Use of surface tracking recordings to identify pitfalls during surface-guided radiotherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Medical Imaging

Background:

• Precise patient positioning is critical for effective radiation therapy.
• Surface-guided radiotherapy (SGRT) systems are increasingly adopted to minimize radiation exposure from traditional imaging methods like cone-beam CT (CBCT).
• The ExacTrac Dynamic system integrates surface imaging and thermography for accurate patient geometry measurement.

Purpose of the Study:

• To prospectively evaluate the advantages, feasibility, and potential pitfalls of SGRT using a prototype system.
• To compare the accuracy of SGRT patient positioning against the standard X-ray-based image-guided radiotherapy (IGRT).

Main Methods:

• Patient surfaces were recorded using a surface camera during positioning and treatment across various tumor sites.
• Surface camera datasets were analyzed to assess patient positioning accuracy.
• Deviations exceeding 5 mm (extracranial) or 2 mm (cranial) were analyzed as potential pitfalls, comparing SGRT data with CBCT shifts.

Main Results:

• 162 displacement vector datasets from 130 patients were evaluated.
• Head and neck regions showed the smallest deviations (mean 1.9 mm/0.8°).
• The pelvic area exhibited the largest mean deviations (4.8 mm translational, 1.1° rotational), with notable longitudinal outliers identified and analyzed.

Conclusions:

• The study highlights the benefits and challenges of SGRT implementation.
• Thorough application of SGRT protocols is essential to overcome identified pitfalls.
• This research provides a practical guide for clinicians using or adopting SGRT for patient positioning.