Performance assessment of surgical tracking systems based on statistical process control and longitudinal QA

Abstract

A system for performance assessment and quality assurance (QA) of surgical trackers is reported based on principles of geometric accuracy and statistical process control (SPC) for routine longitudinal testing. A simple QA test phantom was designed, where the number and distribution of registration fiducials was determined drawing from analytical models for target registration error (TRE). A tracker testbed was configured with open-source software for measurement of a TRE-based accuracy metric (Formula presented.) and Jitter ((Formula presented.)). Six trackers were tested: 2 electromagnetic (EM–Aurora); and 4 infrared (IR − 1 Spectra, 1 Vega, and 2 Vicra)–all NDI (Waterloo, ON). Phase I SPC analysis of Shewhart mean ((Formula presented.)) and standard deviation ((Formula presented.)) determined system control limits. Phase II involved weekly QA of each system for up to 32 weeks and identified Pass, Note, Alert, and Failure action rules. The process permitted QA in <1 min. Phase I control limits were established for all trackers: EM trackers exhibited higher upper control limits than IR trackers in (Formula presented.) (EM: (Formula presented.) 2.8–3.3 mm, IR: (Formula presented.) 1.6–2.0 mm) and Jitter (EM: (Formula presented.) 0.30–0.33 mm, IR: (Formula presented.) 0.08–0.10 mm), and older trackers showed evidence of degradation–e.g. higher Jitter for the older Vicra (p-value