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Dose reporting mode affected spine SBRT audit results

A national end-to-end audit found acceptable spine stereotactic radiotherapy accuracy but systematic differences between dose-reporting conventions.

RadOncToday · ·1 min read

KEY POINTS

  • The audit analysed 59 plans from 44 treatment-planning systems across 41 centres, using anthropomorphic phantoms, alanine detectors and radiochromic film.
  • Plans prescribed 27 Gy in three fractions and were produced using local clinical planning and image-guidance protocols.
  • Mean target-dose differences were 1.2% with alanine and 1.0% within the 100% film isodose, although individual differences ranged to approximately ±8.5%.
  • Dose-reporting mode - dose to water in water, dose to water in medium or dose to medium in medium - significantly affected alanine and film dose comparisons.
  • Geometric agreement remained strong: mean distance to agreement was 0.82 mm, and mean centre-of-dose difference was 0.78 mm, without a significant reporting-mode effect.

CLINICAL TAKEAWAY

Most participating centres delivered spine stereotactic radiotherapy with acceptable dosimetric and geometric accuracy. Audit interpretation must nevertheless account for the treatment-planning system’s dose-reporting convention, particularly when measurements are performed in vertebral bone-equivalent material.

SOURCE

Physics and Imaging in Radiation Oncology