The increasing interest in hadron therapy has heightened the need for accurate and reliable methods to assess radiation quality and the biological effectiveness of particles used in treatment. Microdosimetry has emerged as a key tool for this, demonstrating its potential, reliability, and suitability. In this context, solid-state microdosimeters offer technological advantages over traditional Tissue-Equivalent Proportional Counters, and recent advancements have further improved their performance and reliability. However, one critical challenge in solid-state microdosimetry is the so-called 'border effect', which can impact measurement accuracy. In this study, the border effect in diamond microdosimeters was thoroughly studied using Ion Beam Induced Charge (IBIC) analysis. The research, relying on experiments conducted at the Surrey Ion Beam Centre, developed an effective method to characterise and quantify the border effect. Geant4 Monte Carlo simulations were also employed to assess the impact of the border effect under typical proton therapy conditions, with a specific model developed and validated to reproduce this effect in simulations. Results showed potential significant variations of up to 40% in ȳ_F and 20% in ȳ_D values, highlighting the importance of accurately characterising the border effect and encouraging further research to mitigate its influence on microdosimetry measurements.

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.

Objective. This work presents the first experimental characterization of the DIODE detector, a novel detection system based on single-crystal diamond, designed for simultaneous dosimetric and microdosimetric measurements in clinical proton therapy. The aim is to evaluate its capability to measure absorbed dose, and estimate LET and RBE variations along a clinical proton beam. Approach. The detector was tested under a 70 MeV monoenergetic proton beam at the Trento Proton Therapy Centre. Depth-dose and lateral profiles were compared with EBT3 radiochromic films. Microdosimetric spectra were simultaneously acquired and benchmarked against a mini tissue-equivalent proportional counter (TEPC). Monte Carlo (MC) simulations were also performed to model the experimental setup and the DIODE geometry. Main results. The detector showed linearity with dose with a sensitivity of 0.60 ± 0.01 nC Gy⁻¹, with a dark current below 0.1 pA, ensuring a good signal-to-noise ratio. Depth-dose profiles matched EBT3 film data and MC simulations, with differences below 2% in peak-to-plateau ratios, indicating limited LET dependence. The dose-mean lineal energy y ¯ D closely agrees with simulated dose-averaged LET values, except in the beam entrance region. In this area, y ¯ D values were lower than those obtained with the mini-TEPC due to electronic saturation limiting the detection of rare high-LET secondary fragments. Variation in RBE was assessed from the microdosimetric data, based on Loncol’s weighting function, which refers to clonogenic cell survival. RBE values ranged from ∼1.1 at the entrance to ∼1.8 in the distal region, consistent with mini-TEPC data and literature RBE₁₀ values for V79 and U89 cells. Lateral dose and microdosimetric profiles confirmed high spatial resolution and revealed proton energy variations near the Bragg peak. Significance. The DIODE detector demonstrated reliable performance for simultaneous dosimetric and microdosimetric characterization of clinical proton beams. Its ability to measure dose, and to support LET and RBE assessment through microdosimetric modelling, in a single device, highlights its potential as an advanced tool for beam quality assessment and biologically optimized treatment planning in proton therapy.

The creation of innovative systems that are able to combine diagnosis and therapy is a crucial opportunity in nuclear medicine. Here, we propose a methodological and multiscale approach for the development of a theranostic platform based on AuNRs functionalized with radiopharmaceuticals. AuNRs offer a versatile and effective system due to their unique physicochemical properties and the possibility of surface functionalization with targeting molecules. Within this framework, key challenges include the functionalization of AuNRs to target the cell nucleus, the loading of AuNRs with radiopharmaceuticals, and the investigation of Auger electron emission from AuNRs under gamma irradiation. Multiscale modelling is employed to describe the behaviour of the system within the cellular environment and to predict potential radiobiological enhancement effects, including synergistic interactions between functionalized AuNRs and radiopharmaceutical agents such as ^99mTc-sestaMIBI. The experimental activity includes gamma irradiation studies, along with the structural and physical characterization of nanomaterials and in vitro biological investigations on T98G cells, to evaluate cytotoxicity and metabolic alterations, with the aim of assessing the potential synergistic effects of the combined system.