Impact of the high-definition multileaf collimator on linear accelerator-based intracranial stereotactic radiosurgery

J. A. Tanyi, C. M. Kato, Y. Chen, Z. Chen, M. Fuss

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Abstract

Objectives: The impact of two multileaf collimator (MLC) systems for linear accelerator-based intracranial stereotactic radiosurgery (SRS) was assessed. Methods: 68 lesions formed the basis of this study. 2.5 mm leaf width plans served as reference. Comparative plans, with identical planning parameters, were based on a 5 mm leaf width MLC system. Two collimation strategies, with collimation fixed at 0° or 90° and optimised per arc or beam, were also assessed. Dose computation was based on the pencil beam algorithm with allowance for tissue heterogeneity. Plan normalisation was such that 100% of the prescription dose covered 95% of the planning target volume. Plan evaluation was based on target coverage and normal tissue avoidance criteria. Results: The median conformity index difference between the MLC systems ranged between 0.8% and 14.2%; the 2.5 mm MLC exhibited better dose conformation. The median reduction of normal tissue exposed to ≥100%, ≥50% and ≥25% of the prescription dose ranged from 13.4% to 29.7%, favouring the 2.5 mm MLC system. Dose fall-off was steeper for the 2.5 mm MLC system with an overall median absolute difference ranging from 0.4 to 1.2 mm. The use of collimation optimisation resulted in a decrease in differences between the MLC systems. The results demonstrated the dosimetric merit of the 2.5 mm leaf width MLC system over the 5 mm leaf width system, albeit small, for the investigated range of intracranial SRS targets. Conclusion: The clinical significance of these results warrants further investigation to determine whether the observed dosimetric advantages translate into outcome improvements.

Original languageEnglish (US)
Pages (from-to)629-638
Number of pages10
JournalBritish Journal of Radiology
Volume84
Issue number1003
DOIs
StatePublished - Jul 1 2011

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ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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