Clinical Impact of Targeting Inaccuracy Due to Distortion of the Leksell Stereotactic Frame

Cécile Renier,Nicolas Massager

doi:10.4236/ojmn.2018.83026

Abstract

Background: Distortion of the Leksell stereotactic frame can occur during surgical and radiosurgical frame-based procedures. The targeting accuracies of surgical procedures such as DBS surgery or frame-based biopsy, or Gamma Knife radiosurgical procedures, are related to the stereotactic frame that is commonly referred to a non-deformable referential system. Objective: To evaluate the clinical impact of frame distortion on accuracy of targeting in various stereotactic procedures. Methods: We studied the influence of increasing levels of distortion of the Leksell frame both on surgical procedures using the stereotactic arch, and on radiosurgical procedures with the Gamma Knife. For surgical procedures we applied the Target Simulator of Elekta to a frame submitted to different levels of frame distortion, and we measured the modifications of accuracy of targeting. For radiosurgical procedures the Leksell frame was applied on an anthropomorphic phantom and modifications of target coordinates were measured by an imaging method using the stereotactic CBCT of the Gamma Knife ICON. Results: For surgical procedures, we found a linear relation between the amount of the frame distortion and the extent of the deviation from the stereotactic target using the stereotactic arch (R2 = 0.99709). The level of bending of the frame is also linearly related to the level of inaccuracy of stereotactic targeting based on acquisition of MRI and CTscan with the Elekta imaging boxes (R2 = 0.96825). The inaccuracy of targeting related to frame bending can be avoided by a systematic control at the end of frame placement and by the use of the CBCT of the Gamma Knife Icon. Conclusion: Distortion of the frame is a significant source of clinical inaccuracy of targeting for stereotactic procedures. Frame bending must be checked after each frame placement and corrected if needed to avoid targeting inaccuracy during stereotactic surgery and radio-surgery procedures.

Highlights

We have observed, as other, in our clinical daily practice that the pressure exerted on the fixation screws to secure the frame on the patient’s head can create a significant distortion of the Leksell head frame [1] [2]
Does frame bending really induce a problematic inaccuracy in stereotactic targeting for surgical procedures such as DBS surgery or frame-based biopsy, or for Gamma Knife radiosurgical procedures? Different referential systems were applied on the frame for these procedures
The aim of our work was to study the clinical impact of targeting inaccuracy produced by distortions of the Leksell frame when applied in various stereotactic conditions

Summary

Introduction

As other, in our clinical daily practice that the pressure exerted on the fixation screws to secure the frame on the patient’s head can create a significant distortion of the Leksell head frame [1] [2]. Does frame bending really induce a problematic inaccuracy in stereotactic targeting for surgical procedures such as DBS surgery or frame-based biopsy, or for Gamma Knife radiosurgical procedures? The targeting accuracies of surgical procedures such as DBS surgery or frame-based biopsy, or Gamma Knife radiosurgical procedures, are related to the stereotactic frame that is commonly referred to a non-deformable referential system. Methods: We studied the influence of increasing levels of distortion of the Leksell frame both on surgical procedures using the stereotactic arch, and on radiosurgical procedures with the Gamma Knife. For radiosurgical procedures the Leksell frame was applied on an anthropomorphic phantom and modifications of target coordinates were measured by an imaging method using the stereotactic CBCT of the Gamma Knife ICON. Frame bending must be checked after each frame placement and corrected if needed to avoid targeting inaccuracy during stereotactic surgery and radiosurgery procedures

Objectives

Discussion

Conclusion