Highlights
- •Plan complexity of a national IMRT/VMAT audit was evaluated and compared.
- •Principal component analysis was used to obtain a global plan complexity score.
- •The global score highlighted differences in complexity between technology/technique.
- •The proposed methodology can be applied to any given plans set.
- •The resulting scores may be used to compare the complexity among the plans set.
Abstract
Purpose
This work aimed to characterize and compare the complexity of the plans created in
the context of a national IMRT/VMAT audit. A plan complexity score is proposed to
summarize all the evaluated complexity features.
Materials and methods
Nine complexity metrics have been computed for the audit plans, evaluating different
complexity aspects. An approach based on Principal Component Analysis was followed
to explore the correlation between the metrics and derive a smaller set of new uncorrelated
variables (principal components, PCs). The resulting PCs were then used to calculate
a plan complexity score. Plan quality was also assessed and the correlation between
plan complexity, quality and deliverability investigated using the Spearman's rank
correlation coefficient.
Results
The first two PCs explained over 90% of the total variance in the original dataset.
Their representation allowed to identify patterns in the data, namely a clear separation
between plans created using different technologies/techniques. The calculated plan
complexity score quantified these differences. Sliding window Eclipse plans were found
to be the most complex and VMAT Eclipse group presented the highest complexity variability,
for the evaluated parameters. Concerning plan quality, no differences between treatment
technology/technique have been identified. However, plans with larger number of monitor
units tended to be associated with higher deviations between calculated and measured
doses.
Conclusions
The proposed plan complexity score allowed to summarize the differences not only inter-
but also intra-groups of technologies/techniques, paving the way for improvement of
the planning strategies at the national level through knowledge sharing.
Keywords
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Article info
Publication history
Published online: January 23, 2020
Accepted:
January 14,
2020
Received in revised form:
January 8,
2020
Received:
September 5,
2019
Identification
Copyright
© 2020 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
