Prospective Evaluation of the Clinical Benefits of a Novel Tattoo-less Workflow for Nonspine Bone Stereotactic Body Radiation Therapy: Integrating Surface-Guidance With Triggered Imaging Reduces Treatment Time and Eliminates the Need for Tattoos

Abstract

ObjectiveOligometastatic disease has expanded the indications for non-spine bone stereotactic body radiation therapy (NSB SBRT). We investigated whether optical surface monitoring systems (OSMS) could enable tattoo-less set up and substitute for 2D-3D or cone beam computed tomography (CBCT)-based mid-imaging in NSB SBRT. Materials/MethodsOSMS was incorporated in parallel with an existing workflow using pre-treatment CBCT and mid 2D-3D kV/kV imaging beginning 11/2019. The ability of OSMS to detect out-of-tolerance (>2mm/>2°) and commanded couch shifts was analyzed. A workflow incorporating OSMS reference captures, CBCT for pre-treatment verification and OSMS/triggered imaging (TI) for intrafraction monitoring was developed for rib/sternum SBRT beginning 11/2021 and all NSB SBRT beginning 2/2022. Treatment time and CBCT-related radiation dose between the OSMS and the non-OSMS intrafraction monitoring group was analyzed pre and post-OSMS/TI workflow adoption. All fractions were analyzed through statistical process control (SPC) with use of an XmR chart of treatment time per quarter from 2/2019 to 2/2023. Special cause rules were based on Institute for Healthcare Improvement criteria. ResultsFrom 2/2019 to 2/2023, 1993 NSB SBRT fractions were delivered, including 234 rib, 109 sternum, 214 ilium, and 682 multi-site. Over 20 commanded shifts, OSMS could detect 2mm shifts to within 0.4mm 67% of the time and 0.8mm 95% of time. All NSB SBRT sites showed significant reductions in treatment time, including the greatest improvement in rib total treatment (21.6 to 13.4 minutes, p=1.16*10−17) and beam time (7.9 to 3.2 minutes, p= 7.32*10−27). Significant reductions in CBCT-related radiation were also observed for several NSB sites. These process improvements were associated with OSMS adoption. ConclusionAdoption of a novel NSB SBRT workflow incorporating OSMS/TI for bone intrafraction motion monitoring reduced treatment time and CBCT-related radiation exposure while also allowing for more continuous intrafraction motion monitoring for NSB SBRT. OSMS/TI enabled the transition to a tattoo-less workflow.