Background and objective: Toenail is an advantageous biomarker to assess exposure to metals such as manganese and mercury. Toenail Mn and Hg are in general analyzed by chemical methods such as inductively coupled plasma mass spectrometry and atomic absorption spectrophotometry. In this project, a practical and convenient technology—portable X-ray florescence (XRF)—is studied for the noninvasive in vivo quantification of manganese and mercury in toenail. Material and methods: The portable XRF method has advantages in that it does not require toenail clipping and it can be done in 3 min, which will greatly benefit human studies involving the assessment of manganese and mercury exposures. This study mainly focused on the methodology development and validation which includes spectral analysis, system calibration, the effect of toenail thickness, and the detection limit of the system. Manganese- and mercury-doped toenail phantoms were made. Calibration lines were established for these measurements. Results: The results show that the detection limit for manganese is 3.65 μg/g (ppm) and for mercury is 0.55 μg/g (ppm) using 1 mm thick nail phantoms with 10 mm soft tissue underneath. Discussion and conclusion: We conclude that portable XRF is a valuable and sensitive technology to quantify toenail manganese and mercury in vivo.

Objective : This study presents the development of a noninvasive method for monitoring Na in human bone. Many diseases, such as hypertension and osteoporosis, are closely associated with sodium (Na) retention in the human body. Na retention is generally evaluated by calculating the difference between dietary intake and excretion. There is currently no method to directly quantify Na retained in the body. Bone is a storage for many elements, including Na, which renders bone Na an ideal biomarker to study Na metabolism and retention. Approach : A customized compact deuterium–deuterium (DD) neutron generator was used to produce neutrons for in vivo neutron activation analysis (IVNAA), with a moderator/reflector/shielding assembly optimized for human hand irradiation in order to maximize the thermal neutron flux inside the irradiation cave and to limit radiation exposure to the hand and the whole body. Main results : The experimental results show that the system is able to detect sodium levels in the bone as low as 16 µ g Na g ⁻¹ dry bone with an effective dose to the body of about 27 µ Sv. The simulation results agree with the numbers estimated from the experiment. Significance : This is expected to be a feasible method for measuring the change of Na in bone. The low detection limit indicates this will be a useful system to study the association between Na retention and related diseases.

Proton FLASH radiotherapy represents a promising innovation in the treatment of abdominal cancers, offering the potential to expand the therapeutic window by delivering ultra-high dose rates (UHDR) that spare normal tissue while maintaining tumor control. This approach is particularly beneficial for gastrointestinal (GI) tumors, where radiation dose escalation is often limited by the radiosensitivity of nearby organs. This review explores recent preclinical, planning, and technical developments in proton FLASH for abdominal sites and outlines the challenges and future directions for clinical translation. We reviewed the available published literature on proton FLASH radiotherapy, with a focus on abdominal applications. Recent preclinical studies in abdominal models have shown encouraging, though inconsistent, evidence of reduced toxicity with proton FLASH. Parallel advances in treatment planning have also demonstrated technical feasibility in achieving UHDR across complex abdominal geometries. However, key challenges remain, including variability in biological responses, lack of standardized dose-rate definitions, delivery system constraints, and the absence of robust clinical data. Although only limited clinical trials are currently underway, proton FLASH may enable safer hypofractionation, reirradiation, and dose escalation strategies in the future. Its successful clinical translation will require coordinated advances in biology, physics, and technology, supported by rigorous preclinical validation and carefully designed clinical trials.

Background: Vestibular schwannoma (VS) stereotactic radiosurgery (SRS) requires high target conformality and rapid dose falloff to spare adjacent organs at risk (OARs), particularly the brainstem. HyperArc (HA) is an automated noncoplanar volumetric-modulated arc therapy (VMAT) approach designed to standardize and streamline cranial SRS planning and delivery. We compared CyberKnife (CK) with HA for single-fraction VS SRS and evaluated the impact of multileaf collimator (MLC) leaf width. Methods: Fifteen VS cases previously treated with single-fraction CK SRS (12.5 Gy) were retrospectively replanned using HA. HA plans used four preconfigured noncoplanar partial arcs and were created with either a standard 5.0 mm MLC (HA-SMLC) or a 2.5 mm high-definition MLC (HA-HDMLC). HA plans were normalized to match the prescription dose target coverage of the corresponding CK plan for each of the patients. Endpoints included planning target volume (PTV) dosimetric statistics (Dmean, Dmin, Dmax, D98%), Paddick conformity index (PCI), Paddick gradient index (GI), ICRU Report 83 homogeneity index (HI), brain V12Gy, and brainstem Dmax. Because plans were generated for the same patients, paired comparisons were performed using two-sided Wilcoxon signed-rank tests (p < 0.05). Results: Both HA techniques achieved a higher near-minimum target dose than CK, with significantly higher PTV D98% (CK 12.35 ± 0.52 Gy; HA-SMLC 12.54 ± 0.28 Gy; HA-HDMLC 12.57 ± 0.35 Gy; p < 0.05). HA reduced target hotspots, with lower PTV Dmax than CK (CK 15.25 ± 0.32 Gy; HA-SMLC 14.70 ± 0.39 Gy; HA-HDMLC 14.73 ± 0.32 Gy; p < 0.05), and improved homogeneity and dose falloff as reflected by HI and GI (p < 0.05). CK achieved the highest conformity by PCI (p < 0.05), while HA-HDMLC improved PCI compared with HA-SMLC (p < 0.05). Brain V12Gy and brainstem Dmax were low and did not differ significantly among techniques. Conclusions: HA provides dosimetric performance comparable to CK for single-fraction VS SRS, with improved near-minimum PTV dose, reduced hotspots, and steeper dose gradients. Although CK showed the highest PCI overall, conformity improved with HA when a high-definition MLC was used. Overall, these findings support HA, particularly HA-HDMLC, as an efficient and clinically practical option for VS SRS treatment planning.

Background: Testicular shielding has long been used to reduce testicular dose during radiation treatment. However, quantitative evaluations of the effectiveness of such shielding in the literature vary substantially. Purpose: In this study, the dose reduction expected at both the testicular skin surface and the inside of the testes was evaluated under different irradiation conditions, to enable informed clinical decision‐making. Methods: A 3D printed scrotal phantom was designed to simulate patient testes and was composed of three layers to enable dose measurement inside the phantom. Gafchromic EBT3 film was used for dose measurements. The scrotal phantom was attached to a RANDO anthropomorphic phantom for computed tomography scanning and measurements. A commercial testicular shield with a lead wall thickness of 1.27 cm and a diameter of 6 cm was used for shielded measurements. The measured absolute dose was normalized to the delivered MU for each measurement to obtain a dose‐to‐MU value (cGy/MU). Both dose‐to‐MU values and shielding effectiveness were evaluated with a stationary anterior‐posterior beam at different distances from field edge to scrotal phantom. In addition, the energy dependence of shielding effectiveness was assessed using two volumetric modulated arc therapy (VMAT) plans with identical parameters and modulation but using 6 and 15 MV energies. Results: The shielded and unshielded dose‐to‐MU values generally decreased with increasing field‐to‐phantom distance for both surface and internal dose measurements. However, the shielding ratio remained relatively constant across distances, with a reduction factor of approximately 3.3 for surface dose and 2.7 for internal dose. Minimal energy dependence was observed in both internal and surface dose measurements, as well as in shielding effectiveness, across the two VMAT plans. The overall shielding ratio was approximately 2.3 for both plans. Conclusions: Testicular shielding reduced both surface and internal testicular dose by approximately a factor of 2 to 3, demonstrating consistent effectiveness across different irradiation geometries and photon energies.