Advancing GaN detectors toward proton therapy applications

Proton therapy offers highly localized dose delivery for cancer treatment, but its clinical precision critically depends on accurate beam monitoring and patient imaging. Conventional detector technologies remain constrained by limited spatial resolution, dynamic range, and radiation tolerance. Here we demonstrate gallium nitride (GaN) diode arrays as a new platform for proton imaging. Using a one-dimensional GaN array, we image a 65 MeV clinical proton beam with linear response across three orders of magnitude, high sensitivity down to 10 pA, and robustness under irradiation up to 100 kGy. 2D profiles are reconstructed through transverse mechanical scanning with uncertainties in the beam position and linewidth as low as ± 0.07 mm and ± 0.14 mm, respectively. The intrinsic radiation hardness of GaN was experimentally confirmed, while key requirements for 65 MeV proton beam quality assurance and patient radiography were addressed. This proof of concept establishes the foundations for extending the approach to 2D detector matrices, combining high-resolution and real-time imaging.