KEY POINTS
- Detector development study evaluating a thick gas electron multiplier-based air ionization chamber for online dose monitoring in both conventional radiotherapy and ultra-high dose rate FLASH radiotherapy.
- In conventional radiotherapy testing, the detector showed a nearly identical linear response to the PTW Farmer 30013 ionization chamber over 1-100 Gy, with dose deviations within ±3% and an operational plateau of approximately 400 V.
- Under ultra-high dose rate conditions, the detector maintained an operational plateau of about 200 V and showed dose-response linearity >99% versus EBT3 film at dose rates up to 250 Gy/s.
- The device could resolve FLASH accelerator macro-pulse structures and perform dose integration using positive ion signals, supporting potential use in real-time FLASH dose monitoring.
- Important limitations remain: accuracy at typical clinical single-field doses for intensity modulated or fractionated treatments was not established, and dose-rate dependence was observed between 50 and 250 Gy/s under ultra-high dose rate conditions.
CLINICAL TAKEAWAY
This study addresses a real bottleneck for FLASH translation: reliable online dosimetry across both conventional and ultra-high dose rate regimes. The detector performance is technically promising, but this remains preclinical detector validation; dose-rate dependence, clinical-dose accuracy, calibration robustness, and broader beam-condition testing need further work before clinical implementation.
SOURCE
International Journal of Radiation Oncology, Biology, Physics