Novalis intensity-modulated radiosurgery: methods for pretreatment planning.
Randy L Jensen1, Merideth M Wendland, Shyh-Shi Chern
1Department of Neurosurgery, The Huntsman Cancer Institute, University of Utah Health Sciences Center, Salt Lake City, Utah, USA. randy.jensen@hsc.utah.edu
Neurosurgery
|July 17, 2008
Summary
Preprocedure planning for intensity-modulated stereotactic radiosurgery (IMRS) streamlines treatment for cranial base tumors near the optic apparatus. This method improves patient comfort and physician efficiency while ensuring safe radiation doses.
Area of Science:
- Radiation Oncology
- Neurosurgery
- Medical Physics
Background:
- Novalis stereotactic radiotherapy enables precise cranial base tumor treatment.
- Proximity to optic nerve/chiasm necessitates dose limitation, often requiring intensity-modulated stereotactic radiosurgery (IMRS).
- IMRS planning is time-intensive, posing challenges for same-day treatment.
Purpose of the Study:
- To describe methods and results of preprocedure planning for IMRS.
- To manage patients with cavernous sinus/parasellar lesions where optic apparatus dose may exceed 8 Gy.
- To optimize IMRS for efficiency and patient comfort.
Main Methods:
- Patients with lesions near optic pathways considered for IMRS if standard radiosurgery posed dose concerns.
- Fused CT/MRI imaging analyzed using BrainLAB BrainScan 5.3.
- Evaluated dynamic conformal arc and IMRS plans using dose-volume histograms and conformality index.
Main Results:
- IMRS enabled higher therapeutic doses (20-31 Gy) compared to dynamic conformal arc (7.7-20.64 Gy) while respecting optic apparatus dose limits (≤8 Gy).
- Five of six patients required IMRS to avoid exceeding optic nerve tolerance.
- Tumors remained stable post-treatment (mean follow-up 30 months) with no complications.
Conclusions:
- Pretreatment planning technique streamlines IMRS process.
- Enhances patient comfort and optimizes physician time.
- Facilitates safe and effective radiosurgery for complex cranial base tumors.
