Intensity modulated stereotactic radiosurgery using a micro-multileaf compared with gamma knife and linac arc radiosurgery

Albert DeNittis, MD
OncoLink Assistant Editor
Last Modified: November 1, 1999

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Presenter: Wu QJ
Affiliation: Case Western Reserve University

Stereotactic radiosurgery is delivered with the use of gamma knife or linac based photon beams. Both of these modalities can provide an acceptable dose distribution. However, they are time consuming. The development of micro-multileaf collimators (mMLC) and intensity modulation has allowed a potential for static intensity-modulated (IM) linac delivered radiotherapy.

Three seperate targets were compared and contrasted for treatment optimization. Five arc linac based, seven conformal based, and seven IM treatment fields were studied. All plans were optimized to the 18 Gy prescription dose and dose volume histograms of the target and normal tissues were analyzed.


  • For small spherical targets (<3 cm) all modalities provide adequate coverage.
  • For irregularly shaped targets, linac based fields including IM provide better dose distribution.
  • IM based treatment can also optimize dose to critical structures
Clinical/Scientific Implications:
  • Linac based IM radiosurgery can be optimized to deliver conformal doses to simple and complex target shapes.
  • The complexity of treatment was not increased with this method.

ASTRO coverage is sponsored, in part, by Varian Medical Systems, Inc.

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