PBT planning
Planning process consisted of target, organ at risk delineation, treatment prescription with required dose volume constraints and treatment optimization to achieve desired dose constraints. Suitable plans were generated either with single-field or multi-field optimization technique (SFO or MFO) or a combination of both (referred to as Hybrid plans) which were robust to range and setup uncertainties up to acceptable thresholds. A pre-treatment patient specific quality assurance (PSQA) was carried out to verify the approved plan before the treatment was implemented. Each day pre-treatment imaging with KV-X rays and/or CBCT was carried out to verify the patient position and to ensure the precision of treatment on a daily basis. Patients were followed up atleast weekly to assess the treatment toxicities (NCI CTC version 4.0). Repeat check scans(CT or MRI) weredone periodically (once in 1-2 weeks as decided by the treating team) orif required during the treatment (on the basis of clinical or CBCT information). Patients received concurrent chemotherapy as per the treatment plan. All patients underwent response assessment imaging 4-12 weeks following treatment and were followed up regularly.Data was analysed using SPSS version 22. Relevant treatment and tumor related factors and their association with acute toxicities wereanalysed using Chi-square test and multivariate analysis of variance. When multiple clinical target volumes (CTV) were irradiated to different doses, CTV that was prescribed a lower dose was considered for analysis.