Implementation and validation of a beam-current transformer on a medical pulsed electron beam LINAC for FLASH-RT beam monitoring

Purpose To implement and validate a beam current transformer as a passive monitoring device on a pulsed electron beam medical linear accelerator (LINAC) for ultra-high dose rate (UHDR) irradiations in the operational range of at least 3 Gy to improve dosimetric procedures currently in use for FLASH radiotherapy (FLASH-RT) studies. Methods Two beam current transformers (BCTs) were placed at the exit of a medical LINAC capable of UHDR irradiations. The BCTs were validated as monitoring devices by verifying beam parameters consistency between nominal values and measured values, determining the relationship between the charge measured and the absorbed dose, and checking the short- and long-term stability of the charge-absorbed dose ratio. Results The beam parameters measured by the BCTs coincide with the nominal values. The charge-dose relationship was found to be linear and independent of pulse width and frequency. Short- and long-term stabilities were measured to be within acceptable limits. Conclusions The BCTs were implemented and validated on a pulsed electron beam medical LINAC, thus improving current dosimetric procedures and allowing for a more complete analysis of beam characteristics. BCTs were shown to be a valid method for beam monitoring for UHDR (and therefore FLASH) experiments.

Automated summary

The study aimed to implement and validate a beam current transformer as a passive monitoring device on a medical LINAC for UHDR irradiations. Results showed that the device accurately monitored beam parameters, exhibited a linear charge-dose relationship, and demonstrated good stability for both short- and long-term measurements.