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Updated: Apr 11, 2026
Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
Periodic intrafraction image-guided focal dose-escalated stereotactic body radiotherapy for prostate carcinoma on a
Marco Serpa1, Rolf Wiehle1, Thomas Rothe1
1Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Robert-Koch-Str. 3, 79106, Germany.
Background And Purpose:
Intrafraction motion degrades the efficacy of radiation therapy. We reported on the implementation of focal dose-escalated stereotactic body radiation therapy (HypoFocal-SBRT) for prostate carcinoma on standard linear accelerator, and assessed whether periodic intrafraction image guidance (PIF-IG) improved the accuracy of treatment.
Materials And Methods:
Twenty prostate cancer patients underwent HypoFocal-SBRT. Treatment planning prioritized plan robustness and efficiency accommodating image guidance as-needed for treatment on standard accelerator. A three-dose level planning target volume (PTV) SBRT regime with focal boost was prescribed: PTV30 (seminal vesicles), PTV35 (prostate), and PTV40-42 (intraprostatic tumor lesion) in 5 fractions. Fiducial marker-based PIF-IG, triggered at pre-defined imaging control point(s) (ICPs), was performed using 1 mm (translations)/1° (rotations) action thresholds for online couch corrections. Applied marker registration values were compared to estimated ground-truth, as well as simulated treatment with no PIF-IG and effect on delivered dose estimated.
Results:
Interventions occurred at least once in 95% of patients and 83% of fractions. PIF-IG reduced the geometric uncertainty (root-mean-square error) from 1.6 mm, 2.3 mm, and 2.2 mm for the left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions to 0.6 mm, 0.9 mm, and 0.8 mm, respectively. With PIF-IG, target volumes D98% doses with 5% less than planned were observed in 2% of fractions for PTV30 and PTV35, and 0% for PTV40-42, compared to 16%, 12%, and 6% without PIF-IG.
Conclusions:
Focal dose-escalated SBRT for prostate cancer can be efficiently and accurately performed on standard accelerator. PIF-IG improved the geometric and delivered dose accuracy.
