ESTRO 2024 - Abstract Book

S3230

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Figure 1 Monte-Carlo determined effective dose rates from a FLASH proton beam of 76.4nA nozzle current for key locations in the vicinity of the research vault at the Christie Proton Centre. Error bars are ± one standard deviation of the combined dose rates.

Restrictions were found to be required for a number of locations for specific nozzle currents:

>1.5nA access to the plant room above should be prevented

>5.7nA the research control room complex should be designated as controlled, and special procedures followed to limit exposure

>13nA access to some public areas may need to be restricted depending upon intended beam use

Conclusion:

FLASH survey measurements and Monte-Carlo modelling were successfully used to determine the suitability of shielding at our centre for use with FLASH proton beams. The assessment showed that the shielding was suitable for use with the maximum beam currents currently available, but with three levels of area restrictions required. Monte Carlo calculations using the latest ICRP conversion factors improved accuracy, and reduced the estimated dose rates. The generalised methodology in Figure 2 can be used to assess the suitability of existing shielding for use with FLASH proton beams.