Dummy run and conformity indices in the ongoing EORTC low-grade glioma trial 22033-26033: First evaluation of quality of radiotherapy planning

Elena Musat*, Erik Roelofs, Raquel Bar-Deroma, Paul Fenton, Akos Gulyban, Laurence Collette, Roger Stupp, Damien C. Weber, J. Bernard Davis, Edwin Aird, Brigitta G. Baumert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Purpose: Early assessment of radiotherapy (RT) quality in the ongoing EORTC trial comparing primary temozolomide versus RT in low-grade gliomas. Materials and methods: RT plans provided for dummy cases were evaluated and compared against expert plans. We analysed: (1) tumour and organs-at-risk delineation, (2) geometric and dosimetric characteristics, (3) planning parameters, compliance with dose prescription and Dmax for OAR (4) indices: RTOG conformity index (CI), coverage factor (CF), tissue protection factor (PF); conformity number (CN = PF× CF); dose homogeneity in PTV (U). Results: Forty-one RT plans were evaluated. Only two (5%) centres were requested to repeat CTV-PTV delineations. Three (7%) plans had a significant under-dosage and dose homogeneity in one deviated > 10%. Dose distribution was good with mean values of 1.5, 1, 0.68, and 0.68 (ideal values = 1) for CI, CF, PF, and CN, respectively. CI and CN strongly correlated with PF and they correlated with PTV. Planning with more beams seems to increase PTVDmin, improving CF. U correlated with PTVDmax. Conclusion: Preliminary results of the dummy run procedure indicate that most centres conformed to protocol requirements. To quantify plan quality we recommend systematic calculation of U and either CI or CN, both of which measure the amount of irradiated normal brain tissue.

Original languageEnglish (US)
Pages (from-to)218-224
Number of pages7
JournalRadiotherapy and Oncology
Volume95
Issue number2
DOIs
StatePublished - May 2010

Keywords

  • Conformal radiotherapy
  • Conformity indices
  • Dummy run
  • Homogeneity
  • Low-grade gliomas
  • Quality assurance

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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