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A comparison of three stereotactic radiotherapy techniques; ARCS vs. noncoplanar fixed fields vs. intensity
R M Cardinale1, S H Benedict, Q Wu
1Department of Radiation Oncology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA.
International Journal of Radiation Oncology, Biology, Physics
|October 27, 1998
Summary
Intensity-modulated radiation therapy (IMRT) improves dose conformity and reduces normal brain radiation for irregular brain tumors compared to traditional arc-based methods. This technique offers a better therapeutic ratio for complex intracranial targets.
Area of Science:
- Radiation Oncology
- Neurosurgery
- Medical Physics
Background:
- Linac arc-based stereotactic radiotherapy is increasingly used for brain tumors.
- Circular collimators are optimal for small, spherical targets.
- Noncoplanar or intensity-modulated beams may improve treatment for irregular or large tumors.
Purpose of the Study:
- Compare dose conformity and normal brain dose characteristics of three stereotactic techniques.
- Evaluate techniques for various nonspherical target shapes.
Main Methods:
- Compared three stereotactic techniques: noncoplanar arcs (ARCS), fixed noncoplanar fields (3D), and intensity-modulated radiation therapy (IMRT).
- Used three intracranial targets: ellipsoid, hemisphere, and irregular tumor.
- Performed dose volume histograms for each target/technique combination.
Main Results:
- For ellipsoid targets, dose conformity was similar across techniques; ARCS showed more favorable normal brain isodose distributions.
- For hemisphere and irregular tumor targets, IMRT demonstrated superior dose conformity and reduced normal brain volumes in high/low isodose regions.
Conclusions:
- IMRT provides improved dose conformity and decreased nontarget brain dose for hemisphere and irregular intracranial targets compared to ARCS and 3D techniques.
- IMRT may enhance the therapeutic ratio for stereotactically treated large and/or irregularly shaped brain tumors.