141. A preliminary study to evaluate the impact of calculation grid resolution and CT slice thickness on TPS calculated small fields OF

Autor: R. Consorti, Stefano Agostinelli, Antonella Soriani, P. Bagalà, E. Menghi, Carmelo Marino, E. Moretti, T. Malatesta, G.R. Borzì, S. Russo, Giacomo Reggiori, F. Romagnoli, S. Linsalata, G. Benecchi, C. Iervolino, Marco Esposito, C. Carbonini, Stefania Clemente, Sara Broggi, Marco Fusella, Christian Fiandra, Anna Delana, Marta Casati, Maria Daniela Falco, L. Manco, M. Casale, D. Corletto, B. Nardiello, P. Mancosu, Sara Bresciani, Cristina Garibaldi, E. Villaggi
Rok vydání: 2018
Předmět:
Zdroj: Physica Medica. 56:151-152
ISSN: 1120-1797
DOI: 10.1016/j.ejmp.2018.04.152
Popis: Purpose Stereotactic Body Radiation Therapy (SBRT) for patients with early stage solid tumor is increasing thanks to modern technologies and integrated image-guided systems. A national study to evaluate the influence of calculation grid resolution and CT slice thickness on small fields calculated in an homogeneous phantom, is in progress. For this purpose, a preliminary investigation that collected different parameters on TPS management at Italian level, was performed. Methods Twenty-eight centres of the Italian Association of Medical Physics (AIFM) SBRT working group were invited to fill out a questionnaire expressly prepared by expert Medical Physicists using Google Forms. Questions regarded: type of accelerator, MLC characteristics, CT images scan information, Treatment Planning System (TPS) type, strategy used for SBRT plans, small fields OF values, detector/detectors and set-up adopted for measurements. Results Preliminary results from 28 centers show great heterogeneities. Most centers used LINACs with MLC width ⩽5 mm, 6MV and VMAT technique. 60% of centers used more than one detector to measure OFs and no corrective factor was adopted in small field data. 10 × 10 cm2 field size was the normalization field. OF data inserted in TPS did not come from a multicenter OF measurements. 1 × 1 cm2 was the smallest field size measured for 47% of centers. As for TPS, PB, CCC, MC, AAA and deteministic algorithms were used in 3%, 40%, 23%, 27% and 7% of centers, respectively. About 29% and 21 % of centers used 3 mm and 2 mm as CT slice thickness, respectively. 50% of centers used 2 mm calculation grid. Conclusions The influence of the dose calculation resolution and CT slice thickness on small OFs has not been studied yet. This preliminary study, considered as the starting point, highlighted a great spread of answers of the participating center and could be used as a baseline for future investigations.
Databáze: OpenAIRE
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