131 Performance analysis of new Delta4 Phantom+ using Flattening-Filter and Flattening Filter-Free beams. (December 2018)

• Record Type: Journal Article
• Authors: Capomolla, C.; Zagari, A.; Quarta, S.; Luca, D. De; Carlà, A.; Cazzato, M.; Martinucci, E.
• Is Part Of: Physica medica. Volume 56(2018)Supplement 2
• Page Start: 146
• Publication Date: 2018-12
• Subjects: Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2018.04.142
• Languages: English
• ISSNs: 1120-1797

Abstract

Abstract: Purpose: There is a recent increase in the use of Flattening Filter-Free (FFF) beams with the aim of reducing treatment time and consequently intrafractional motions. The goal of this study was to evaluate the performances of the new pre-treatment system Delta 4 Phantom+ (Scandidos) in terms of a stable and sensitive tool for achieving a reliable verification. Methods: Delta 4 + was evaluated for verification with 6 MV and 6 MV FFF beams using static beam arrangement. The accelerator output was monitored with the ionisation chamber inserted into the Phantom. The device was tested for dose-rate dependence, linearity and stability using its daily output correction. The response of Delta 4 + was evaluated for energy, measuring the gamma index of four Volumetric modulated arc therapy (VMAT) plan with different energies (6 MV, 6 FFF MV, 10 MV, 10 FFF MV). Results: The response of Delta4+ as a function of accelerator dose rate is in agreement with the ionisation chamber with a difference smaller than 0, 1%. The Delta4+ output is constant for different MU, being the difference within 0, 4%. The stability was measured during a 6 months period and the standard deviation obtained is 0, 7% for 6 MV and 1% for 6 FFF MV. VMAT plan analysis show values higher of 99% for all energies with a threshold of 3%-3 mm, while with a threshold of 2%-2 mm the values are within 93, 5%-97, 5%. The plans calculated with FFF beams have the lowest value in the range. Conclusions: This study shows that the Delta 4 + is an accurate device, in fact, for all the measurements made, uncertainties below 1% were obtained.