Comparison of Hippocampal Sparing Intensity Modulated Radiotherapy Plans in Patients of Brain Tumors treated by Three-dimensional Conformal Radiotherapy

Introduction: Radiotherapy plays a key role in brain tumorsafter surgery. However, concerns regarding neurocognitivetoxicity after radiotherapy are being raised. Newer radiotherapytechniques can deliver radiotherapy with better precisionplanning and delivery. Effective hippocampal sparing is possiblewith IMRT which governs the neurocognitive functions. Thepresent study is done to compare whether hippocampal sparingis possible in brain tumors by 3D Conformal Radiotherapyand Intensity Modulated Radiotherapy and their effects onneurocognitive functions.Materials and Methods: Twenty-two patients with brain cancerwere recruited from November 2019 to April 2021. Patients weretreated with 3D-CRT technique and alternate IMRT plans weregenerated. Dosimetric parameters of PTV, organs at risk alongwith hippocampus were evaluated and compared for 3DCRTand IMRT plans. Neurocognitive functions were evaluatedusing MMSE score.Result: In study group, there were 16 males and 6 females withmedian age 45 years. Brain tumors were commonly located infrontal lobe (36%) followed by parieto-occipital lobe (18%) andfronto-temporo-parietal lobe (13.63%). PTV parameters werebetter for IMRT and statistically significant. The OARs did notshow significant difference except in both lens though they arewithin tolerance limits. There is no significant difference in thedosimetric parameters of hippocampus in 3D-CRT and IMRTplans. The p-value for Dmax is 0.79, Dmean is 0.26, Dmin is0.18 between hippocampal sparing radiotherapy plans.Conclusion: Anatomic location of tumor plays a key role indeciding hippocampal sparing. Patients whose NCFs showedimprovement on subsequent visits, highlights the fact thatprimary tumor control is a key factor in deciding decline orimprovement in NCFs. It should be beneficial for LGG that havebetter survival and prognosis as compared to HGG cases.