Highlights
- •Use of VMAT technique for radiosurgery.
- •Comparison of VMAT and 3D-conformal arc therapy for radiosurgery.
- •Influence of the MLC leaf size on the dosimetric quality of the technique.
Abstract
Purpose
To study the influence of Multileaf Collimator (MLC) leaf width in radiosurgery treatment
planning for Volumetric Modulated Arc Therapy (VMAT) and 3D Dynamic Conformal Arc
Therapy (3D-DCA).
Material and methods
16 patients with solitary brain metastases treated with radiosurgery via the non-coplanar
VMAT were replanned for the 3D-DCA. For each planning technique two MLC leaf width
sizes were utilized, i.e. 5 mm and 2.5 mm. These treatment plans were compared using
dosimetric indices (conformity, gradient and mean dose for brain tissue) and the normal
tissue complication probability (NTCP).
Results
An improvement in planning quality for VMAT was observed versus 3D-DCA for any MLC
leaf width, mainly with regards to dose conformity and to a lesser extent regards
dose gradient. No significant difference was observed for any of both techniques using
smaller leaf width. However, dose gradient was improved in favor of the 2.5 mm MLC
for either of both techniques (15% VMAT and 10% 3D-DCA); being noticeable for lesions
smaller than 10 cm3. Nonetheless, the NTCP index was not significantly affected by variations in the
dose gradient index.
Conclusions
This, our present study, suggests that the use of an MLC leaf width of 2.5 mm via
the noncoplanar VMAT and 3D-DCA techniques provides improvement in terms of dose gradient
for small volumes, over those results obtained with an MLC leaf width of 5 mm. The
3D-DCA does also benefit from MLC leaf widths of a smaller size, mainly in terms of
conformity.
Keywords
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Article info
Publication history
Published online: February 18, 2015
Accepted:
January 20,
2015
Received in revised form:
January 19,
2015
Received:
October 30,
2014
Identification
Copyright
© 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Inc. All rights reserved.
