Highlights
- •This is the first multicenter study of secondary plan checks for non-C-arm linacs.
- •A total of 973 CyberKnife, Vero4DRT, and TomoTherapy treatment plans were assessed.
- •A 5% difference in the check is feasible as an action level for non-C-arm linacs.
- •A 3–4% systematic difference in the check is apparent in heterogeneous conditions.
Abstract
Purpose
This report covers the first multi-institutional study of independent monitor unit
(MU)/dose calculation verification for the CyberKnife, Vero4DRT, and TomoTherapy radiotherapy
delivery systems.
Methods
A total of 973 clinical treatment plans were collected from 12 institutions. Commercial
software employing the Clarkson algorithm was used for verification after a measurement
validation study, and the doses from the treatment planning systems (TPSs) and verification
programs were compared on the basis of the mean value ± two standard deviations. The
impact of heterogeneous conditions was assessed in two types of sites: non-lung and
lung.
Results
The dose difference for all locations was 0.5 ± 7.2%. There was a statistically significant
difference (P < 0.01) in dose difference between non-lung (−0.3 ± 4.4%) and lung sites
(3.5 ± 6.7%). Inter-institutional comparisons showed that various systematic differences
were associated with the proportion of different treatment sites and heterogeneity
correction.
Conclusions
This multi-institutional comparison should help to determine the departmental action
levels for CyberKnife, Vero4DRT, and TomoTherapy, as patient populations and treatment
sites may vary between the modalities. An action level of ±5% could be considered
for intensity-modulated radiation therapy (IMRT), non-IMRT, and volumetric modulated
arc radiotherapy using these modalities in homogenous and heterogeneous conditions
with a large treatment field applied to a large region of homogeneous media. There
were larger systematic differences in heterogeneous conditions with a small treatment
field because of differences in heterogeneity correction with the different dose calculation
algorithms of the primary TPS and verification program.
Keywords
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Article info
Publication history
Accepted:
November 15,
2018
Received in revised form:
August 31,
2018
Received:
April 16,
2018
Identification
Copyright
© 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
