ExacTrac Dynamic workflow evaluation: Combined surface optical/thermal imaging and X-ray positioning

Area of Science:

• Medical Physics
• Radiotherapy Technology

Background:

• Image guidance is crucial in modern radiotherapy, particularly for stereotactic techniques.
• The ExacTrac Dynamic (EXTD) system integrates surface-guided and image-guided RT for enhanced patient positioning and monitoring.

Purpose of the Study:

• To evaluate the geometric accuracy and clinical workflow of the EXTD system.
• To compare EXTD's surface optical/thermal and stereoscopic X-ray imaging with cone-beam CT (CBCT) and assess congruence with the radiation isocenter.

Main Methods:

• Winston Lutz tests performed over one year to assess accuracy.
• End-to-end positioning tests comparing EXTD systems (stereoscopic X-ray, optical-surface imaging) with CBCT and MV portal imaging.
• Evaluation of 14 patients with intracranial tumors treated using open-face masks.

Main Results:

• Displacements between all tested systems (CBCT, stereoscopic X-ray, optical-surface imaging, MV portal imaging) were within the submillimeter range.
• Limited differences (max 0.02 mm) observed between optical/thermal and stereoscopic X-ray imaging in patient evaluations.
• EXTD demonstrated high accuracy across all couch angles.

Conclusions:

• The EXTD system provides submillimeter geometric accuracy for patient positioning and monitoring in radiotherapy.
• Its optical/thermal positioning system offers comparable accuracy to existing image-guided RT systems.
• The EXTD system is effective for detecting intra-fractional motion and real-time surface tracking during radiotherapy.