Depth separation in ten observers with a new stereoscopic X-ray acquisition system.

The aim of this work was to assess the depth separation of a new X-ray digital stereo angiographic system through visualization on a stereoscopic monitor. Before starting the clinical trial of this new stereo-digital angiographic system, it seemed to us mandatory to assess the inherent performance of the system to depict depth information, as well as the ability of the users to work with it. With this idea we designed a global test based on the observation of a physical test object by the potential users of the system, during a session long enough to simulate an angiographic study. The acquisition system consisted of a twin focal-spot X-ray tube and a standard DSA DG 300 (General Electric/CGR). The stereo display was controlled by a liquid crystal modulator placed in front of a black-and-white monitor. Special polarized glasses worn by the observers allowed right- and left-image separation. Depth separation was measured in ten observers by means of a stereoscopic test object. Six of the ten observers were able to locate accurately three-dimensional patterns separated by a 12- to 1.5-mm gap. No learning effect was noticed. This result suggested that stereo display through wireless polarized glasses coupled to up-to-date digital subtraction angiography technology may provide an accurate and ergonomic way to a dimensional enhancement of X-ray angiography.