Dynamic background correction in 3Dt body surface sensing and visualisation

The sensing and visualisation of 3D body surface information is being researched for clinical use in the radiation treatment of cancer, where accurate patient set-up and positional monitoring is essential. Where 3D measurement is based on the projection of structured light onto the patient it is neccessary to remove background detail prior to extracting patient surface topology. Rapid background changes render a single pre-emptive determination of background useless. Instead it becomes necessary to update background information at video-rates. This precludes disruptive pauses for the physical collection of background data. The paper describes a method of generating background data from the video images of the structured light projection itself. Results are presented to show that image frame processing that includes a randomised element of structural spreading is the key to successfully implementing real-time background correction.