Epid-based in  vivo dose verification for lung stereotactic treatments delivered with multiple breath-hold segmented volumetric modulated arc therapy.

Epid-based in vivo dose verification for lung stereotactic treatments delivered with multiple breath-hold segmented volumetric modulated arc therapy.
J Appl Clin Med Phys. 2019 Feb 20;:
Authors: Cilla S, Ianiro A, Craus M, Viola P, Deodato F, Macchia G, Buwenge M, Morganti AG, Valentini V, Piermattei A
Abstract
We evaluated an EPID-based in-vivo dosimetry (IVD) method for the dose verification and the treatment reproducibility of lung SBRT-VMAT treatments in clinical routine. Ten patients with lung metastases treated with Elekta VMAT technique were enrolled. All patients were irradiated in five consecutive fractions, with total doses of 50 Gy. Set-up was carried out with the Elekta stereotactic body frame. Eight patients were simulated and treated using the Active Breath Control (ABC) system, a spirometer enabling patients to maintain a breath-hold at a predetermined lung volume. Two patients were simulated and treated in free-breathing using an abdominal compressor. IVD was performed using the SOFTDISO software. IVD tests were evaluated by means of (a) ratio R between daily in-vivo isocenter dose and planned dose and (b) γ-analysis between EPID integral portal images in terms of percentage of points with γ-value smaller than one (γ% ) and mean γ-values (γmean ) using a 3%(global)/3 mm criteria. Alert criteria of ±5% for R ratio, γ%  < 90%, and γmean  > 0.67 were chosen. 50 transit EPID images were acquired. For ...

Source: Journal of Applied Clinical Medical Physics - February 20, 2019 Category: Physics Authors: Cilla S, Ianiro A, Craus M, Viola P, Deodato F, Macchia G, Buwenge M, Morganti AG, Valentini V, Piermattei A Tags: J Appl Clin Med Phys Source Type: research