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.

Abstract: This study proposes an innovative methodology that combines experimental microCT imaging with Monte Carlo irradiation simulations using the PENELOPE code aimed at enabling detailed analyses of different features involved in the irradiation processes along with elemental mapping, as required for X-ray fluorescence imaging of in vivo samples. By examining the relationship between signal-to-noise ratio (SNR) and absorbed dose (D), a mathematical approach was proposed to determine critical points where their rates of change are equal. Thus, allowing to identify optimal concentrations of gold dispersions to the specific simulated system of interest, where the signal quality efficiently improves as weighted in relation to the absorbed dose. The proposed methodology has been applied to a typical small animal (rat) microCT that was further used by the computationally implemented model to infuse the animal kidneys by different amounts of gold. For the K_(α_1 ), K_(α_2 ), and K_(β_1 ) lines, these critical concentrations were found to be 0.78 %, 1.32 %, and 0.32 % w/w, respectively, while no such behavior was identified for the K_(β_2 ) line under the given configuration considered as a representative/typical small animal infused with Au-based agents. The obtained results highlight the methodology's ability to optimize the balance between the absorbed dose and corresponding SNR, obtaining high-quality images without compromising in vivo samples due to excessive radiation exposure. Moreover, the proposed methodology provides high-resolution structural imaging and detailed elemental mapping, facilitating the analysis of detection limits along with the overall system performance. These findings confirm the robustness and reliability of the approach, offering a valuable tool for refining X-ray spectroscopy imaging processes and advancing X-ray fluorescence-based tomography techniques.

Abstract: Diagnostic Reference Levels (DRL) in digital mammography were determined from 31,040 digital mammography images acquired from diagnostic and screening examination data from eight state-managed mammography centres/units in the Republic of North Macedonia (RM). The main objective is to establish a Diagnostic Reference Level for mammography examinations at different ranges of breast thickness. Materials and methods: ~30,000 mammography images were used to evaluate Mean Glandular Dose (MGD), and Compressed Breast Thickness (CBT)for each projection, craniocaudal (CC) and mediolateral oblique (MLO). The stratified DRL was derived by calculating the 75th percentile of the MGD across all the samples at various CBT ranges for both projections. Results and Discussion: The overall median MGDs, minimum, and maximum were calculated to be 1.15 mGy, 0.1 mGy, and 9.93 mGy, respectively. As the CBT increased from 7 to 120 mm, the 75th percentile of the MGD increased from 0.94 mGy to 3.67 mGy for CC, and from 0.44 mGy to 4.91 mGy for MLO projections. Conclusion: The study established local DRLs for the digital mammography systems at the 75th percentile, which compared well with the values reported by other countries/regions. The DRL defined per CC and MLO image view for a specific CBT indicated that at least one mammography facility needs optimization.

Abstract:

In this work, a first trial of a method has been developed to estimate the average annual indoor radon activity concentration from three-week short-term measurements using active radon-222 measuring devices, considering relevant influencing parameters. 24 long-term measurements (6 months) and 50 short-term measurements (3 weeks) were carried out in 24 indoor spaces in private houses in four Austrian federal states between October 2022 and July 2023. At the same time as the short-term measurements, ambient parameters (outside and inside temperature, air pressure inside, outside, air humidity inside, outside, wind speed, wind direction, amount of precipitation) were also recorded to investigate their influence on the measured radon-222 activity concentrations. Building and usage data of the indoor spaces examined were also collected. Based on the evaluation of the radon-222 measurements carried out, a first guideline was developed for estimating the annual mean value of the radon-222 activity concentration from short-term measurements lasting around three weeks. Using further measurements and advanced physical-statistical methods, it would be possible to test, validate and improve the generalization of the method to indoor spaces and to further improve the functional relationships.

Abstract: The interest in Boron Neutron Capture Therapy (BNCT) has been recently increasing thanks to the latest advancements in accelerator technology which allow to generate the required neutron field from accelerator facilities that could be hosted in hospitals or clinical centres. BNCT is a form of radiation therapy which relies on the highly localised and enhanced biological effects of the boron-10 (B-10) neutron capture (BNC) reaction products to selectively kill cancer cells. The BNC products are low-energy alpha and lithium ions, which are characterised by a high Linear Energy Transfer (LET) and a very short range lower than 9?m. The energy deposition and interaction with critical biological target such as DNA molecules is therefore strongly dependent on the B-10 spatial micro-distribution into the cells. In this framework, the Fluorescent Nuclear Track Detectors (FNTD) could be a promising device for the visualisation of the ion traversals induced in BNCT. FNTD consists of a fluorescent single-crystal aluminium oxide doped with carbon and magnesium, coupled with a Confocal Laser Scanning Microscopy (CLSM) read-out. Its biocompatibility allows to deposit and grow cells samples on its surface. If a layer of borated cells is deposited and irradiated by a neutron field, the energy deposited by the BNC products and their trajectories can be measured by analysing the corresponding track spots induced at different depths of the detector. This allows to reconstruct the position where the measured particles were generated, hence the micro-distribution of B-10. A FNTD was tested in three irradiation conditions to study the feasibility of FNTD for BNCT applications. The device was firstly irradiated by the alpha particles emitted by an Am-241 source (with energy of about 5.5 MeV). The same radiation field moderated by a 23?m layer of Mylar was then used to obtain alpha particles with a lower energy of about 2.5 MeV, thus closer to BNC products. Finally, the FNTD was tested at the University of Pavia’s LENA (Applied Nuclear Energy Laboratory) under a thermal neutron beam. A standard reference material (SRM) consisting of boron implanted on a silicon wafer was placed on the detector surface to reproduce a typical BNCT radiation field. The FNTD allowed to successfully measure the correct alpha particles range and mean penetration depth expected for all the radiation fields employed. This work proved the feasibility of FNTD to reconstruct the tracks of the alpha particles produced in typical BNCT conditions. Hence, FNTD will allow to measure the intra-cellular micro-distribution of B-10, bringing a significant contribution to the advancement of BNCT research. With this purpose, further experiments at LENA irradiating borated cell samples are planned.

Abstract: The image quality index for whole-body bone scintigraphy has traditionally relied on the total count (Total-C) with a threshold of ≥1.5 mc. However, Total-C measurements are susceptible to variability owing to urine retention. This study aimed to develop a skeletal count (Skel-C)-based index, focusing exclusively on bone regions, to improve the accuracy of image analysis in bone scintigraphy. All cases included herein were Total-C≥1.5 mc. Thresholds were set for Skel-C (0.9–1.2 mc) and Total-C (1.75–2.25 mc); patients were grouped according to whether they were above or below these thresholds. The group including all cases was defined as the Total-C 1.5 high group. Sensitivity and specificity were calculated for each group, and receiver operating characteristic analyses and statistical evaluations were conducted. The specificity of the Skel-C < 0.9 mc group was significantly lower than that of the Skel-C ≥ 0.9 mc group and the Total-C 1.5 high group. These findings highlight the importance of achieving Skel-C ≥ 0.9 mc and suggest that Total-C alone is insufficient for reliable image assessment.

Abstract: Effective dose calculation is essential for optimizing Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment plans. Modern GK systems allow independent sector activation, enabling complex dose distributions per shot. This study presents a dose approximation method designed to account for shot flexibility and generate 3D dose external to GammaPlan. A treatment plan was created with the TMR10 calculation for individual sector activations using a Radiosurgery Head Phantom. The resulting dose arrays established a basis set of sector-specific distributions, which were then refer-enced by shot parameters from the plan, allowing dose accumulation through superposition. This superposition approximation (SA) was compared to the original TMR10 using Dice Similarity Co-efficient (DSC), 95% Hausdorff Distance (HD95), and GK deliverability metrics: coverage, selec-tivity, and gradient index, across an isodose normalization range from 10% to 90%. In a cohort of 30 patients with 71 targets, strong agreement was observed between TMR10 and SA in the clinically used 50-60% isodose range, with DSC above 85% and HD95 under 2.18mm. Average differences for coverage, selectivity, and gradient index were 0.014, 0.008, and 0.118, respectively. This method accurately approximates TMR10 calculations within clinically relevant ranges, offering an external tool to assess 3D dose distributions for GK treatment plans.