by John R. Fischer
, Senior Reporter | February 09, 2022
Scientists in Vancouver have developed an affordable X-ray tube-based system that incorporates plastic scintillation detectors for the delivery of FLASH radiotherapy.
At roughly 40 Gy/s and above, FLASH can deliver electron, photon or proton radiation at ultrahigh dose rates in less than one second. A full course can be as short as one millisecond. This can decrease damage and toxicity to surrounding healthy tissue, while delivering radiation directly to the tumor.
Designed at the University of Victoria in British Columbia, the system consists of a customized beam shutter for in vitro ultrahigh dose rate irradiation of small samples. Along with the shutter is a real-time, small-field dosimetry solution that is based on scintillation detectors developed by Medscint, a specialist technology company in Canada.
The plastic material of the scintillation devices enables near-water-equivalence, nanosecond response times and high spatial resolution with MR linac compatibility, as well as robustness that helps protect against radiation damage, according to Physics World
“Plastic scintillation detectors are an ideal dosimeter for ultrahigh-dose-rate radiotherapy. By placing the scintillation detectors in close proximity of the beam shutter, we’ve been able to verify dose delivery and confirm that our system can accurately expose for short pulses down to 1 ms duration,” Magdalena Bazalova-Carter, lead physicist on the project and head of the X-ray Cancer Imaging and Therapy Experimental (XCITE) Lab at the University of Victoria, told the publication.
The detectors have a compact footprint of 0.5 mm long and a 0.5 mm diameter that makes them useful for small-field and multipoint dosimetry. It is optimized to deliver uniform dose on samples that are 6 mm in diameter or less.
The XCITE team is currently using the prototype X-ray tube system on fruit fly larvae and other small animals to track and compare their survival to those irradiated with conventional technologies. The plastic scintillators indicate if the dose is off for any reason and allows it to figure out the reason more easily.
“The early results are promising,” said Alex Hart, a Ph.D. student within the XCITE program. “We’re now looking at the possibility of adding Medscint scintillation detectors to provide real-time, online readout of dose delivery.”