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.