English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Recently, shoot-through proton FLASH has been proposed where the highestenergy is extracted from the cyclotron to maximize the dose rate (DR). Eventhough our proton pencil beam scanning system can deliver 250 MeV (the highestenergy), it is not typical to use 250 MeV protons for routine clinicaltreatments and as such 250 MeV may not have been characterized in thecommissioning. In this study, we aim to characterize 250 MeV protons fromVarian ProBeam system for FLASH RT as well as assess the ability of clinicalmonitoring ionization chamber (MIC) for FLASH-readiness. We measured dataneeded for beam commissioning: integral depth dose (IDD) curve, spot sigma, andabsolute dose calibration. To evaluate MIC, we measured output as a function ofbeam current. To characterize a 250 MeV FLASH beam, we measured: (1) centralaxis DR as a function of current and spot spacing and arrangement, (2) for afixed spot spacing, the maximum field size that still achieves FLASH DR (i.e.,> 40 Gy/s), (3) DR reproducibility. All FLASH DR measurements were performedusing ion chamber for the absolute dose and irradiation times were obtainedfrom log files. We verified dose measurements using EBT-XD films andirradiation times using a fast, pixelated spectral detector. R90 and R80 fromIDD were 37.58 and 37.69 cm, and spot sigma at isocenter were {\sigma}x=3.336and {\sigma}y=3.332 mm, respectively. The absolute dose output was measured as0.377 GyE*mm2/MU for the commissioning conditions. Output was stable for beamcurrents up to 15 nA, and it gradually increased to 12-fold for 115 nA. DRdepended on beam current, spot spacing and arrangement and could be reproducedwithin 4.2% variations. Even though FLASH was achieved and the largest fieldsize that delivers FLASH DR was determined as 35x35 mm2, current MIC has DRdependence and users should measure DR each time for their FLASH applications.

Characterization of 250 MeV protons from Varian ProBeam pencil beam scanning system for FLASH radiation therapy