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Delivery efficiency and susceptibility to setup uncertainties of flattening filter free lung SBRT: influence of isocentre geometry and treatment mo…

A new interesting article has been published in Phys Med Biol. 2018 Sep 26. doi: 10.1088/1361-6560/aae451. and titled:

Delivery efficiency and susceptibility to setup uncertainties of flattening filter free lung SBRT: influence of isocentre geometry and treatment mo…

Authors of this article are:
Tyler M Dowdell S.

A summary of the article is shown below:
Flattening filter free (FFF) photon beams are frequently used in stereotactic body radiation therapy (SBRT) treatments of lung lesions due to favourable dosimetric characteristics and comparable plan quality to conventional flattened beams. For peripheral targets, the treatment isocentre may remain close to the patient midline to minimise collision risks, which we denote as off-axis geometry (OAG). This study used a cohort of ten patients to investigate the sensitivity of OAG SBRT lung plans to offsets in the isocentre position and compared it to those where the isocentre is placed at the centre of the target volume, i.e. central axis geometry (CAG). Comparisons were made for SBRT treatment plans using 3D conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT). No statistically significant difference was found between OAG and CAG for SBRT treatments delivered with either 3DCRT or VMAT techniques in terms of plan quality metrics. Planned monitor units for 3DCRT plans were significantly less (p<0.001) using CAG compared to OAG for this patient cohort, suggesting more efficient treatment delivery. These significant differences in delivery efficiency based on isocentre geometry were not observed in the VMAT plans. The susceptibility of 3DCRT and VMAT plans to systematic setup uncertainties of 1 mm and 2 mm was not significantly influenced by choice of isocentre geometry. OAG and CAG based treatments are equally robust to systematic uncertainties in isocentre positioning.

Check out the article’s website on Pubmed for more information:



This article is a good source of information and a good way to become familiar with topics such as: Delivery efficiency;Isocentre geometry;SABR;SBRT;Uncertainties;flattening filter free (FFF).

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