ESTRO 2024 - Abstract Book

S4742

Physics - Quality assurance and auditing

ESTRO 2024

Measurements in water were performed with a BluePhysics model 10 scintillation detector and PTW's BEAMSCAN MR water phantom on an Elekta Unity 7 FFF energy accelerator. The detector operates at different capacities and integration times. Specifically the measurements were performed with 10 µF capacitance and 700 µs, so the detector is able to measure and plot the emitted signal even between radiation pulses. In a linear accelerator the RF modulator feeds the magnetron with 47 KV and 120 A pulses.

Results:

The figure shows the envelope curve of the pulses measured by the detector before, during and after the Elekta engineer's adjustment. Specifically, the envelope curve of the pulses in initial situation (a), overtrigger detection (b), after adjustment (c) and detail of the accelerator pulses (d). It can be seen how the behavior of the accelerator with respect to the magnetron input current returns to the initial situation.

Conclusion:

The increase of current intensity in the magnetron could eventually lead to a shortening of the magnetron's useful life or to a possible failure, so it is advisable to take measurements with a detector capable of displaying the pulses on the screen and to be able to act before a failure of the equipment occurs. The ability to visualize the pulses with the BluePhysics scintillation detector has proved useful to detect in the process of other measurements a change in the behavior of the accelerator, and correct in this case the calibration of the modulator pulse, prior to a possible failure.

Keywords: MR-linac, scintillator, FMEA

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