Evaluating stereotactic accuracy with patient-specific MRI distortion corrections for frame-based radiosurgery

Area of Science:

• Medical Physics
• Radiotherapy
• Neuro-oncology

Background:

• Frame-based stereotactic radiosurgery (SRS) relies on accurate imaging for precise target delineation.
• Geometric distortions in Magnetic Resonance Imaging (MRI) can compromise treatment accuracy.
• Assessing and correcting these distortions is crucial for optimizing SRS outcomes.

Purpose of the Study:

• To investigate the impact of MRI distortions on frame-based SRS treatments.
• To evaluate the necessity of clinical distortion correction for SRS.
• To assess the efficacy of the Cranial Distortion Correction (CDC) algorithm.

Main Methods:

• 18 patients with 80 brain targets underwent frame-based SRS.
• Cranial Distortion Correction (CDC) software was used to correct MRI distortions.
• Planning Target Volumes (PTVs) were compared before and after correction (PTV_ORIG, PTV_CORR, PTV_RECON).
• Dosimetric parameters (Dmin, D95%) and normal tissue doses (V12Gy, V10Gy, V5Gy) were analyzed.

Main Results:

• Corrected PTVs (PTV_CORR) showed significantly different dosimetric changes compared to uncorrected re-contoured PTVs (PTV_RECON).
• A uniform 1 mm PTV expansion did not fully cover all corrected targets.
• CDC algorithm significantly improved target delineation accuracy and reduced dosimetric deviations.

Conclusions:

• MRI distortions present a significant challenge in frame-based SRS target delineation.
• The CDC algorithm offers a viable solution for mitigating MRI distortions.
• Implementing distortion correction enhances treatment precision and dosimetric accuracy in SRS.