The accuracy of length and angle measurement in videoconferencing teleradiology

Telemedicine was used to make measurements on a series of radiographs. The first group consisted of 25 radiographs of the cervical spine; four lengths were measured on each. The second group consisted of 100 wrist radiographs showing Colles fractures; the degree of backward angulation of the distal fragment was measured on each. Measurements were made via a videoconferencing link. The consultant used the shared white boarding facility to indicate where on the film the measurements were to be made. The videoconferencing link was used to check that the measurements were being made correctly and a nurse measured lengths and angles. In addition, the consultant used the link to read the scales on the measuring instruments for himself. Four different methods of measuring length were tested and three methods of measuring angle. A transparent plastic ruler was best for measuring length-the emergency nurse practitioner and the consultant made almost all measurements to an accuracy of 1 mm. A protractor with pen marker was best for measuring angles; all were made to within 2 degrees. Simple methods can be used to measure lengths and angles in videoconferencing teleradiology.