Framework for the quantitative assessment of adaptive radiation therapy protocols

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Adaptive radiation therapy (ART) utilizes flags like body contour changes to guide treatment replanning in head and neck cancer (HNC) patients.
• Current ART flagging methods lack quantitative validation, particularly simple, widely adopted protocols.
• A need exists to verify the accuracy of identifying patients who would benefit from replanned HNC treatment.

Purpose of the Study:

• To propose and demonstrate a quantitative framework for evaluating the accuracy of ART replan candidate identification.
• To assess the clinical effectiveness of a specific ART flag: body contour change exceeding 1.5 cm.

Main Methods:

• Established ground truth replan criteria through a survey of HNC radiation oncologists.
• Generated 'synthetic CTs' from weekly CBCT images to approximate patient-specific dose deviations.
• Compared clinical ART flagging with ground truth criteria using truth table analysis on 15 HNC patients.

Main Results:

• Physicians prioritized geometric shifts of high-dose volumes over simple contour changes.
• The body contour flag demonstrated poor sensitivity (0%-28%) in identifying major violations based on expert criteria.
• The proposed framework revealed a significant discrepancy between clinical flagging and true replan needs.

Conclusions:

• Healthcare centers should develop and implement ground truth criteria to validate existing ART protocols.
• The presented framework can facilitate the testing and identification of more effective ART replan flags.
• Improved ART flagging accuracy can enhance clinical resource allocation and positively impact patient outcomes.