Feasibility of Using Machine Performance Check-enhanced Couch Check as a Daily Surrogate for Multisphere Winston-Lutz...

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiosurgery Technology

Background:

• Single-isocenter multitarget stereotactic radiosurgery (SIMT SRS) demands high geometric accuracy.
• Winston-Lutz (WL) testing is the established standard for stereotactic verification but is time-consuming.
• Alternative methods for routine geometric accuracy checks are needed to streamline clinical workflows.

Purpose of the Study:

• To assess Varian's machine performance check (MPC)-enhanced couch check as a potential substitute for WL testing.
• To compare the geometric accuracy measurements between WL tests and MPC-enhanced couch checks in clinical practice.
• To determine if MPC can reliably verify isocenter and couch rotation within SIMT SRS tolerances.

Main Methods:

• Geometric agreement was evaluated between WL tests and MPC-enhanced couch check data.
• WL tests were conducted using a multisphere VisionRT phantom over 23 SRS/SRT treatment days.
• Pearson correlation and Bland-Altman analysis were used to compare WL measurements with MPC-max and MPC-shift values.

Main Results:

• High correlation (r > 0.85) was observed between WL and MPC metrics.
• MPC-max and MPC-shift showed minimal bias (+0.033 mm and +0.037 mm, respectively).
• The 95% limits of agreement were within ±0.25 mm, meeting SIMT SRS geometric tolerances.

Conclusions:

• MPC-enhanced couch check demonstrates strong agreement with WL measurements.
• MPC serves as a practical and accurate surrogate for WL testing in SIMT SRS.
• This supports the integration of MPC for frequent isocenter and couch-rotation verification in clinical SRS workflows.