A Polyvinylidene Fluoride 28 nm CMOS Active Ultrasound Sensor for the Experimental Measurement of Proton Beam Range in Hadron Therapy

Pulsed particle beams in hadron therapy treatments generate ionoacoustic signals (10–250 kHz ultrasound) that contain morphological and dosimetric information about the deposited dose, with accuracies superior to traditional nuclear imaging techniques. However, the application of this technique is limited by the immature detector technology that cannot acquire the weak signals (fractions of Pa) of clinical treatments. This letter aims to overcome this limitation by developing the first dedicated active ionoacoustic sensor (AIS), composed of a piezoelectric polyvinylidene fluoride and a dedicated low-noise amplifier in 28 nm complementary metal-oxide semiconductor (CMOS) technology. The AIS prototype is characterized in the electrical and acoustic domains, and its noise and imaging performances allow it to reconstruct the dose deposition of a simulated 200 MeV proton beam with a gamma index 3%/3 mm higher than 95% with a Bragg peak dose as low as 25 mGy.