ABSTRACT
To obtain a more extensive coverage of the patient’s surface, some systems are composed of two or three camera pods. ese ceiling-mounted stereo camera pods work together to build a 3D surface image of the patient. e two pods in the two-pod system or two of the three pods in the three-pod camera system are located laterally to the treatment couch. e other camera in the three-pod camera system is located centrally at the foot of the treatment couch, as shown in Figure 80.2. For some gantry angles, when AlignRT is used for monitoring in real time, the gantry might occlude one of the lateral pods, resulting in coverage of a smaller surface and potentially leading to inaccurate monitoring if only the lateral pods are used. is eect can be more evident when there are couch rotations involved in the treatment. e use of the central pod together with the lateral pods eliminates this problem. For every gantry angle, there are at least two camera pods (central plus one lateral) available for imaging, allowing for accurate monitoring in all situations.
