Table 6 PTV margins for Varian and Elekta linear accelerators that could cover the gross tumor volume with 95% probability at 95% of the institutions, determined assuming that the distance between the imaging and radiation isocenters is zero owing to rigorous QA implementation and that the intra-fraction error caused by treatment couch rotation is zero owing to implementation of a positional monitoring system such as surface image guidance.

From: Spatial accuracy of dose delivery significantly impacts the planning target volume margin in linear accelerator-based intracranial stereotactic radiosurgery

Manufacturer

Direction

Reduced PTV margin size [mm]

Ong

Zhang

Varian

X

1.0

1.5

Y

1.0

1.1

Z

1.0

2.0

Elekta

X

1.5

1.9

Y

1.5

1.6

Z

1.5

2.3

  1. The margins in three directions are shown, and they were derived from 3D-SS analysis of the dose delivery accuracy and the residual setup errors reported by Ong et al.26 and Zhang et al.20.
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