Clinico-Dosimetric Correlation Between Lacrimal Gland Dose and Dry Eyes in Three Dimensional Radiotherapy of Brain Tumors

Background: Brain tumors often require radiotherapy as a key component of treatment. While three-dimensional conformal radiotherapy (3D-CRT) provides better dose distribution compared to conventional techniques, organs at risk (OARs) such as the lacrimal glands may still receive significant radiation exposure. Evaluating the dose–response relationship between lacrimal gland irradiation and subsequent ocular toxicity is therefore essential. So, we aimed to evaluate outcomes of 3D-EBRT in patients with variable brain tumors as regard the severity of dry eye syndrome and to assess the relationship between it and the dose received by the lacrimal gland. Methods: This prospective cohort study was conducted in Clinical Oncology and Nuclear Medicine Department in Zagazig University Hospitals on 24 patients of brain tumors who presented to clinical oncology department to receive either definitive or palliative conformal three dimensional radiotherapy with or without concurrent chemotherapy. Patients were divided into: Group I (Primary group) included 15 patients with primary brain tumors and Group Ⅱ (Metastatic group) included 9 patients with secondary brain metastasis. Delineation of target volume and organs at risk(OAR) was done according to RTOG guidelines. Results: At 6 months, SESoD and TBUT correlated significantly with lacrimal gland dosimetric parameters (Dmax, Dmean, v10Gy, v15Gy, v25Gy). Dryness increased gradually, remaining predominantly minimal or mild. Conclusion: Patients with primary brain tumors, receiving localized radiotherapy, experienced milder ocular side effects, whereas those with metastatic brain tumors, especially after whole-brain radiotherapy (WBRT), showed greater ocular toxicity, including persistent TBUT reduction and increased dryness.