Erschienen in:
01.07.2015 | Original Article
A feasibility dosimetric study on prostate cancer
Are we ready for a multicenter clinical trial on SBRT?
verfasst von:
Carmelo Marino, Elena Villaggi, Giulia Maggi, Marco Esposito, Dr. Lidia Strigari, Elisa Bonanno, Giusi R. Borzì, Claudia Carbonini, Rita Consorti, David Fedele, Christian Fiandra, Isidora Ielo, Tiziana Malatesta, Maria Rosa Malisan, Anna Martinotti, Renzo Moretti, Barbara Nardiello, Caterina Oliviero, Stefania Clemente, Pietro Mancosu
Erschienen in:
Strahlentherapie und Onkologie
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Ausgabe 7/2015
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Abstract
Purpose
The Italian Association of Medical Physics (AIFM) started a working group dedicated to stereotactic body radiotherapy (SBRT) treatment. In this work, we performed a multicenter planning study on patients who were candidates for SBRT in the treatment of prostate cancer with the aim of evaluating the dosimetric consistency among the different hospitals.
Methods and materials
Fourteen centers were provided the contours of 5 patients. Plans were performed following the dose prescription and constraints for organs at risk (OARs) of a reference paper. The dose prescription was 35 Gy in five fractions for the planning target volume (PTV). Different techniques were used (3D-CRT, fixed-Field IMRT, VMAT, CyberKnife). Plans were compared in terms of dose–volume histogram (DVH) parameters. Furthermore, the median DVH was calculated and one patient was re-planned.
Results
A total of 70 plans were compared. The maximum dose to the body was 107.9 ± 4.5 % (range 101.5–116.3 %). Dose at 98 % (D98 %) and mean dose to the clinical target volume (CTV) were 102.0 ± 0.9 % (global range 101.1–102.9 %) and 105.1 ± 0.6 % (range 98.6–124.6 %). Similar trends were found for D95 % and mean dose to the PTV. Important differences were found in terms of the homogeneity index. Doses to OARs were heterogeneous. The subgroups with the same treatment planning system showed differences comparable to the differences of the whole group. In the re-optimized plans, DVH differences among institutes were reduced and OAR sparing improved.
Conclusion
Important dosimetric differences with possible clinical implications, in particular related to OARs, were found. Replanning allowed a reduction in the OAR dose and decreased standard deviations. Multicenter clinical trials on SBRT should require a preplanning study to standardize the optimization procedure.