Physical Sciences

Abstract: Radiation fields around collimated or shielded sources exhibit strong gradients whose accurate delineation is critical for worker protection and emergency response. Mobile robots can survey such fields, but they sample sparsely and irregularly along their trajectories, and it remains unclear which reconstruction method can be trusted, and where. Using a single dominant collimated source in a two-dimensional indoor setting, this study shows that the answer depends decisively on sampling geometry, and proposes a physics-guided Gaussian process (GP) that performs reliably under trajectory-constrained sampling. A tracked robot combining light detection and ranging (LiDAR)-based simultaneous localization and mapping (SLAM) with a γ dose-rate detector surveyed a collimated Cs-137 field in seven independent runs, and all methods were evaluated under both random hold-out (interpolation near visited locations) and spatial block cross-validation (extrapolation into unvisited regions), with Poisson-sampled simulations providing truth-referenced comparisons. Under uniform sampling, a multilayer perceptron (MLP) robustly outperformed GP variants (R²=0.95, stable across 18 seed combinations); under trajectory sampling, its advantage vanished at visited locations and reversed catastrophically in unvisited regions. The proposed physics-guided GP, which uses a fitted collimated-beam template as the GP mean with a Matérn 3/2 residual process, achieved the highest extrapolation R² (median 0.61; best baseline 0.31), reduced the extrapolation error by 32–69% relative to all eight baselines, recovered interpretable source parameters, and provided calibrated predictive uncertainty; a runtime fit-quality gate further renders the correctness of the embedded prior an observable quantity, so the method flags when its own assumptions fail. These results offer quantitative guidance for method selection in robotic radiation mapping under the as-low-as-reasonably-achievable (ALARA) principle.

Abstract: Backgroung / Objective: Radiomics offers a powerful, non-invasive approach for extracting quantitative features to predict lesion phenotypes. This study performs a radiomic characterization of breast tissue using synchrotron radiation breast computed tomography (SR-bCT). Method: Four mastectomy samples were imaged at the Australian Synchrotron (ANSTO) using five energies (25, 32, 35, 40, and 60 keV). From 10 slices per energy for each sample, 1546 regions of interest (ROIs) were extracted across four tissue subtypes: fatty, glandular, fibrous, and microcalcified. Using Pyradiomics, 93 features were initially calculated and then reduced to 34, eliminating highly correlated variables to reduce redundancies. Seven linear regression models and a discriminant analysis evaluated subtype tissue separation and radiomic characterization across individuals and combined samples and energies with a good fit (0.81≤ R ≤ 0.98). Results: The study identified 6 robust possible biomarkers independent of sample variability and energy levels, whose mean values are significantly different among the 4 tissue subtypes (clusters, p< 0.001). The selected biomarkers were: 90th Percentile, Kurtosis, Skewness, GLCM IDM, GLDM LDE, and NGTDM Coarseness. These metrics successfully differentiated all tissue pairs (microcalcifications/fat, microcalcifications/gland, microcalcifications/fiber, fat/gland, fat/fiber and gland/fiber), with p < 0.05 inside the most general regression model and p< 0.0001 with the linear discriminant separation in clusters. Conclusion: Findings indicate that some first-order and second-order texture metrics reflecting global dependencies remain stable across experimental conditions. Conversely, fine-texture metrics are highly sensitive to sample energy changes, limiting their generalizability. These results align with successful biomarkers in mammography and validate the potential of radiomics in SR-bCT characterization.

Abstract: Theranostics has transformed nuclear medicine from an imaging-focused discipline into a data-rich radiation medicine platform in which target expression, pharmacokinetics, tumor dose, and response can be measured in the same patient. This evolution is clinically important because radiopharmaceutical therapy (RPT) is increasingly sequenced or combined with external-beam radiotherapy (EBRT) to improve precision, efficacy, and patient outcomes while potentially reducing toxicity. A rigorous combined-modality approach requires patient-specific image quantification, absorbed-dose estimation, spatial registration to the EBRT planning geometry, explicit uncertainty handling, and a clear distinction between physical absorbed dose and biologically meaningful effect. This review summarizes the current theranostic landscape, established and emerging RPT platforms, radiobiologic differences between EBRT and RPT, and practical methods for cumulative patient dose assessment. Liver-directed 90Y radioembolization combined with focal EBRT remains the most developed model, while head and neck, prostate, meningioma, and bone-dominant strategies illustrate how post-therapy imaging and voxel-level dosimetry can guide EBRT adaptation. Across platforms, direct addition of absorbed dose in gray (Gy) is a geometric description, not automatically a biologic endpoint. Future theranostic radiation medicine should therefore be built on prospective trials with prespecified dosimetry and shared cross-modality reporting standards.

Abstract: CH₃NH₃PbBr₃ (MAPbBr₃) single crystals have shown great potential in X/γ-ray detection. However, stable electrodes for MAPbBr₃ single crystals still remains challenging. In this work, multi-layer electrodes including Au, Au/Ti and Au/Pt/Ti are investigated. Through I-V characterization, Au/Pt/Ti shows Ohmic contact behavior and lowest dark current. The potential contact is also confirmed by Kelvin force probe. Based on this low noise electrodes, 59.5 keV monochromatic X-ray photon counting detection and imaging is demonstrated. This work provides useful information for electrodes design in lead halide perovskites-based optoelectronic devices.

Abstract: Fabio Sauli introduced Gas Electron Multiplier (GEM) technology in 1997, which has since evolved into one of the most versatile and widely adopted micro pattern gaseous detector (MPGD) technologies for tracking in High Energy Physics (HEP) experiments. Owing to its high rate-handling capability (∼MHz/mm²), good position resolution (∼100μm), and operational robustness in high radiation environments. GEM detectors have become an indispensable component of modern tracking systems. The heart of a GEM detector is a thin Kapton polyimide foil (∼50μm) clad with copper (∼5μm) on both sides and containing an array of regularly spaced holes (typically diameter of ∼70μm and pitch of ∼140μm) fabricated using photolithographic techniques. The presence of the dielectric substrate (Kapton) within the amplification region introduces a time dependent response when the detector is exposed to external irradiation, a phenomenon commonly referred to as the charging-up effect. This effect arises from the accumulation of charge on the insulating Kapton surfaces, leading to a gradual modification of the local electric field configuration inside the GEM holes and, consequently, a variation in the detector gain over time. The charging-up behaviour has been systematically investigated for triple GEM chamber prototypes using an Fe-55 radioactive source (5.9 keV X-rays). The characteristic charging-up time constant has been extracted, and its dependence on detector gain and irradiation rate has been examined. In addition, the uniformity of detector performance in terms of count rate, gain, and energy resolution has been studied both before and after the charging-up process. In this review article, the experimental setup, data acquisition methodology, and analysis procedures developed and carried out by our group are summarised. The key findings reported by other groups, relevant Monte Carlo simulation efforts, and future outlook for the charging-up investigation on GEM based detectors are also discussed in this article. The investigations and their outcomes reviewed here provide valuable insight into the charging-up dynamics of GEM detectors and their dependence on operational parameters.

Abstract: Balancing accuracy and accessibility in solar energy flux estimation models remains a key challenge in atmospheric radiative transfer research. Since spectral models require computationally intensive spectral calculations, a widely adopted simplification strategy is to parameterize atmospheric spectral transmittances using various wavelength-averaging formulations. This work introduces a broadband parametric model derived from a spectral model that accurately estimates the three components of solar irradiance, direct normal, diffuse, and global under clear-sky conditions. The procedure used to develop the model is structured in two stages. Initially, discrete broadband transmittances are obtained by applying an independent integration scheme to the spectral transmittances provided by the source spectral model. The second stage involves fitting these results to obtain continuous broadband atmospheric transmittances, expressed as analytical functions depending solely on atmospheric state parameters and remaining independent of wavelength. The model development procedure is relatively classical; however, the calculation of the diffuse component introduces a new approach for estimating the fraction of aerosol scattering directedtoward the ground. The model was tested against data collected fromeight radiometric stations distributed across six continents andbenchmarked against two well-established reference models. Overall, theresults indicate a high level of accuracy and demonstrate the practical applicability of the model.

Abstract: X-ray imaging of dense breasts and breast implants often suffers from reduced lesion visibility due to strong attenuation, while conventional rhodium (Rh) K-edge filtering typically suppresses high-energy photons. This study presents a Monte Carlo-based simulation and optimization framework for spectroscopic mammography using a voxelated Cadmium Telluride (CdTe) sensor, enabling quantitative evaluation of energy-dependent image quality. The system accurately simulates sensor fluorescence and inter-voxel energy redistribution, enabling direct comparability with real-world performance. Energy-resolved simulations in the 10-50 keV range were used to compute spectroscopic contrast-to-noise ratio (CNR) curves and identify optimal spectral regions and filter configurations. Replacing the standard Rh filter with aluminum (Al) filtration increased CNR by more than 23% with only a ~5% increase in entrance surface dose (ESD), significantly improving the visibility of hydroxyapatite microcalcifications, even behind dense tissue or implants. The shown work demonstrates practical guidelines and analysis for energy-resolved imaging optimizations obtained from simulations. The results imply that spectroscopic photon-counting detectors and methods can enhance dense-breast mammography image quality while maintaining low patient dose.

Abstract: Spatially fractionated radiotherapy with X ray minibeams (x MBRT) aims to increase normal tissue tolerance by delivering alternating high and low dose regions. We provide a Monte Carlo–based framework to design and optimize multislit collimators, quantifying how geometry and material govern peak–valley modulation. A validated digital twin of the SmART X RAD225Cx irradiator was implemented in TOPAS/Geant4. Various x-MBRT collimators were simulated with parallel or divergent slits. The parameter space covered slit width w (0.1–0.9 mm), center to center spacing CTC (1–3 mm), thickness T (1–5 mm), and acceptance angle θ. Dose was scored in a 2 × 2 × 2 cm³ water phantom at 1 cm depth. The valley dose increased linearly with the filling factor (w/CTC) and as ~T². For fixed w/CTC, PVDR increases with larger CTC via an increase of peak dose, with valley dose nearly constant. Peak transmission saturated at θ ≈ 3°, indicating minimal benefit from larger acceptance. Divergent slits yielded flatter lateral profiles but higher valley doses than parallel slits, reducing PVDR around the central axis. This Monte Carlo study provides insights for optimizing collimator geometries in x-MBRT using small-animal irradiators, informing the design of more effective collimation systems to enhance treatment precision and normal tissue sparing.

Abstract: Customer-grade affordable active radon monitors occupy a growing segment of the radon measurement market. This is no surprise given the fair price, easy operation, versatile applicability and reasonable performance. A relatively recent member of the family is the Aranet Radon-plus, made by a Latvian company. Two devices were tested in parallel together with one RadonEye, an already well established monitor of this class. In comparison with the latter, the Aranet has a somewhat lower sensitivity, but additional useful features, namely a time stamp and measurement of meteorological parameters. Operability via Smartphone and Bluetooth is very similar. One difficult issue is data smoothing that introduces artificial autocorrelation of reported data which is problematic in certain applications. In this paper, several experiments under different exposure scenarios (indoors, outdoors, thoron, moving) to assess the performance of the Aranet and some considerations regarding counting statistics are presented.

Abstract: The implementation of FLASH Radiotherapy (FRT), characterized by ultra-high dose rates (UHDRs) frequently exceeding 106 Gy/s in microsecond pulses, imposes stringent requirements on real-time dosimetry. Conventional ionization chambers suffer severe ion recombination and space-charge limitations under these conditions. This review summarizes the state of SSD technologies—including conventional standard silicon diodes, advanced SiC diodes, LGADs, and pixel detectors—and compares their performance, linearity, and dynamic range in UHDR environments. Particular attention is devoted to operational modes (integrating vs. counting), saturation mechanisms, and readout electronics, which frequently dominate detector behavior at FLASH conditions. We discuss experimental results from recent UHDR beamlines and highlight emerging concepts that will shape future clinical translation.

Abstract: Ionizing radiation affects enzymes, which are critical for most cellular functions, by inducing chemical alterations in their molecular structures, often resulting in the inhibition of their activities. Understanding the molecular and kinetic mechanisms underlying these effects requires suitable experimental protocols and models tailored to specific enzymes and their substrates. In this study, we present a convenient experimental approach utilizing a medical linear accelerator (LINAC) suite as a precise means for irradiating enzyme solutions. Additionally, we examine the effects of ionizing radiation on the catalytic activities and potential structural changes of two enzymes: invertase (β-fructofuranosidase) and collagenase.

Abstract: Boron Neutron Capture Therapy (BNCT) is a radiotherapeutic modality which couples selective pharmacological delivery of 10B with irradiation by low-energy neutrons to achieve highly localized tumor cell killing. The BNCT therapeutic approach is undergoing rapid evolution driven primarily by advances in compact accelerator-driven neutron-source and associated facility-level nuclear infrastructure. This review examines the key physical and radiobiological principles of BNCT, with emphasis on the current engineering and operational aspects, such as neutron production and moderation, spectral shaping, beam optimization and dosimetric quantification, that critically influence clinical translation. Recent progress in 10B production and enrichment, as well as in strategies for efficient 10B delivery, is also briefly addressed. By tracing the pathway from neutron source to clinical target, the review defines the state of the art in BNCT technology , identifies the main physical and infrastructural challenges and delineates the multidisciplinary advances needed to support widespread clinical implementation of next-generation BNCT systems.

Abstract: A catalog of values of predicted energies of the K-XRF escape-peaks from compounds, used for radiation detectors, is presented for given incident gamma-rays suited for nuclear molecular medicine and low-energy spectrometry. The information relating to the compounds adds to that relating to the individual natural elements recently posted [RSC2025a]. The results of powerfunctions best-fit of XRF energy values vs. Z are listed in Table 1 for Kα2 orbital and Kedge. These expressions, allow simple calculations, avoiding the development of complex software. An extensive literature survey has been carried out mainly considering text-books, review articles and research reports. A final number compounds (Nc) equal to 729 has been obtained, whose distribution per number of constituting elements (Ne) is reported in Table 2. The predicted energy peaks are arranged in Tables 3 to 7 per Ne in the range from 2 to 8, showing the average value of 3.92 elements per compound. The catalog is conceived for nuclear molecular medicine and gamma-ray spectrometry where such peaks need to be recognized and their underlying area known in order to allow quantitative information.

Abstract: Conventional melanoma cancer treatments, including surgery, radiotherapy, and chemotherapy, are often costly and associated with adverse effects such as tissue damage, pigmentation changes, pain, inflammation, and prolonged recovery. Hence, this study explores photodynamic therapy (PDT) using copper-cysteamine nanoparticles (Cu-Cy NPs) combined with UVA irradiation as a potential approach to enhance therapeutic efficacy while reducing side effects. A375 melanoma cells were treated with Cu-Cy NPs (3 μg/mL) and exposed to UVA light for 2 or 10 minutes. Cell viability, ROS generation, and apoptosis were evaluated using MTT, NBT, and flow cytometry assays, respectively. Neither Cu-Cy NPs nor UVA irradiation alone significantly increased ROS or apoptosis. However, their combination for 10 minutes synergistically elevated ROS levels and induced pronounced apoptosis, with cell death comparable to cisplatin-treated positive controls. Shorter UVA exposure (2 minutes) did not produce a significant effect, indicating the critical role of irradiation duration. Comparative analysis across cell lines confirmed that A375 cells exhibit high sensitivity to UVA-mediated PDT, highlighting cell-line-specific differences in response. The combination of UVA irradiation and Cu-Cy NPs effectively induces apoptosis in melanoma cells, highlighting a synergistic effect that surpasses individual treatments. This approach represents a potential alternative or adjunct to conventional therapies, with the advantage of minimizing adverse effects.

Abstract: A catalog of K-XRF escape-peak energy from natural elements and for several energies of gamma-rays incident on a single-element detector is presented. The parameters of a power-model are listed In Table I for predicting the energy of such peaks.In Table II predicted peaks are arranged in order of increasing atomic number (ranging from 4 to 92) of the detector component and for the Kα2 XRF main emission.This catalog is conceived for nuclear medicine and gamma-ray spectrometry where such peak need to be recognized and known as underlying area in order to gain advantage of quantitative analysis, but, also for detector-developers as well as for spectroscopists that should be interested in the issue.

Abstract: During the last two decades relevant progress has been achieved in silicon photomultiplier (SiPM) technology, so that in an increasing number of radiation detection applications they are proposed as a viable alternative to traditional photomultiplier tubes (PMT). Applications where the light from tiny scintillating crystals is detected by a single SiPM raise the question of the possible non-linearity of the response due to saturation of the number of microcells involved. In other cases where larger scintillators subtend arrays of SiPMs the same question could hold. This work tries to disentangle such a question with a realistic numerical approach and a few tests, showing that possible saturation effects depend on the interplay between the features of the scintillator and of the SiPM (array). The quantitative results of this analysis can likely be used to better plan future radiation detection systems and to highlight their linearity boundaries.

Abstract: Dosimetric analysis is a critical component in radiation therapy delivery. In radiation therapy, bolus materials are frequently used to alter the dose distribution. In this study, we used Optically Stimulated Luminescent Dosimeters (OSLDs) to carry out a thorough dosimetric examination of several bolus materials when used with high-energy photon beams. Our research aimed to assess the performance of various bolus materials in terms of dose enhancement and surface dose. The findings of this study offer important insights into choosing the best bolus material for a particular clinical situation, optimizing treatment outcomes, and ensuring proper patient care.

Abstract: Fast-charged particles have been used in diagnosis and treatment since the 19th century. Positrons are widely used in medical imaging through positron emission tomography, but their therapeutic potential remains underexplored due to technology limitations associated with the lack of research on their effectiveness against cancer. One way to understand their behavior is by calculating absorbed dose distributions in tissue, which can be safely and realistically done using computational simulations such as the Monte Carlo Method. This study investigates the interaction of a positron beam with brain tissue and also with a tumor within it, through simulations using the TOPAS software. Depth dose profiles and absolute absorbed dose values were obtained in the range of 6-24 MeV. Validation was performed using data from the water phantom with electron beams. The results showed that, at certain depths in brain tissue, the absorbed dose by positrons was higher than that of electrons under the same conditions—ranging from 57% to 463% more. These findings suggest that positrons may offer advantages over conventional electron therapy and contribute to the development of novel therapeutic approaches.

Abstract: Synchrotron radiation light source has been successfully used in material science, biomedicine, and other fields because of its high intensity, good monochromaticity, and excellent coherence and collimation. In recent years, the source has significantly expedited the advancement of medical applications. High contrast and spatial-temporal resolution images based on synchrotron radiation X-ray have been obtained, presenting innovative opportunities for precise clinical diagnosis and therapy. In this review, we first delineate the characteristics of synchrotron radiation beamlines, then conclude recent breakthroughs in synchrotron X-ray imaging and radiotherapy for various clinical applications, particularly for heart, breast, lung, bone, and brain conditions. Novel synchrotron radiation X-ray radiotherapy treatments, including microbeam and stereotactic radiotherapy, have shown great potential for clinical application by enabling more precise and low-dose treatments. Synchronized radiation techniques are projected to redefine diagnostic criteria for imaging and therapeutic options for resistant cancer, offering immense potential for medical applications.

Abstract: Blood concentrations of essential trace elements can be used to diagnose conditions and diseases associated with excess or deficiency of these elements. Inductively coupled plasma mass spectrometry (ICP-MS) has been employed for such measurements, but maintenance and operation costs are high. XRF detectability in cutaneous blood of iron (Fe), copper (Cu), zinc (Zn), and selenium (Se) was assessed as alternative to ICP-MS. Three phantoms were made up of two polyoxymethylene (POM) plastic cylindrical cups of 0.6-mm and 1.0-mm thick walls and a 5.3-mm diameter POM cylindrical insert. Six water solutions of Fe in 0 to 500 mg/L and Cu, Zn, and Se in 0 to 50 mg/L concentrations, were poured into the phantoms to simulate x-ray attenuation of skin. Measurements using an integrated x-ray tube and polycapillary x-ray lens unit generated 24 calibration lines. Detection limit intervals in mg/L were: (36, 100), (14, 40), (3.7, 10), and (2.1, 3.4) for Fe, Cu, Zn, and Se, respectively. Fe was the only element with detection limits lower than its 480 mg/L median human blood concentration. Estimated radiation dose and equivalent dose to skin were below those of common radiological procedures. Applications will require further instrumental development, and finding a calibration method.