Particle therapy and FLASH radiotherapy offer promising advancements in cancer treatment. However, accurately measuring radiation dose within the body, especially in real-time and high dose rates characteristic of FLASH radiotherapy, poses significant technological challenges. Ionoacoustic methodologies offer an innovative and non-invasive approach to particle therapy dosimetry, leveraging the generation of acoustic waves from energetic particle interactions. As the initial pressure distribution of a ionoacoustic wave is linearly proportional to the absorbed dose, it is possible to reconstruct the dose distribution from the acoustic signals. This work explores the viability of ionoacoustic dosimetry through computational simulations of 9 MeV FLASH electron beams using the k-Wave toolbox in MATLAB with a variable number of sensors with the goal of maximizing the gamma index with a 1%/1 mm standard. Two different imaging algorithms were compared, and the results clearly indicate that interpolated time reversal (ITR) outperforms standard time reversal (STR) across virtually all sensor configurations. Remarkably, ITR achieves high-quality image reconstruction with a significantly lower number of sensors. For instance, using ITR acceptable images (above 90% of the gamma index less than 1) were produced with as few as 24 sensors, 78% less than the ones necessary for STR, which required at least 108 sensors to reach a similar accuracy of 90.75%. When using 108 sensors, ITR demonstrated a 99.80% accuracy, representing an improvement of 46.25 times over STR.

This paper presents a continuous time voltage amplifier based on a classical MOS Transistor (MOST) input differential stage feeding a regulated cascode output stage. One of the most interesting aspects of the presented circuit is the introduction of complex conjugated poles in the output stage which together with a simple R-C network at the input of the differential stage allows to synthesize a 3rd-order low-pass Butterworth transfer function at 20 dB of passband gain. The proposed circuital technique has been validated by the design of a 3rd-order low-pass filter and amplifier in 28 nm CMOS technology. The proposed circuit has 5.2 nV/√Hz in-band Input Referred Noise (IRN) Power Spectral Density (PSD), −3.2 dBm Input 3rd-order Intercept Point (IIP3) at 20 dB passband gain and a final Signal-to-Noise-Ratio (SNR) of 60 dB. This solution is particularly efficient in terms of both power consumption and linearity while performing large SNR, as demonstrated by the final Figure-of-Merit of 159.2 dBJ−1.

This paper presents the design and experimental characterization of a Proton Sound Detector (ProSD), a device that physically captures and senses the weak acoustic signal emitted by the fast energy deposition at the end of the same proton beam range. The measured acoustic signal Time-of-Flight provides a very accurate (13 μm accuracy) measure of the proton beam penetration depth in water, improving the proton range verification accuracy w.r.t. previous works in pre-clinical scenarios. This suggests interesting possibilities for high-accuracy and real-time beam monitoring and calibration in hadron-therapy for cancer treatment. The detector has been fully characterized and tested with a physical 20 MeV proton beam in a water energy absorber. The ProSD and the water tank have been mounted in front of the exit layer of a 20 MeV 120 ns pulse time-width proton beam. A clear sinusoidal-like acoustic signal of 5 Pa and 2.3 MHz frequency has been detected at 12 dB SNR with 0.8 Gy single shot dose. After averaging 10 beam shots the achieved Signal-to-Noise-Ratio is 22 dB allowing a ±7.5 μm precision vs. previously reported ±45μm ionoacoustic precision.