Journal of Radiation Research最新文献

This study aimed to evaluate the recent trends in single-fraction conventional radiotherapy (CRT) as palliative treatment in Japan, using data from the National Database published by the Ministry of Health, Labor, and Welfare. Data from fiscal year (FY) 2014 to FY2022, specifically related to the utilization of single-fraction CRT, were analyzed. Multi-fraction CRT, stereotactic body radiotherapy (SBRT), intensity-modulated radiotherapy (IMRT), and brachytherapy were excluded. The primary outcome was the cumulative and annual number of single-fraction CRT courses. Additionally, quarterly course data from FY2019 to FY2022, the period for which monthly data were available, were assessed to evaluate the impact of the coronavirus disease 2019 (COVID-19) pandemic on single-fraction CRT utilization. Of the total 2 315 607 radiotherapy courses, we identified 33 221 single-fraction CRT courses after excluding multi-fraction CRT (n = 1 835 650), SBRT (n = 33 935), IMRT (n = 332 827), and brachytherapy (n = 113 195). The annual number of single-fraction CRT courses increased from 1730 in FY2014 to 5642 in FY2022, with an average annual growth rate of 0.28 (range: -0.07 to 0.65). Outpatient courses significantly increased, particularly from FY2019 onward, surpassing inpatient courses in FY2022 (2914 vs 2728). The highest annual increase was observed in FY2020, particularly from April to December, although this upward trend did not persist in 2021. In conclusion, single-fraction CRT has exhibited a consistent upward trend, highlighting its expanding role in palliative radiotherapy. Although the COVID-19 pandemic temporarily accelerated this trend, its impact has already subsided, with growth rates returning to pre-pandemic levels.

Medulloblastomas are one of the most common malignant cancers of the central nervous system in children. Proton beam therapy (PBT) is expected to provide equivalent tumor control to photon therapy while reducing the various adverse events caused by irradiation. Few studies have considered the cost-effectiveness of PBT for pediatric medulloblastoma, considering the multiple adverse effects and reflecting on the latest treatment advancements. A cost-utility analysis of PBT for pediatric medulloblastoma was conducted in a Japanese setting and compared to conventional photon therapy. The analysis was conducted from the public healthcare payer's perspective, and direct costs for the treatment of radiation therapy and radiation-induced adverse events were included. A Markov model was used, and the health states of secondary cancer, hypothyroidism and hearing loss were defined as adverse events. The time horizon was the lifetime. Incremental cost-effectiveness ratio (ICER) was used as a measurement of cost-effectiveness, with quality-adjusted life years (QALYs) used as an outcome. The costs were estimated from the national fee schedule, and the utility and transition probabilities were estimated from published literature. PBT incurred an additional 1387116 Japanese yen (JPY) and 1.56 QALYs to the comparator. The ICER was JPY 887053/QALY, indicating that PBT was cost-effective, based on the reference value of JPY 5 million/QALY used in the Japanese cost-effectiveness analysis. Deterministic sensitivity analysis showed that the ICER ranged from JPY 284782/QALY to JPY 1918603/QALY as a result of deterministic sensitivity analysis, and probabilistic sensitivity analysis showed that PBT was cost-effective, with a probability of 91.7%.

Recently, ultra-high dose rate (> 40 Gy/s, uHDR; FLASH) radiation therapy (RT) has attracted interest, because the FLASH effect that is, while a cell-killing effect on cancer cells remains, the damage to normal tissue could be spared has been reported. This study aimed to compare the immune-related protein expression on cancer cells after γ-ray, conventionally used dose rate (Conv) carbon ion (C-ion), and uHDR C-ion. B16F10 murine melanoma and Pan02 murine pancreas cancer were irradiated with γ-ray at Osaka University and with C-ion at Osaka HIMAK. The dose rates at 1.16 Gy/s for Conv and 380 Gy/s for uHDR irradiation. The expressed calreticulin (CRT), major histocompatibility complex class (MHC)-I, and programmed cell death 1 ligand (PD-L1) were evaluated by flow cytometry. Western blotting and PCR were utilized to evaluate endoplasmic reticulum (ER) stress, DNA damage, and its repair pathway. CRT, MHC-I on B16F10 was also increased by irradiation, while only C-ion increased MHC-I on Pan02. Notably, PD-L1 on B16F10 was increased after irradiation with both γ-ray and C-ion, while uHDR C-ion suppressed the expression of PD-L1 on Pan02. The present study indicated that uHDR C-ion has a different impact on the repair pathway of DNA damage and ER than the Conv C-ion. This is the first study to show the immune-related protein expressions on cancer cells after uHDR C-ion irradiation.

Radiation therapy is used in the treatment of various cancers, and advancements in irradiation techniques have further expanded its applicability. For radiation oncologists, predicting adverse events remains a critical challenge, even with these technological advancements. Although numerous studies have been conducted to predict individual radiosensitivity, no biomarkers have been clinically applied thus far. This review focuses on γ-H2AX foci and chromosomal aberrations, providing an overview of their association with normal tissue toxicities.

Following the 2011 Fukushima Daiichi Nuclear Power Plant accident, public behaviors have been marked by excessive avoidance and stigma, driven by fear and uncertainty regarding radiation exposure and its health implications. Despite extensive media dissemination of information on radiation, the precise nature of the public's knowledge, beliefs and the resultant behavioral responses remain unclear. This study aimed to segment the population based on their attitudes, knowledge, beliefs and anxiety levels about radiation, correlating these factors with their cognitive and behavioral responses to radiation exposure. Surveying 2400 individuals, we identified seven distinct segments that illustrated a spectrum of health concerns, even among those well-informed about radiation. Notably, individuals with higher health anxiety were found to reject discriminatory prejudices linked to radiation, yet they tended to distrust official information, potentially as a psychological mechanism to justify their avoidance behaviors. These findings underscore the need for tailored communication strategies that address the complex landscape of radiation-related perceptions and misinformation.

Radiation induces various changes in biological specimens; however, the evaluation of these changes is usually complicated and can be achieved only through investment in time and labor. Optical methods reduce the cost of such evaluations as they require less pretreatment of the sample, are adaptable to high-throughput screening and are easy to automate. Optical methods are also advantageous, owing to their real-time and onsite evaluation capabilities. Here, we discuss three optical technologies to evaluate the effects of radiation on biological samples: single-molecule tracking microscopy to evaluate the changes in the physical properties of DNA, Raman spectral microscopy for dosimetry using human hair and second-harmonic generation microscopy to evaluate the effect of radiation on the differentiation of stem cells. These technologies can also be combined for more detailed information and are applicable to other biological samples. Although optical methods are not commonly used to evaluate the effects of radiation, advances in this technology may facilitate the easy and rapid assessment of radiation effects on biological samples.

An accurate understanding of the population is essential for the development of medical care and social resources. However, the development of transportation networks has increased temporal and spatial fluctuations in the population, making it difficult to accurately forecast medical care demand, especially during disaster recovery. This study examined the population movement in areas affected by the Fukushima Daiichi nuclear power plant accident using demographic data. The target area includes two cities, seven towns, and three villages that are in the evacuation zone. Using a population estimation that reflects changes in population by time of day, which was obtained from a mobile phone company (NTT DOCOMO), we applied clustering analysis to examine the population dynamics over a 4-year period. From 2019 to 2022, the population increased in eight areas and decreased in four areas. The population was further classified into five groups, identifying the unique characteristics and fluctuations of each group. Different regions had different percentages of groups reflecting the characteristics of their populations. The differences among the regions and demographic transition showed the potential to understand the challenges of recovery and to use the data to inform healthcare planning and social policies. This method, which utilizes estimated population data, is also applicable to the study of medical resources and social policies in the event of future disasters and may be useful in analyzing regional characteristics in detail.

The more science progresses, the more life and society change. Medicine also changes with the times and the culture. This is also true for radiation emergency medicine, which includes dose-assessment leading to diagnosis, treatment, medical follow-up and prognosis of persons who have developed acute injury or illness due to radioactive contamination or radiation exposure. Before the report of X-rays by Roentgen, there was evidence that X-rays had been emitted from the electrically excited Crookes tube and that skin injury had been caused by the X-rays. Thus, the history of radiation and its exposure started before Roentgen. During the early stage of radiation use, people were simply exposed to radiation but were unaware of any danger. Radioactive materials were found soon after Roentgen's report, and contamination with these materials occurred. Together with the development of science and technology, sophisticated radiation devices were produced, and the use and application of radiation became much enhanced. New radionuclides were found one after another, leading to identification of different qualities of radiation. Development of nuclear physics allowed people to artificially produce radionuclides and to construct a nuclear reactor. After World War II, nuclear power plants were constructed, and related facilities such as nuclear fuel processing, reprocessing and spent fuel storage facilities were built. If radiation accidents or events occur at such facilities, radiation exposure with thermal or chemical burns could occur. Together with the expansion of globalism in the world and division in the society, there are now increasing concerns regarding the malicious usage of radiation by radiological dispersal devices (RDDs) including a dirty bomb. Upon detonation of RDDs, blast and thermal injuries with radiation exposure could be caused. In the present society, the natures of exposure to radiation and contamination with radioactive materials have become much more complicated. Not even mentioning the atomic bomb, the detonation of RDDs also necessitates scenarios of medical responses to complicated injuries and the involvement of numbers of people. This article looks back at the history of radiation and addresses the medical responses to radiation injuries that change with the times.

We previously reported endogenous activation of the DNA damage response (DDR) in the epidermis surrounding basal cell carcinoma resected from Nagasaki atomic bomb survivors, suggesting the presence of genomic instability (GIN) in the survivors as a late effect of radiation. Dual-color immunofluorescence (IF) analysis of TP53-binding protein-1 (53BP1) and a proliferative indicator, Ki-67, to elucidate GIN in tumor tissues revealed that abnormal 53BP1 expression is closely associated with carcinogenesis in several organs. The present study aimed to confirm the presence of radiation-induced GIN in the non-neoplastic epidermis of patients with radiation-induced skin cancer. Formalin-fixed paraffin-embedded tissues were obtained from all participants between 2008 and 2019 at the Nagasaki University Hospital. 53BP1 nuclear expression was examined using dual-color IF analysis with Ki-67 expression to assess the extent and integrity of the DDR. Expressions of gamma-H2AX, p53 and p21 were also analyzed using the dual-color IF analysis for their association with 53BP1. The results of this study provide evidence for sporadic activation of the DDR in medically irradiated and ultraviolet-exposed epidermis as a long-lasting radiation effect, which is a predisposition to skin cancer. Furthermore, the incidence of abnormal 53BP1 expression in cancer cells was higher than in non-neoplastic epidermal cells surrounding cancer, suggesting a correlation between the type of 53BP1 and the malignant potential of skin tumors. This study highlights the usefulness of dual-color IF for 53BP1 (and Ki-67) as an indicator to estimate the level of GIN as a long-lasting health effect of radiation exposure.

Conventional radiation therapy can restore the ability of cells to undergo immunogenic cell death. Recent preclinical studies suggest that targeted radionuclide therapy, which delivers radiation to tumors at a continuous low dose rate, also stimulates the immune system and offers a promising approach for overcoming resistance to immune checkpoint inhibitors. In this context, we examined the growing body of preclinical and clinical findings showing that the immune system can be activated by the release of extracellular vesicles from irradiated cells, contributing to the antitumor immunity.