A Diamond-Based Dose-Per-Pulse X-ray Detector for Radiation Therapy

One of the goals of modern dynamic radiotherapy treatments is to deliver high-dosevalues in the shortest irradiation time possible. In such a context, fast X-ray detectors and reliablefront-end readout electronics for beam diagnostics are crucial to meet the necessary quality assurancerequirements of care plans. This work describes a diamond-based detection system able to acquire andprocess the dose delivered by every single pulse sourced by a linear accelerator (LINAC) generating6-MV X-ray beams. The proposed system is able to measure the intensity of X-ray pulses in a limitedintegration period around each pulse, thus reducing the inaccuracy induced by unnecessarily longacquisition times. Detector sensitivity under 6-MV X-photons in the 0.1-10 Gy dose range wasmeasured to be 302.2 nC/Gy at a bias voltage of 10 V. Pulse-by-pulse measurements returned acharge-per-pulse value of 84.68 pC, in excellent agreement with the value estimated (but not directlymeasured) with a commercial electrometer operating in a continuous integration mode. Significantly,by intrinsically holding the acquired signal, the proposed system enables signal processing evenin the millisecond period between two consecutive pulses, thus allowing for effective real-timedose-per-pulse monitoring.