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Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
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Single-Isocenter Multiple-Target Stereotactic Radiosurgery: Risk of Compromised Coverage
Justin Roper1, Vorakarn Chanyavanich1, Gregory Betzel1
1Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, Georgia; Department of Biostatistics and Bioinformatics, Winship Cancer Institute of Emory University, Atlanta, Georgia.
International Journal of Radiation Oncology, Biology, Physics
|October 14, 2015
Summary
Rotational errors in stereotactic radiosurgery (SRS) can compromise target coverage, especially with larger errors or smaller targets. This study quantifies these effects, providing models to predict dosimetric impacts based on patient-specific parameters.
Area of Science:
- Radiation Oncology
- Medical Physics
- Neurosurgery
Background:
- Stereotactic radiosurgery (SRS) requires precise radiation delivery.
- Volumetric modulated arc therapy (VMAT) is a common SRS technique.
- Rotational errors can occur during SRS delivery, potentially affecting treatment accuracy.
Purpose of the Study:
- To evaluate the impact of rotational errors on target coverage in multi-target SRS using VMAT.
- To identify factors influencing the dosimetric effects of rotational errors.
Main Methods:
- Retrospective analysis of 50 SRS cases with two intracranial planning target volumes (PTVs).
- Simulated rotational errors (0.5°, 1.0°, 2.0°) applied to VMAT plans.
- Assessed dose to 95% of PTV (D95) and volume receiving 95% of dose (V95) for target coverage.
- Multivariate analysis used to correlate coverage with PTV volume, separation, and rotational error.
Main Results:
- 0.5° rotational error showed no impact on D95 or V95.
- 1.0° rotational error reduced coverage below 95% in 7% of targets.
- 2.0° rotational error decreased coverage to >95% in only 63% of targets.
- PTV volume and distance to isocenter were significant predictors of target coverage.
Conclusions:
- Rotational errors significantly impact target coverage in VMAT SRS.
- Coverage risk increases with smaller PTV volumes, larger rotational errors, and greater target separation.
- Developed models can predict dosimetric effects of rotational errors using patient-specific data.
