Serenella Russo1, Giacomo Reggiori2, Elisabetta Cagni3, Stefania Clemente4, Marco Esposito5, Maria Daniela Falco6, Christian Fiandra7, Francesca Romana Giglioli8, Marco Marinelli9, Carmelo Marino10, Laura Masi11, Maria Pimpinella12, Michele Stasi13, Lidia Strigari14, Cinzia Talamonti15, Elena Villaggi16, Pietro Mancosu2. 1. Medical Physics Unit, Azienda USL Toscana Centro, Firenze, I-50012 Firenze, Italy. Electronic address: serenella.russo@uslcentro.toscana.it. 2. Medical Physics Unit of Radiation Oncology Dept., Humanitas Research Hospital, Milano, Italy. 3. IRCCS - Arcispedale Santa Maria Nuova, Reggio Emilia, Italy. 4. A.O.U. Federico II, Napoli, Italy. 5. Medical Physics Unit, Azienda USL Toscana Centro, Firenze, I-50012 Firenze, Italy. 6. SS. Annunziata Hospital, Chieti, Italy. 7. Dep. of Oncology, Radiation Oncology Unit, University of Torino, Italy. 8. A.O.U. Città della Salute e della Scienza di Torino, Torino, Italy. 9. INFN - Dipartimento di Ingegneria Industriale, Università di Roma 'Tor Vergata', Roma, Italy. 10. Humanitas C.C.O., Catania, Italy. 11. Department of Medical Physics and Radiation Oncology, IFCA, I-50139 Firenze, Italy. 12. Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA-INMRI C R Casaccia, Roma, Italy. 13. A.O. Ordine Mauriziano di Torino, Torino, Italy. 14. Laboratory of Medical Physics and Expert Systems, Regina Elena Cancer Center IFO, Roma, Italy. 15. Università degli Studi di Firenze, A.O.U. Careggi-Medical Physics Unit, Firenze, Italy. 16. AUSL Piacenza, Italy.
Abstract
PURPOSE: The aim of the study was a multicenter evaluation of MLC&jaws-defined small field output factors (OF) for different linear accelerator manufacturers and for different beam energies using the latest synthetic single crystal diamond detector commercially available. The feasibility of providing an experimental OF data set, useful for on-site measurements validation, was also evaluated. METHODS: This work was performed in the framework of the Italian Association of Medical Physics (AIFM) SBRT working group. The project was subdivided in two phases: in the first phase each center measured OFs using their own routine detector for nominal field sizes ranging from 10×10cm2 to 0.6×0.6cm2. In the second phase, the measurements were repeated in all centers using the PTW 60019 microDiamond detector. RESULTS: The project enrolled 30 Italian centers. Micro-ion chambers and silicon diodes were used for OF measurements in 24 and 6 centers respectively. Gafchromic films and TLDs were used for very small field OFs in 3 and 1 centers. Regarding the measurements performed with the user's detectors, OF standard deviations (SD) for field sizes down to 2×2cm2 were in all cases <2.7%. In the second phase, a reduction of around 50% of the SD was obtained using the microDiamond detector. CONCLUSIONS: The measured values presented in this multicenter study provide a consistent dataset for OFs that could be a useful tool for improving dosimetric procedures in centers. The microDiamond data present a small variation among the centers confirming that this detector can contribute to improve overall accuracy in radiotherapy.
PURPOSE: The aim of the study was a multicenter evaluation of MLC&jaws-defined small field output factors (OF) for different linear accelerator manufacturers and for different beam energies using the latest synthetic single crystal diamond detector commercially available. The feasibility of providing an experimental OF data set, useful for on-site measurements validation, was also evaluated. METHODS: This work was performed in the framework of the Italian Association of Medical Physics (AIFM) SBRT working group. The project was subdivided in two phases: in the first phase each center measured OFs using their own routine detector for nominal field sizes ranging from 10×10cm2 to 0.6×0.6cm2. In the second phase, the measurements were repeated in all centers using the PTW 60019 microDiamond detector. RESULTS: The project enrolled 30 Italian centers. Micro-ion chambers and silicon diodes were used for OF measurements in 24 and 6 centers respectively. Gafchromic films and TLDs were used for very small field OFs in 3 and 1 centers. Regarding the measurements performed with the user's detectors, OF standard deviations (SD) for field sizes down to 2×2cm2 were in all cases <2.7%. In the second phase, a reduction of around 50% of the SD was obtained using the microDiamond detector. CONCLUSIONS: The measured values presented in this multicenter study provide a consistent dataset for OFs that could be a useful tool for improving dosimetric procedures in centers. The microDiamond data present a small variation among the centers confirming that this detector can contribute to improve overall accuracy in radiotherapy.