A glance around any operating theatre reveals many visual displays for accessing pre- and intra-operative images, including computer tomography (CT), magnetic resonance imagery (MRI), and fluoroscopy, along with various procedure-specific imaging applications. They support diagnosis and planning and provide a virtual "line of sight" into the body during surgery. Although surgeons rely on the capture, browsing, and manipulation of these images, they are constrained by typical interaction mechanisms (such as keyboard and mouse).
At the heart of the constraints is the need to maintain a strict boundary between what is sterile and what is not. When surgeons are scrubbed and gloved, they cannot touch these input devices without breaking asepsis. To get around it, several strategies are available for interacting with images, though they are often not ideal; for example, surgeons commonly request other members of the surgical team (such as radiographers and nurses) to manipulate images under their instruction.7,11 While it can succeed, it, too, is not without complications. Team members are not always available, producing frustration and delay. Issuing instructions, though fine for relatively discrete and simple image-interaction requests, can be cumbersome and time consuming. More significant, indirect manipulation is not conducive to the more analytic and interpretive tasks performed by surgeons using medical images. The way they interact with, browse, and selectively manipulate them is closely bound up with their clinical knowledge and clinical interpretation.