Earticle

Background: In the simulation of gamma-ray spectral response from a scintillation detector, the energy deposited in the detector is often calculated from the energy lost by each incident gamma ray due to the interaction, no matter where it may happen. In reality, the light collection efficiency of the scintillator will not be uniform over the entire scintillator, which affects the spectral response that can actually be obtained by the scintillator. The energy resolution and peak efficiency, as well as overall shape of the gamma-ray spectrum can deviate from reality. Materials and Methods: We simulated the gamma-ray response of a 5.08 cm×5.08 cm (2˝×2˝) Cs2LiYCl6:Ce (CLYC) scintillation detector considering the transport of associated information carriers: gamma rays only, gamma rays and electrons, and scintillation photons additionally, using Monte Carlo N-Particle version 6.1 (MCNP6.1) and GEometry ANd Tracking version 4 (GEANT4) code. The effect of the secondary particle transport was analyzed by comparing the simulation and measurement results. Results and Discussion: The absolute peak efficiency calculated from the simulation that includes electron transport is closer to the measurement result than that from the simulation considering only gamma‐ray transport. The discrepancy decreased from 24.6% (gamma only) to 21.2% (including electron transport) by MCNP6.1 calculation, and from 13.6% (gamma only) to 7.9% (including electron transport) by GEANT4 calculation. Through simulation considering the transport of scintillation photons, the phenomenon of peak broadening on the energy spectrum became observable. Conclusion: In the gamma-ray response simulation of scintillation detectors, we confirmed that the deviation from the measurement results was reduced by including secondary particle transfers into consideration.

Background: Diagnostic reference levels (DRLs) are integral to optimizing the patient dose in diagnostic radiology, and yet data for low- and middle-income countries are limited. Here, we propose the first Ghanan national DRLs (NDRLs) for selected radiographic procedures, aiming to enhance dose standardization and patient safety. Materials and Methods: A nationwide cross-sectional dosimetry survey of 41 radiologic systems reviewed eight frequently performed examinations across 7,643 adult patients. An indirect method based on X-ray tube output measurements and technical exposure factors was used to evaluate entrance surface dose in those patients. The 75th percentile of each facility’s median entrance surface dose for each examination/projection was proposed as the NDRL. The resulting NDRLs were compared with international NDRLs to assess dose variability and levels against global standards. Results and Discussion: The proposed NDRLs are chest posterior–anterior (PA, 0.36 mGy), chest lateral (LAT, 0.97 mGy), pelvis anterior–posterior (AP, 2.77 mGy), skull AP/PA (2.00 mGy), skull LAT (1.75 mGy), lumbar spine AP (3.64 mGy), lumbar spine LAT (7.12 mGy), and abdomen AP (2.44 mGy). Although doses sometimes varied across facilities, particularly in high-attenuation procedures such as lumbar spine LAT, the chest PA values aligned closely with the international references. The results highlight the need to optimize imaging protocols and equipment performance and to invest in modern imaging equipment with advanced dose reduction capabilities to augment patient dose optimization initiatives in Ghana. Conclusion: We propose Ghana’s first NDRLs for general radiography procedures to guide national dose optimization efforts. Implementing these NDRLs would help to standardize imaging protocols, minimize patient exposures, and bolster diagnostic efficacy. Ongoing collaboration between regulatory authorities, healthcare facilities, and researchers is essential to implement and ensure sustained improvements in patient radiologic safety.

Background: Boron neutron capture therapy (BNCT) is a targeted radiotherapy that selectively destroys cancer cells by delivering compounds enriched in boron-10 (10B) that preferentially accumulate in tumors. When exposed to low-energy neutrons, 10B undergoes a nuclear reaction that produces high-linear energy transfer particles that kill adjacent tumor cells while sparing healthy tissues. Real-time monitoring of boron distribution and the neutron irradiation is critical to optimize treatment efficacy and minimize collateral damage. Materials and Methods: We evaluated a single-photon emission computed tomography (SPECT) configuration for simultaneous monitoring of boron spatial distribution and neutron irradiation patterns. Monte Carlo simulations were performed with the Monte Carlo N-Particle version 6.2 (MCNP6.2) using a male Oak Ridge National Laboratory stylized phantom. The simulations modeled prompt gamma emissions at 0.478 MeV (from 10B neutron capture) and 2.2 MeV (from hydrogen neutron capture) and the detection response of a four-head cadmium zinc telluride (CZT) SPECT system. Results and Discussion: The SPECT system localized regions of boron uptake in the phantom using 0.478 MeV emissions with good spatial localization. Although the system detected 2.2 MeV gamma rays from hydrogen neutron capture, reconstructed images from this energy showed diffuse distributions and did not provide clear directional information about the neutron source. These findings indicate strong performance for boron mapping but limited capability for precise neutron-source directionality using 2.2 MeV gamma emissions in the present configuration. Conclusion: SPECT-based imaging with a CZT detector shows feasibility for real-time boron mapping in BNCT. However, further work on detector geometry, collimation, and reconstruction algorithms is needed to improve sensitivity at clinically relevant boron concentrations and to enhance directional sensitivity for neutron-field assessment.

Background: This study examines South Korea’s administrative agencies regulating radiation risks, focusing on organizational structures, legal frameworks, and delegated regulatory powers. It highlights challenges from fragmented statutes, inconsistent standards, and scientific uncertainties, emphasizing the need for coherent and effective regulatory governance to protect public safety. Materials and Methods: This qualitative study identified domestic administrative agencies and relevant legislation regulating radiation risks through expert consultations, analysis of prior studies, and systematic searches of the National Law Information Center. Results and Discussion: In South Korea, the regulation of radiation risks is fragmented across 12 administrative agencies, including the Nuclear Safety and Security Commission, Ministry of Health and Welfare, Ministry of Agriculture, Food and Rural Affairs, Ministry of Oceans and Fisheries, Ministry of Environment, Ministry of Food and Drug Safety, Ministry of the Interior and Safety, National Intelligence Service, Ministry of Employment and Labor, Ministry of Science and ICT, Ministry of Trade, Industry and Energy, and Ministry of Land, Infrastructure and Transport. A total of 32 laws under these agencies govern radiation risk regulation. Each administrative agency is involved in the oversight of high-level and low-level radiation, radiological emergencies, remediation, and compensation measures. While these agencies oversee high- and low-level radiation, radiological emergencies, and remediation or compensation measures, no single body exercises comprehensive regulatory authority. This dispersed framework results in inconsistencies in dose limits, measurement protocols, and definitional standards, compounded by variations in subordinate regulations and administrative notifications. The structural and legal fragmentation highlights the imperative for enhanced inter-agency coordination or institutional consolidation to ensure coherent and effective governance of radiation risks. Conclusion: South Korea’s radiation risk regulation requires a unified legal framework to integrate multiple administrative agencies. A foundational statute, such as the Nuclear Safety Act, is crucial for standardizing risk evaluation and measurement methodologies across ministries.

Background: This study systematically compared the performances of fast non-local means (FNLM), conventional non-local means (NLM), and adaptive non-local means (ANLM) algorithms for Rician noise reduction in clinical breast magnetic resonance imaging (MRI). Materials and Methods: Rician noise with standard deviations of 0.05, 0.10, and 0.15 was synthetically introduced into pre-contrast T1-weighted breast MRI images obtained from 50 patients in a publicly available clinical dataset. For each noise level, the FNLM search window size was optimized using a root mean square error (RMSE)-based tuning procedure. The optimized FNLM was then quantitatively compared with NLM and ANLM. Image quality was assessed using RMSE, structural similarity index (SSIM), high-frequency error norm (HFEN), gradient magnitude similarity deviation, and edge preservation index (EPI). Computational efficiency was evaluated in a MATLAB (MathWorks) environment using central processing unit-based processing. Results and Discussion: The relative performance of FNLM varied according to noise level and evaluation metric. Compared with ANLM, FNLM achieved lower RMSE and HFEN and higher SSIM and EPI across most noise levels, while showing comparable or improved performance relative to NLM. Linear mixed-effects analysis confirmed significant algorithmic differences depending on noise severity. Regarding computational efficiency, FNLM was approximately 7.8–25.1 times faster than ANLM and 2.7–3.2 times faster than NLM across noise levels. Conclusion: The optimized FNLM algorithm provides competitive denoising performance while substantially improving computational efficiency in clinical breast MRI with Rician noise.

Background: The objective of this study is to investigate the suitability of moss and lichen as bioindicators that can substitute for existing bioindicators, such as mugwort and pine needles. Materials and Methods: Fifteen moss (Hypnaceae) and lichen (Parmeliaceae) samples were collected from three differing ecological environments in Korea: a high-altitude mountainous region; a high-humidity coastal area; and an urban community park. The samples were collected from tree trunks, rocks, and soil substrates and were dried, ground, sieved, ashed, and enclosed in polyethylene containers for activity concentration measurements via gamma spectrometry. The reference date for decay correction was based on sampling dates and measured activity. Results and Discussion: The activity concentrations of 137Cs, 40K, and 7Be in mosses by dry weight were 1.89–47.8, 156–506, and 60.6–1,227 Bq· kg−1, respectively. The concentration values varied depending on the substrate and ecological environment. The moss accumulated greater amounts of 137Cs than the lichen, which was attributed to the greater surface-to-volume ratio of moss. The 137Cs activity concentrations in moss adhered to tree trunks were substantially lower than those in moss covering rock or soil. This was attributed to differences in 137Cs resuspension effect, which may occur through the spattering of raindrops and the effects of wind. The transfer factors of radionuclides from soil to moss were 0.61, 0.65, and 0.46 for 137Cs, 40K, and 7Be, respectively. Conclusion: This preliminary study showed that moss accumulates a considerably higher amount of 137Cs than mugwort. Therefore, mosses seem to be more suitable bioindicators than mugwort for the routine monitoring of radioactive fallout in Korea. However, further research using various moss species from ecological environments and sampling sites with different topography and other geographical properties is needed to reduce the uncertainties in the values estimated in the present study.

Background: This study aims to protect workers and participants from occupational radiation exposure in non-destructive testing (NDT) laboratories located at the B.J. Habibie Science and Technology Park (KST) in Indonesia. These laboratories use X-ray and gamma-ray sources, specifically Ir-192 and Co-60 for research and certification purposes. Materials and Methods: The study used an experimental approach and evaluated radiationbased and also non-radiation-based NDT methods in compliance with the International Organization for Standardization (ISO) 9712 standards. Key radiation protection strategies included infrastructure optimization, shielding enhancement, and routine exposure monitoring using thermoluminescent dosimeters. Results and Discussion: The highest recorded annual occupational dose was just 3.32 mSv, well under the regulatory limit of 20 mSv, representing only 16.6% of the threshold allowed. The implementation of internationally recognized standards, including International Atomic Energy Agency General Safety Requirements Part 3: Radiation Protection and Safety of Radiation Sources (GSR Part 3), General Safety Guide No. 7 (GSG-7), Specific Safety Guide No. 46 (SSG-46), relevant ISO standards, and Nuclear Energy Regulatory Agency as known in Indonesia Badan Pengawas Tenaga Nuklir regulations, ensured regulatory compliance and the establishment of radiation safety framework within the certification body. Conclusion: The findings demonstrate that integrated safety practices, when aligned with national and international regulations, effectively minimize radiation exposure among NDT workers. The results provide practical insights for strengthening occupational radiation protection in other high-risk facilities and serve as a benchmark for continuous safety improvement and regulatory enforcement within Indonesia’s emerging industrial radiography sector.