A system for treating an ocular tumor having a cone, a collimator, a light source and a camera is disclosed. The cone includes a cone input and a cone output and is capable of being mounted and un-mounted to a treatment nozzle. The cone input receives radiation from the treatment nozzle for the treatment of the ocular tumor. The collimator is coupled to the cone output and configured to collimate radiation received by the cone output. This collimated radiation is directed to the patient having the ocular tumor. The light source coupled to the cone. The light source is configured to provide a focusing point of the eye of the patient. A camera coupled to the cone monitors the position of the eye of the patient.