Dummy run and conformity indices in the ongoing EORTC low-grade glioma trial 22033-26033: First evaluation of quality of radiotherapy planning.
OBJECTIVE
Early assessment of radiotherapy (RT) quality in the ongoing EORTC trial comparing primary temozolomide versus RT in low-grade gliomas.


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 x 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).


CONCLUSIONS
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.
Musat
Elena
E
Radiation-Oncology Department, Institute Curie - René Huguenin Hospital, Saint-Cloud, France. musat@crh1.org
Roelofs
Erik
E
Bar-Deroma
Raquel
R
Fenton
Paul
P
Gulyban
Akos
A
Collette
Laurence
L
Stupp
Roger
R
Weber
Damien C
DC
Bernard Davis
J
J
Aird
Edwin
E
Baumert
Brigitta G
BG
D000328:Adult; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D016543:Central Nervous System Neoplasms / Q000532:radiotherapy*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D005910:Glioma / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal; D000077204:Temozolomide; D016896:Treatment Outcome
D018906:Antineoplastic Agents, Alkylating; D003606:Dacarbazine; D000077204:Temozolomide