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Stereotactic Radiosurgery for Gynecologic Cancer
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Multicenter End-to-End Evaluation of Single-Isocenter Multitarget Stereotactic Radiosurgery Approaches: Accuracy and
Benedikt Thomann1, Tobias Fechter1, Johannes Fischer2
1Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site DKTK-Freiburg, Germany.
Summary
Single-isocenter multitarget stereotactic radiosurgery (SIMT SRS) spatial accuracy is mainly dependent on imaging-isocenter consistency (ICC). Automated planning tools significantly improve treatment plan quality and standardization in SIMT SRS.
Area of Science:
- Medical Physics
- Radiotherapy
- Neurosurgery
Background:
- Single-isocenter multitarget stereotactic radiosurgery (SIMT SRS) enables efficient treatment of multiple brain metastases.
- End-to-end testing is crucial for assessing the accuracy and quality of SIMT SRS delivery.
- Variability in institutional protocols can impact treatment outcomes.
Purpose of the Study:
- To dosimetrically evaluate end-to-end test results for SIMT SRS.
- To identify factors influencing spatial accuracy and treatment plan quality in SIMT SRS.
- To compare different approaches and techniques used in multicenter SIMT SRS protocols.
Main Methods:
- A multicenter study involving 23 institutions in Germany, Austria, and Switzerland.
- Use of an anthropomorphic head phantom with radiochromic film and polymer gel inserts.
- Quantification of spatial accuracy by comparing planned and measured isodose centroids.
- Assessment of plan quality using Paddick gradient index (GI) and conformity index (PCI).
Main Results:
- Mean spatial offset was 0.9 ± 0.4 mm; 33% of centers exceeded 1 mm.
- Higher imaging-to-radiation isocenter consistency (ICC) correlated with improved spatial accuracy (p=0.002).
- Automated planning (AP) tools significantly improved GI (4.9 vs. 8.1, p=0.015) and PCI (0.83 vs. 0.68, p=0.028) compared to conventional planning.
Conclusions:
- Spatial accuracy in SIMT SRS is primarily determined by ICC, highlighting the need for precise imaging isocenter calibration.
- Automated planning tools enhance and standardize treatment plan quality across different centers.
- Delivery infrastructure and specific techniques had less influence on spatial accuracy compared to ICC.
