Abstract
Background and purpose
Helical tomotherapy (HT) can deliver highly conformal, uniform doses to the target
volume. However, HT can only be delivered in a coplanar mode.
The purpose of this study was to perform a dosimetric comparison of HT versus coplanar
(cIMRT) and non-coplanar (n-cIMRT) beam arrangements on a conventional linear accelerator
in a diverse group of brain tumors.
Materials and methods
A total of 45 treatment plans were calculated retrospectively for 15 cases. For each
case, 3 different delivery techniques (n-cIMRT, cIMRT and HT) were used. The treatment
plans were compared using the parameters of the target coverage (conformity index;
CI) and homogeneity (HI) for the planning target volume (PTV) and the maximum and
mean doses for organs at risk (OARs).
Results
Median HI and CI were the best for HT plans and the worst for cIMRT. The largest reduction
of maximum dose for lenses and mean dose for both eyes was achieved for n-cIMRT plans.
Mean dose for chiasm and the ipsilateral optic nerve were the lowest for HT. The contralateral
optic nerve was most spared with n-cIMRT. For D1% in the brain stem, there was no significant difference between HT and the IMRT plans.
Conclusions
Both HT and n-cIMRT are capable of producing conformal and homogeneous treatment plans
with a good sparing of OARs. However, due to the non-coplanar capabilities of IMRT,
n-cIMRT led to a superior dose reduction to the lenses.
Keywords
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Article info
Publication history
Published online: March 07, 2014
Accepted:
February 12,
2014
Received in revised form:
February 10,
2014
Received:
November 2,
2013
Identification
Copyright
© 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Inc. All rights reserved.
