PURPOSE: The time structures of proton spot delivery in proton pencil beam scanning (PBS) radiation therapy are essential in many clinical applications. This study aims to characterize the time structures of proton PBS delivered by both synchrotron and synchrocyclotron accelerators using a non-invasive technique based on scattered particle tracking. METHODS: A pixelated semiconductor detector, AdvaPIX-Timepix3, with a temporal resolution of 1.56 ns, was employed to measure time of arrival of secondary particles generated by a proton beam. The detector was placed laterally to the high-flux area of the beam in order to allow for single particle detection and not interfere with the treatment. The detector recorded counts of radiation events, their deposited energy and the timestamp associated with the single events. Individual recorded events and their temporal characteristics were used to analyze beam time structures, including energy layer switch time, magnet switch time, spot switch time, and the scanning speeds in the x and y directions. All the measurements were repeated 30 times on three dates, reducing statistical uncertainty. RESULTS: The uncertainty of the measured energy layer switch times, magnet switch time, and the spot switch time were all within 1% of average values. The scanning speeds uncertainties were within 1.5% and are more precise than previously reported results. The measurements also revealed continuous sub-milliseconds proton spills at a low dose rate for the synchrotron accelerator and radiofrequency pulses at 7 µs and 1 ms repetition time for the synchrocyclotron accelerator. CONCLUSION: The AdvaPIX-Timepix3 detector can be used to directly measure and monitor time structures on microseconds scale of the PBS proton beam delivery. This method yielded results with high precision and is completely independent of the machine log files.

• Klíčová slova
• dose rate, pencil beam scanning, proton therapy, scanning speeds, semiconductor detectors, time structure,
• MeSH
• časové faktory MeSH
• částice - urychlovače * přístrojové vybavení   MeSH
• celková dávka radioterapie * MeSH
• lidé MeSH
• nádory radioterapie   MeSH
• plánování radioterapie pomocí počítače * metody   MeSH
• polovodiče * MeSH
• protonová terapie * přístrojové vybavení   MeSH
• protony MeSH
• synchrotrony přístrojové vybavení   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• protony MeSH