Evaluation of Optical Localization in the Visible Band for Ultrasound Guidance in Radiotherapy Using A Robotic Arm

In many medical fields, spatial localization of devices is of paramount importance to e.g. deliver treatments correctly or to perform accurate diagnostic evaluations. Among the different technologies available, optical localization in the visible band of the spectrum offers many advantages: minimum interference with other instruments, flexibility in position of the devices used and extra features such as patient/operator surface tracking or vital signs monitoring. Its application in the domain of radiotherapy is novel, and potentially very beneficial. In this work we introduced a workflow to test the reliability of one of these systems, developed in house, to localize an ultrasound transducer for ultrasound guided radiation therapy (USgRT). Accuracy, precision, latency, sensitive volume and sensitivity to light intensity were evaluated. The workflow we proposed allowed us to establish that, while all the clinically relevant parameters of the system are acceptable, accuracy in locating the transducer could be as poor as 7-8 mm, therefore not acceptable for the intended purpose of the system.