A real time cost effective geometry calibration method for isocenter tracking of a rotating gantry using optical vision sensors

In this paper, a real time and cost effective deformation sensor system is proposed to verify isocenter sphere of a dual-head radiation imaging device within its driving range. For the effectiveness in sensing, installation point was decided according to the finite element deformation analysis of the device model. The proposed sensor was implemented to the device, and then the result was evaluated by comparison with an optical tracker position data. In this method, attachable optical system were designed and implemented to the dedicated radiography system. From the attachment test relative deformation data of two orthogonal X-Ray tube and detector sets were obtained simultaneously by two image sensors attached on each of them. Laser spot orbits were obtained as a result, and were compared with optical tracker data results for verification. The proposed method significantly reduces costs and time spent for calibration process while satisfying micro scale precision requirements and it is applicable to other rotation mechanical system. Comprising devices costs much less than the manufacturing or purchasing a dedicated geometry phantoms, because this method only requires a low powered spot laser and a CMOS Camera plus additional optical devices.