Abstract
BACKGROUND: There have been numerous reports of impairment in neurocognitive functions, including visual processing speed (VPS), among patients who have developed brain metastasis. Therefore, this study aims to develop a model that calculates the probability of normal tissue complication arising from VPS impairment after whole-brain radiotherapy. MATERIALS AND METHODS: In this study, 18 patients were examined for VPS impairment at the 4-month follow-up. After the hippocampus delineation, dose-volume histograms (DVHs) were generated. Normal tissue complication probability (NTCP) models were calculated for VPS using the Lyman model and multivariable logistic regression analysis. RESULTS: VPS was observed in 33.3% of patients. TD(50) was obtained at 38.43 Gy. The most predictive variable in univariate analysis was V(Tot), but none of the dosimetric and clinical variables were selected as predictive variables in the multivariate regression analysis (P > 0.05). The overall predictive performance of both models was satisfactory; however, multivariate logistic regression was superior. CONCLUSION: This study modeled the probability of VPS following irradiation of the hippocampus. The NTCP curve showed that by keeping a maximum dose of hippocampi less than 20 Gy, NTCP becomes <25%.