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. 2019;6(3):227-233.

A standardised method for use of the Leksell GammaPlan Inverse Planning module for metastases

Peter Fallows  1 , Gavin Wright  1 , Peter Bownes  1
Affiliations

A standardised method for use of the Leksell GammaPlan Inverse Planning module for metastases

Peter Fallows et al. J Radiosurg SBRT. 2019.

Abstract

Aim: The aim of this investigation was to develop a standardised method for using the inverse planning module in Leksell GammaPlan.

Methods: Leksell GammaPlan version 10 and higher contains an inverse planning module, consisting of functions to automatically fill a target volume with shots and subsequently optimise their resulting dosimetry. A standardised method for using the inverse planning module was developed for metastases, using the following optimisation parameter weightings: {coverage 0.9, selectivity 0.1, gradient index (GI) 0.2, }. 25 plans produced using these parameters were compared to manually produced clinical plans. Additionally, the 25 plans were manually adjusted to match the coverage of the clinical plans, and comparison of the PCI, GI and BOT was made.

Results: The average parameters for plans produced using the optimisation module were; coverage 98.7%; Paddick conformity index (PCI) 0.85; GI 2.75, compared to coverage 99.5%; PCI 0.83; GI 2.70 for manual clinical plans with BOT 21% shorter than clinical plans on average. The average parameters for the plans produced by the optimisation module after manual adjustment to match the coverage of the clinical plans were: coverage 99.5, PCI 0.83, GI 2.73 with BOT 16% shorter than clinical plans on average.

Conclusions: The standardised method for using the optimisation module has potential for shortening treatment times and planning times.

Keywords: Gamma Knife; inverse planning; optimiser; stereotactic radiosurgery.

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Conflict of interest statement

Authors’ disclosure of potential conflicts of interest Dr. Wright reports personal fees received by his employer from Elekta Instruments AB, Stockholm, Sweden, outside the submitted work. Dr Wright attended user group meetings of early Icon adopters organized by and hosted by Elekta. Furthermore, Dr Wright participated in work for Elekta validating developments and new software releases for Icon and GammaPlan, for which payments have been received by his employer from Elekta. Elekta has not been involved in any way in the compilation of this manuscript, nor does the company have any knowledge of the work described in this manuscript. Peter Fallows and Peter Bownes have nothing to disclose.

Figures

Figure 1
Figure 1
The definition of Grad is shown in the top image. Gradient indices above 2.6 are penalised (this has been changed to 2,3 in versions 11.0.2 and later). The definition of the Time parameter is shown in the bottom image. Tref is defined as the BOT at the start of the optimisation.
Figure 2
Figure 2
Recommended initial number of 16mm shots.
Figure 3
Figure 3
Recommended initial number of 8mm shots.
Figure 4
Figure 4
Recommended initial number of 4mm shots.
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See this image and copyright information in PMC

References

    1. Inverse Planning in Leksell GammaPlan 10 , Elekta Instrument AB, 2010
    1. Elekta , Release Notes for Leksell Gammaplan 11.0.2, doc 1521809 rev1, 2016
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    1. Wright G, Hatfield P, Loughrey C, Reiner B, Bownes P, St James’s Institute of Oncology, St James’s University Hospital, Leeds A method for scoring treatment time efficiency of Gamma Knife radiosurgical treatment plans for brain metastases, Medical Physics 2013;40(2) - PubMed

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