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Simulation-Free Adaptive Prostate Stereotactic Body Radiation Therapy on Magnetic Resonance-Linac: Technical
Nicolas Côté1, Sun Lian2, Himanshu Nagar2
1Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York; Department of Physics, Université de Montréal, Montréal, Quebec, Canada.
Summary
Simulation-free workflows streamline prostate cancer radiotherapy on MR-Linac, eliminating the need for simulation scans. These advanced methods ensure plan quality and improve patient access for adaptive stereotactic body radiation therapy (SBRT).
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Technology
Background:
- Stereotactic body radiotherapy (SBRT) for prostate cancer requires precise patient setup.
- Magnetic Resonance (MR)-Linac systems offer real-time imaging for adaptive radiotherapy.
- Traditional workflows involve simulation scans, adding time and resources.
Purpose of the Study:
- To develop and evaluate two simulation-free (SF) workflows for prostate SBRT on an MR-Linac.
- To assess the feasibility of using diagnostic MR reference scans or template scans for SF planning.
- To compare the dosimetric quality and efficiency of SF workflows against standard clinical practice.
Main Methods:
- Derived population-based relative electron density (RED) values from 100 prostate SBRT patients.
- Evaluated two SF approaches in an independent cohort: diagnostic MR scan and template scan.
- Assessed Artificial Intelligence (AI)-generated contours using surface Dice (sDSC) and Added Path Length (APL).
- Performed Failure Modes and Effects Analysis (FMEA) to identify and mitigate risks.
Main Results:
- Population-based RED assignments showed mean dose differences under 1%.
- AI contours demonstrated strong agreement with physician contours (e.g., sDSC of 0.99 for rectum).
- SF adaptive plans were clinically comparable to standard workflow plans in dose metrics and monitor unit (MU) usage.
- The diagnostic MR SF workflow has been clinically implemented, treating 22 patients successfully.
Conclusions:
- Simulation-free workflows effectively streamline adaptive prostate SBRT on MR-Linac without compromising plan quality.
- Both diagnostic MR and template-based SF approaches are viable alternatives to traditional simulation.
- The template-based workflow enhances patient access by removing imaging prerequisites.
