Results
47 patients with a median age of 9 years (2-25 years)were treated at our institution with image guided PBS PBT till the cut-off period. During this period this patient population constituted 28% of the total patients treated with PBT at our centre. Table-1 describes the baseline characteristics of the patients. 27 patients were diagnosed with a CNS tumor, and the rest with a non-CNS tumor [Fig-1a and 1b].The most common diagnosis was ependymoma followed by rhabdomyosarcoma (RMS) and glioma. 23 patients who had recurrent disease were referred for PBT of which 7 patientswere for re-irradiation.13 children (80% of children younger than 6 years and 2 children between 6-8 years) required atleast one procedure of sedation during either simulation and/or treatment[Fig 2a and 2b]. Of these, only 7 required sedation during the entire treatment (all of them were <4 years except one autistic child who was 8 years old).
Treatment related characteristics have been described in Table-2. Among patients who received CSI, 3 patients were younger than 6 years, 7 were between 7-15 years and 3 were >15 years. One 15-year-old girl with an intracranial germinoma received whole ventricular irradiation (WVI).On analysis of the technique of PBT planning, MFO was used in 21 patients (of which 17 were non-CNS tumors), SFO was used in 11 patients (all of them being CNS tumors) and hybrid planswere used in 15 patients (including all 13 patients of CSI). Median number of fractions received was 30 (23-33) for CNS patients to a median dose of 54CGE(40-55.8Gy) and 32 (17-35) for non-CNS patients to a median dose of 59.4CGE (30.6-70.4). One patient of recurrent para-meningeal RMS received hyperfractionation with 52.8CGE in 40 fractions with a twice daily fractionation.
Median number of CBCT’s per patient for CNS tumors was 16 (4-29), whereas for patients with non-CNS tumors it was 20 (7-33). 6 patients underwent an adaptive re-planning based on the check CT scans and/or CBCT imaging. 16 patients (34%) also received concurrent chemotherapy as per the original treatment plan.