International journal of radiation biology最新文献

Purpose: Preserving the integrity of the genome is critical to healthy cellular growth and development. Under normal circumstances, the eukaryotic mismatch repair (MMR) machinery is effective at detecting DNA polymerase errors and maintaining the fidelity of the genome. However, cells with inactivated MMR machinery are prone to the accumulation of mutations and tumorigenesis. This study explores the theoretical potential of rhodium-99- and iodine-123-labeled DNA metalloinsertors as Auger electron-emitting radiotherapeutics for cancers characterized by MMR deficiency.

Materials and methods: A Monte Carlo code was developed in MATLAB^® to obtain Auger electron energy spectra for ⁹⁹Rh and ¹²³I. Using Geant4 track structure simulations, we determined the difference in effectiveness of these two Auger electron-emitting radionuclides in direct damage to DNA and the ability to produce double strand break damage (dsb) to the DNA comparing two different constructors 'G4EmDNAPhysics_option2' and 'G4EmDNAPhysics_option4'.

Results: Differences in the Auger electron emission spectra of ⁹⁹Rh and ¹²³I arise from their electronic structure: ¹²³I favors more complex cascades and ultra-low-energy electrons, while ⁹⁹Rh produces electrons with energies more suited to DNA damage. Despite similar total electron yields, the emissions of ⁹⁹Rh are more effective at causing dsb (0.71 vs. 0.60 dsb/decay for ⁹⁹Rh and ¹²³I, respectively, using constructor 'G4EmDNAPhysics_option2' and 0.81 dsb/decay for ⁹⁹Rh vs. 0.71 dsb/decay for ¹²³I when using 'G4EmDNAPhysics_option4'.

Conclusion: This theoretical study leverages both simulation and comparative analyses to identify ⁹⁹Rh as a promising Auger electron-emitting nuclide for radiotheranostics, as it offers superior DNA damage efficacy compared to ¹²³I.

Purpose: We developed a new computer program for the application of electron spin resonance (ESR) to dosimetry of wild animals related to the Fukushima Daiichi Nuclear Power Plant accident.

Materials & methods: The ESR spectra of carbonate radicals and other inorganic radicals are calculated by the complete elliptic integral. A simulated annealing method is implemented for the parameter optimization. A cost function is designed to include the second derivative form of the microwave absorption spectrum to improve the fitting accuracy. As a testing ground for the developed code, we prepared tooth enamel samples from a Japanese macaque captured in a control area.

Results: The developed code well reproduced the measured ESR spectrum. With a test spectrum, we demonstrated that the cost function that includes the second derivative form of the microwave absorption spectrum is helpful for the precise analysis of the low-dose enamel samples. The smoothness of the ESR spectrum plays an important role in utilizing this feature.

Conclusion: The developed computer code can be used to analyze the ESR spectrum of tooth enamels of Japanese macaques. A precise analysis is essential to lower the detection limit and expand the applicability of ESR dosimetry. The code is independent of the computer operating system and is available publicly.

Purpose: Cytogenetic biodosimetry is used for radiation dose assessment by evaluating chromosomal aberrations in peripheral blood lymphocytes. However, high-dose radiation may cause low absolute lymphocyte counts (ALCs), making it difficult to obtain sufficient metaphase spreads for analysis. This study aimed to optimize centrifugation settings to enrich metaphase spreads, particularly for lymphocytopenic patients.

Materials and methods: Peripheral blood samples from four healthy donors and one lymphocytopenic patient were collected. Lymphocytes were harvested using one of four centrifugation settings. After an additional low-speed centrifugation step (200 × g for 1 minute) in each experiment, we evaluated slide quality using mitotic index (MI) and metaphase frequency (MF), which were calculated by the number of metaphases and blasts using Metafer 4 software.

Results: We established an automatic measurement method for metaphases and blasts, adjusting the settings of Metafer 4. In four healthy donors, the strongest centrifugation (Exp. 4, 879 × g for 5 minutes) yielded the highest number of 'all cells' after harvest. Incorporating an additional low-speed centrifugation step significantly increased MF by 1.5- to 2-fold across all settings, with the greatest improvement observed in Exp. 4. This approach was applied to a lymphocytopenic patient, resulting in a 3.5-fold improvement of MF and the production of high-quality slides. MI was not significantly affected by centrifugation.

Conclusions: The combined high-speed and additional low-speed centrifugation method increased MF, improved slide quality by eliminating lower-density cells, and made it easier to analyze metaphase spreads. This method could be used for obtaining sufficient metaphase spreads in lymphocytopenic patients.

Purpose: To assess the radioecological consequences of the technogenic transformation of the Chornobyl NPP cooling pond aquatic ecosystem and its impact on the blood system of Myodes glareolus, a typical small rodent species in the Chornobyl exclusion zone.

Materials and methods: Animals were captured in the drained areas of the cooling pond and nearby areas. Radiometric surveys of the animals' natural habitat and soil sampling were conducted. γ-β-spectrometry was used to measure radionuclide levels (¹³⁷Cs and ⁹⁰Sr) in soil and animal bodies. Absorbed dose rates were calculated. Blood smears, bone marrow and spleen imprints were prepared and stained using the standard Pappenheim method.

Results: Activity of ¹³⁷Cs and ⁹⁰Sr in soil and animal samples, external/internal doses in animals were estimated. Radioecological assessment showed that radionuclide contamination in the drained areas did not exceed that of the adjacent territory. In exposed animals, similar hematopoietic alterations were observed, including disrupted differentiation and maturation of bone marrow cells, particularly in erythroid and granulocytic lineages. However, these blood abnormalities were less pronounced in animals from the drained zones.

Conclusions: Draining the cooling pond, despite the expected high radionuclide concentrations in bottom sediments, did not cause significant changes in surface soil contamination. While bank voles showed deviations in blood parameters compared to reference values, differences between exposure groups were generally not significant. These findings support continued monitoring of radiobiological effects associated with the transforming of radiation-contaminated aquatic ecosystems into terrestrial.

Purpose: This study reviews how ionizing radiation (IR) induces alternative splicing (AS) in non-tumor and tumor cells under both ex vivo and in vivo irradiation conditions. The relevance and limitations of IR-induced AS in identifying potential biomarkers are highlighted for two main applications: biodosimetry and radiotherapy.

Conclusions: Radiation promotes alterations in AS, which may differentially affect the response in both tumor and non-tumor cells. This response can occur in genes that change their overall expression as well as in those that remain unaltered in response to IR. Although cis-regulators modulate AS, trans-regulators like splicing factors are more involved in the IR response. Variants of key genes involved in the DNA damage response (DDR) are regulated in non-tumor cells while they are often deregulated in tumor cells favoring radioresistance. Identifying IR-induced AS variants could enhance the sensitivity of biodosimeters for dose estimation and biomarkers for radiosensitivity, offering potential strategies to personalize radiotherapy and improve outcomes. New and advanced sequencing technologies will allow variant identification important for the field of radiobiological research.

The roundtable discussion at EPR BioDose 2024 focused on identifying challenges for using biodosimetry in a large nuclear incident and exploring potential solutions to strengthen preparedness and response frameworks. This report outlines the major themes discussed, including advancements in techniques, challenges in scaling operations, and the future of biodosimetry in emergency response. Initiated by International Association of Biological and EPR Radiation Dosimetry (IABERD), a group of experts comprised of professionals in academia, government and other agencies, were asked to discuss the question: 'When and how should biodosimetry be used for an unplanned radiation explosion in the short or long term?' This question challenged participants to consider a range of scenarios, from immediate triage in the aftermath of an incident to long-term health monitoring and risk assessment. Panelists acknowledged that, while biodosimetry plays a crucial role in rapidly assessing exposure levels to guide medical response, its practical implementation can vary based on scale, resources, and timing. They emphasized that in the short term, methods that provide quick, large-scale screening are important, whereas long-term strategies might include more detailed biological assessments to understand cumulative effects and potential health risks. Despite the difficulty of a one-size-fits-all approach, the insights gathered aimed to inform strategies that balance speed, accuracy, and sustainability in biodosimetry practices. Finally, panelists emphasized the need for better communication about preparedness with the general public and healthcare providers, and a more collaborative approach that also takes into account evaluating the practicality of various methods for triage or guiding treatment.

Purpose: Interdisciplinary team collaboration is a key element of discovery and advancement in oncology science and medicine. This fact is well-recognized by both laboratory and physician scientists and yet, most cancer research trainees are minimally exposed to and ill prepared in the collaboration skills required for them to be successful in the future. Similarly, near-peer mentoring, the benefits of which have been broadly published for precollegiate and undergraduate programs, is usually not a formal training component for doctoral and postdoctoral oncology trainees. At the University of Florida, the Team-based Interdisciplinary Cancer Research Training (TICaRT) Program seeks to address this unmet need by offering a unique opportunity for trainees to develop interdisciplinary skills in cancer research and gain collaborative expertise through team-based learning and near-peer mentoring.

Conclusion: Active transdisciplinary research collaboration drives cancer discovery, knowledge, and treatment. Providing opportunities for trainees to participate in collaborative research experiences by incorporating team science and near-peer mentoring concepts as integral components of their training would greatly aid their preparation to become successful next-generation cancer researchers.

Purpose: Dosimetry reporting in radiobiological studies is frequently incomplete and leads to poor replicability. As the main objective of biological dosimetry is estimating an exposure dose reflecting a whole-body dose equivalent to assess acute and delayed health risks, dosimetry reporting is even more crucial. This study aims to evaluate the quality of the dosimetry reporting and irradiation parameters related to biological dosimetry publications.

Material and methods: 114 publications over a period of 94 years focused on biological dosimetry studies were analyzed. Nineteen parameters distributed into four categories (source specification, irradiation geometry, calibration, and irradiation details) were scored to evaluate the quality of the dosimetry reporting.

Results: We show that, even though parameters such as radiation type, sample type, and dose are systematically reported, and source type, energy/voltage, dose rate, and exposure type in more than 80% of publications, several crucial parameters are missing. Specifically, information regarding the dosimetry protocol, setup, and calibration are often not reported, making it impossible to reproduce the experiments.

Conclusions: This study highlighted that certain parameter, such as the source used or the irradiation dose, are very often well-reported. Still, critical parameters such as the dosimetric quantity or the method used for dosimetric measurements have to be systematically added. Efforts already underway in this area must be continued to further improve the description of irradiation parameters for radiobiology studies.

Purpose: The purpose of this study was to evaluate the thickness and biomechanical parameters of the sternocleidomastoid muscle (SCM) before, during, and after radiotherapy using ultrasound elastography to predict radiotherapy-induced muscle fibrosis.

Materials and methods: The mean daily absorbed doses of 20 SCMs were determined. To find out the Young and shear modulus, shear wave elastography (SWE) and the B-mode sequential images processing method were implemented. In the B-mode sequential images processing method, by administering dynamic stress, the Young and shear modulus were estimated utilizing the maximum gradient and the block-matching algorithms, respectively. The imaging was done before, during the third and sixth weeks of treatment, and 3 months after radiotherapy.

Results: There was a statistically significant increase in the maximum thickness during the sixth week compared to before radiotherapy (p = .043). However, this parameter did not change significantly 3 months later (p = .095). The Young modulus (p = .611) derived from SWE did not differ significantly throughout any of the weeks of radiotherapy. But Young and shear modulus increased significantly in the B-mode sequential images processing method before and during the third and sixth weeks of treatment (p = .001). The outcomes observed 3 months after radiotherapy revealed a statistically significant increase in both Young modulus (p = .029) and shear modulus (p = .004) compared to pre-radiotherapy.

Conclusion: The Young modulus and shear modulus are introduced as biological markers used to detect the onset of the fibrosis process during the initial radiotherapy fractions.

Purpose: This study aimed to quantitatively assess changes in lung perfusion after thoracic radiotherapy in lung cancer patients.

Materials and methods: Patients underwent chest computed tomography (CT) for pulmonary vasculature analysis before radiotherapy and at 3 and 12 months after radiotherapy. The correlation between the percentage decrease in lung perfusion after radiotherapy and the delivered radiotherapy dose was analyzed.

Results: The ipsilateral lung, where the primary tumor was located, received a significantly higher dose than the contralateral lung (mean dose: 22.9 Gy vs. 6.8 Gy). At 3 months, significant reductions in lung perfusion parameters were observed in the ipsilateral lung (total blood volume (TBV): 13.8%, blood volume in vessels with cross-sectional areas of ≤10 mm²: 12.6%, blood volume in vessels with cross-sectional areas of ≤5 mm²: 11.7%, subpleural vessel count: 21.1%, subpleural vessel area: 16.9%, and subpleural vessel density: 12.3%). Significant negative correlations between perfusion parameters and the radiation dose delivered to the ipsilateral lung were observed. For every 1-Gy increase in the mean dose for the ipsilateral lung, TBV decreased by 0.852% (p = .044), and for every 1% increase in the percentage of lung volume that received more than 20 Gy, TBV decreased by 0.402% (p = .048). The 3-year overall survival of the patients was 75%. No significant association between baseline perfusion parameters and survival was observed.

Conclusions: Thoracic radiotherapy significantly reduced pulmonary perfusion, especially in the ipsilateral lung. The reduction in perfusion correlated with the radiation dose. These findings underscore the impact of radiation-induced damage on perfusion.