Optimum radiation technique for retinoblastoma in conserved eyes

The study evaluated 121 consecutive unoperated cases of retinoblastoma in children. They received radiation as the primary treatment for their ocular disease. The stage grouping was done according to Reese classification. Ninety four children had their disease evaluated by CT scan. All except one had imaged lesions in both eyes. In addition, twenty six had thickened optic nerves and twenty one showed chiasmal infiltration. Radiation field selection was based on clinical and CT imaged disease. A tumor dose of 4500c Gy in 16 to 19 fractions over 18 to 24 days was delivered by cobalt teletherapy. The target volume encompassed ora serrata anteriorly and optic chiasma posteriorly in all cases. Tumor response and patient survival was correlated with the initial stage and radiation factors utilised amongst them. Encouraging results were obtained using three field radiation technique with an open anterior field and a TDF between 75 and 90.