Is Simulation-free RT in Our Future?

Presenting author: Yasamin Sharifzadeh, MD

Simulation-free radiation therapy has been increasingly adopted to expedite treatment planning by omitting traditional CT simulation and instead relying on diagnostic imaging, particularly in palliative settings. Recent advances in high-quality cone-beam CT (CBCT) and online adaptive treatment technologies have enabled accurate dose calculation and rapid plan adaptation to daily anatomy, respectively; hence, making simulation-free workflows clinically achievable.

This study, presented by Yasamin Sharifzadeh, MD, Mayo Clinic Rochester, demonstrates a direct-to-unit (DtU) adaptive SBRT workflow that eliminates CT simulation by using diagnostic PET-CT for treatment planning and daily CBCT for adaptation. In 34 patients (41 treatment sites, primarily prostate bone metastases), adaptive plans consistently improved target coverage and/or OAR sparing compared with scheduled plans, all within a streamlined 45-minute in-room process. Early outcomes showed a 64% complete metabolic response, 97% 12-month overall survival, and strong feasibility for patients living far from treatment centers. This approach reduces travel and logistical burden while maintaining high clinical quality. With advances in adaptive therapy and treatment planning, the study demonstrates that “direct-to-unit radiation therapy enables safe, effective delivery of high-dose radiation — including stereotactic body radiation therapy (SBRT) — while streamlining care for both patients and providers."

The DtU SBRT strategy addresses several patient- and system-level challenges: eliminating a separate simulation visit, minimizing travel requirements and streamlining workflow without compromising local control. While follow-up remains relatively short and the study population consisted predominantly of male prostate cancer patients, the findings highlight the feasibility and clinical value of leveraging diagnostic imaging for adaptive SBRT, particularly for patients residing at a distance from treatment facilities.

Abstract 220, Direct-to-Unit Stereotactic Body Radiation Therapy Utilizing Adaptive Planning, was presented during the SS 20 - Patient Safety 1: Harnessing AI and Team Efforts to Enhance Patient Care Through Workflow and Automation Improvements session at the 67th ASTRO Annual Meeting.