places this beside the target. A novel RO may be used, or, one can be selected from a menu of objects of known diameter. A virtual caliper device is superimposed on a target and manipulated by the user, to measure the on-screen length of the target. The caliper is calibrated to the RO, and thereafter, the caliper measures the length of any object in the same plane as the RO in real dimensions. A working prototype of the App was programmed and used to calculate the actual length, width, and curvature of various targets (whose actual length/curvature is known). Measurements were repeated 6X, by 6 non-surgeons. Measurements were also made from archived 2-D images (i.e. post-hoc), with equal precision and accuracy.
Results: Actual length and width were compared to measured length/area. Accuracy and precision were calculated. Provided that the target occupies at least 30% of the image field of view, accuracy was >98%, regardless of units or magnification. Precision was 95-99%.
Conclusion: Used on a smartphone, the described App serves important mobile-health needs: a means by which patients can record both body appearance and actual-size measurements in a natural setting. This App can be useful to guide pre-op planning and counseling, and to document pre-op measurements.
Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute Of Child Health & Human Development of the National Institutes of Health under Award Number K08HD069462. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.