Clinical situation and isodose distribution by Ru-106 brachytherapy. (a) Schematic diagram of the corneal zones: applicator zone (A), central zone (B) and distal zone (C), each representing approximately one-third of the corneal vertical diameter. Note that vertical diameter of the cornea is approx. 10.5 mm, and the horizontal diameter 11.5 mm. (b) Photograph of a patient’s eye during brachytherapy: the Ru-106 plaque is located in the upper third of the cornea. (c) Diagram of isodose distribution: Simulation of CCB plaque with a dose of 522 Gy to the tumour base. The directly adjacent cornea receives 2.29 Gy (0.44% isodose), the central zone 0.63 Gy (0.12%) and the distal zone 0.08 Gy (0.015%) over the entire time course of plaque brachytherapy.