Role of the Neuroradiologist and Neurosurgeon in Contouring with the Clinical Oncologist for Stereotactic Radiosurgery

Abstract

Aim: To evaluate the value of a multidisciplinary team (MDT), including a neuroradiologist and a neurosurgeon, review of contouring in stereotactic radiosurgery (SRS).

Materials and methods: A sequential audit of all patients receiving intracranial SRS at local institution was conducted. Lesions were contoured first by a clinical oncologist, then reviewed/edited by the MDT. The initial contour was compared with the final contour using Jaccard conformity (JCI) and geographical miss indices (GMI). The dosimetric impact of a contouring change was assessed using plan metrics to both original and final contours.

Results: In total, 113 patients and 142 lesions treated over 22 months were identified. The mean JCI was 0.92 (0.32-1.00) and 38% needed significant editing (JCI <0.95). The mean GMI was 0.03 (0.0-0.65) and 17% showed significant miss (GMI >0.05). Resection cavities showed more changes, with lower JCI and higher GMI (P < 0.05). There was no significant improvement on JCI or GMI shown over time. The dosimetric analysis indicated a strong association of conformity metrics with planning target volume dose metrics; a 0.1 change in gross tumour volume conformity metric association with a 6-17% change in dose to 95% of the resulting planning target volume. Greater association was seen in the resection cavity, suggesting the geographical nature of a typical contouring error gives rise to greater potential change in dose. Clinical outcomes compared well with published series. The median survival was 20 months; the local relapse-free rate in the treated areas was 0.89 (0.8-0.94) at 40 months; the radionecrosis-free rate at 40 months was 0.9 (0.83-0.95) with a median of 17 months to developing radionecrosis.

Conclusions: This work highlights that MDT contour review adds significant value to SRS and the approach translates into reduced local recurrence rates at the local institution compared with previously published data. No improvement in clinical oncologist contouring over time was shown, indicating that a collaborative approach is needed regardless of the experience of the clinical oncologist. MDT input is recommended in particular for contouring of resection cavities.

Keywords: Contour; SRS; multidisciplinary; peer review.