3D dose delivery QA using couch and gantry mounted cameras

While 2D planar radiation therapy quality assurance techniques suffice for linac verification, a full 3D dosimetry measurement is ideal for robust treatment plan verification. In this study, an optical 3D dose reconstruction technique based on radioluminescence imaging is presented, using two orthogonal views provided by gantry and couch mounted cameras. Both small field and multi-target beam apertures were tested, mimicking typical 3D radiosurgery plans. Pass rates >94% for 3D gamma with 2%/2mm were achieved in all cases. Slice images were used for gamma analysis in each of transverse, sagittal and coronal planes, through the point of maximum dose. This proposed system can enable real-time imaging of beam delivery dynamics in a cylindrical water-equivalent phantom with high spatial resolution 3D reconstruction of the dose distribution, and verification of each beamlet used.