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

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

doi:10.1016/j.radonc.2010.03.005

« Previous Next »Radiotherapy & Oncology
Volume 95, Issue 2 , Pages 218-224, May 2010

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

Elena Musat
- Radiation-Oncology Department, Institute Curie – René Huguenin Hospital, Saint-Cloud, France
- EORTC Headquarters, Brussels, Belgium
- Corresponding author at: Radiation-Oncology Department, Institute Curie – René Huguenin Hospital, 35 Rue Dailly, 92210 Saint-Cloud, France.
Erik Roelofs
- Radiation-Oncology Department, Maastricht University Medical Centre (MUMC), The Netherlands
Raquel Bar-Deroma
- Oncology Department, Rambam Medical Center, Haifa, Israel
Paul Fenton
- EORTC Headquarters, Brussels, Belgium
Akos Gulyban
- EORTC Headquarters, Brussels, Belgium
Laurence Collette
- EORTC Headquarters, Brussels, Belgium
Roger Stupp
- Centre Hospitalier Universitaire Vaudois, University of Lausanne, Switzerland
Damien C. Weber
- Radiation Oncology Department, Geneva University Hospital, Switzerland
J. Bernard Davis
- Radiation Oncology Clinic and Policlinic, University Hospital, Zurich, Switzerland
- Deceased 2008.
Edwin Aird
- Medical Physics Department, Mount Vernon Hospital, Northwood, Middlesex, UK
Brigitta G. Baumert
- Radiation-Oncology Department, Maastricht University Medical Centre (MUMC), The Netherlands

Received 19 May 2009; received in revised form 18 February 2010; accepted 6 March 2010. published online 09 April 2010.

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 PTV_Dmin, improving CF. U correlated with PTV_Dmax.

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.

Keywords: Conformal radiotherapy, Dummy run, Conformity indices, Low-grade gliomas, Homogeneity, Quality assurance