3D Body Surface Measurement and Display in Radiotherapy Part II: Dynamic Surface Sensing and Visualisation

Research into large scale, simultaneous measurements across the body surface using spatial phase processing of images of continuously structured light projected on to a patient is described. Data captured at video frame rates provides the very first genuinely dynamic information across the patient body surface during high energy radiation therapy. The chest and pelvis, representing the extremes of such motion, outside of and during irradiation respectively, are considered. The dynamic 3D maps are in the form of 25, 440x440 point surfaces for each second of measurement. The almost continuous spatio-temporal nature of the maps is unique and of high enough resolutions to reveal detailed motion and long sought after deformation patterns. Furthermore, it is shown that display of the dynamic surface data can be reduced to a mean surface height map and a residual surface time series. For both chest and pelvis the residual surface series appear as relatively flat laminae that flex in an unexpectedly simple manner. The display of the residual surface series for the first time directly reveals the scale and distribution of physiological perturbations, including the detection of the periodic effects of respiration in the rear pelvis, remote from the lungs.