Comparison of dosimetric parameters for predicting radiation-induced cataract in paediatric patients

Introduction

This study compared the predictive ability of radiation-induced cataract between maximum point dose of the lens (Lens Dmax) ≥7 Gy, mean lens dose (Lens Dmean) ≥7 Gy, Lens Dmax ≥10 Gy, and Lens Dmean ≥10 Gy.

Methods

Patients aged 3–18 years received cranial irradiation or radiation therapy at head and neck area between January 2010 and December 2019 at our institute were included. Patients without baseline and/or follow-up eye examination were excluded. Receiver operating characteristic (ROC) curves identified potential predictors and Cox regression analysed correlations between potential factors and cataract occurrence.

Results

Sixty-three patients (122 eyes) were analysed. Cataracts were detected in 14 eyes (11.5%). Median follow-up time was 4 years (range 0.5–10 years), with cataract developing in a median of 2.5 years (range 0.3–7 years). Three patients (21.4%) developed grade ≥3 cataract. Lens Dmean ≥10 Gy was associated with cataract formation.

Conclusion

Lens Dmean ≥10 Gy showed the highest ability for predicting radiation-induced cataract in paediatric patients. Net reclassification improvement (NRI) suggested that changing lens dose constraint from Dmax <7 Gy to Dmean <10 Gy would miss 7% of cataract cases but avoid 28% of unnecessary restrictions. Adopting a mean lens dose <10 Gy was suggested as a constraint for lens dose.