Development of a compact and portable diamond-based detection system for dosimetry and microdosimetry in ion beam therapy

Ion beam therapy techniques have advanced significantly in the past two decades. However, the development of dosimetric verification methods has lagged. Traditional dosimetry, which offers a macroscopic view of the absorbed dose, fails to address the micrometric-scale stochastic effects crucial for understanding biological responses. To bridge this gap, microdosimeters are used to assess physical quantities correlated with radiation effects. This work reports on the design and testing of a novel detection system based on synthetic single crystal diamond. The system is capable of simultaneously performing dosimetric and microdosimetric characterizations of clinical ion beams. The detector incorporates two active components configured as diamond Schottky diodes, both integrated on a single crystal diamond substrate. In particular, one very small element (sensitive area 0.0078 mm2) was designed to evaluate microdosimetric metrics, while the other large one (sensitive area 4.2 mm2) was designed to measure the absorbed dose to water. Diamond detectors were characterized using the ion beam induced charge (IBIC) technique, employing a 1 MeV protons microbeam. The IBIC map of the diamond detector shows two distinct sensitive areas with quite uniform sensitivity, well contained within the metallic contact regions. Dedicated front-end electronic circuits were designed and implemented for both the dosimetric and microdosimetric signals. These circuits, along with the integrated diamond detector, were embedded in an aluminum waterproof housing to minimize electronic interference. This configuration enables a compact, portable setup compatible with water phantoms. Laboratory tests with alpha particles yielded promising results, demonstrating stable and reproducible responses with a good signal-to-noise ratio.