Journal of Radiation Research最新文献

In the last decade, the role of radiotherapy in rectal cancer has changed significantly with the introduction of total neoadjuvant therapy (TNT) and nonoperative management (NOM). For the setting of irradiation field in rectal cancer, the pararectal, lateral lymph nodes, and those along the inferior mesenteric artery (IMA) are most important. In total mesorectal excision (TME), the root of the IMA is dissected. In the atlas of pelvic irradiation for rectal cancer, the setting of the upper margin of the mesorectum varies from atlas to atlas, and no atlas sets the upper margin of the mesorectum to the root of the IMA. In particular, there is no consensus on the definition of anatomical boundaries regarding the lymph nodes along the superior rectal artery (SRA). The upper margin of the irradiation field in clinical trials of preoperative radiotherapy and TNT is generally set at the level of the internal and external iliac artery branches, L5/S1, or S2/S3. However, it is not necessary to include the entire mesorectum to the root of the IMA in patients undergoing preoperative radiotherapy plus TME. Conversely, for patients receiving NOM, the irradiation field may have to include the mesorectum to the IMA root, though the incidence of lymph node metastasis and gastrointestinal adverse events merits consideration. It is increasingly important to determine the extent of clinical target volume around the SRA region and the setting of the upper margin of the irradiation field after formulating the treatment policy together with the surgeons and medical oncologists.

Studies on the atomic bomb have reported a relatively high incidence of acute symptoms, even at below the threshold dose of radiation, and are therefore assumed to include symptoms caused by non-radiation factors. In this study, to investigate the influence of external injuries and burns on symptom expression and the possibility of distinguishing radiation-induced symptoms, we reanalysed data from the survey conducted immediately after the atomic bombing of Nagasaki. The adjusted odds ratios (ORs) of radiation per 1 Gy for the occurrence of 16 symptoms ranged from 1.14 to 1.46, based on sex, age at the time of the bombing, radiation dose, external injuries, and burns. This study also included 243 deaths, and thus provides information not seen in other studies, such as the frequency of symptoms in deaths and ORs for symptom occurrence. However, the adjusted ORs for external injuries or burns were smaller than the unadjusted ORs, suggesting that external injuries and burns confound the development of radiation-induced symptoms. Symptom data obtained from interviews such as those used in this study may not be appropriate for use alone because such data include non-radiation factors. Radiation-induced symptoms are often considered to be a syndrome, and the multiple correspondence analyses also revealed that high-dose exposure is associated with nausea and vomiting, subsequent epilation and bleeding tendency as a bone marrow disorder, and inflammation symptoms due to a weakened immune system. Thus, radiation exposure may be indicated by not just one, but rather, a combination of symptoms.

This study aimed to compare outcomes between carbon ion radiotherapy (C-ion RT) and transarterial chemoembolization (TACE) in patients with unresectable solitary hepatocellular carcinoma (HCC) >3 cm. Fifty-eight patients who had been treated with C-ion RT (C-ion RT group) and 34 treated with TACE (TACE group) were retrospectively enrolled between January 2016 and December 2021. Propensity score matching was conducted to account for differences between the two groups. The median follow-up duration was 42.1 months for all patients. Propensity score matching successfully balanced the two groups with 29 patients matched to each group. The 3-year overall survival (OS), progression-free survival (PFS) and local control (LC) rates in the C-ion RT vs TACE groups were 75.9% vs 45.4%, 44.8% vs 16.1% and 85.2% vs 23.2%, respectively. The C-ion RT group showed better OS (hazard ratio [HR], 0.578 [95% confidence interval (CI): 0.295-1.132]; P = 0.106), PFS (HR, 0.460 [95% CI: 0.254-0.835]; P = 0.009) and LC (HR, 0.155 [95% CI: 0.062-0.390]; P < 0.001) than the TACE group. Multivariate analysis indicated that C-ion RT was significantly associated with increased PFS (HR, 0.562 [95% CI: 0.341-0.926]; P = 0.024) and LC (HR, 0.282 [95% CI: 0.150-0.528]; P < 0.001). C-ion RT provided better OS, PFS and LC than TACE in patients with solitary HCC >3 cm. This study indicated that C-ion RT is a possible alternative to TACE, which is the standard of care for patients with medium-to-large-sized HCCs.

This study is aimed to clarify the effectiveness of the image-rotation technique and zooming augmentation to improve the accuracy of the deep learning (DL)-based dose conversion from pencil beam (PB) to Monte Carlo (MC) in proton beam therapy (PBT). We adapted 85 patients with head and neck cancers. The patient dataset was randomly divided into 101 plans (334 beams) for training/validation and 11 plans (34 beams) for testing. Further, we trained a DL model that inputs a computed tomography (CT) image and the PB dose in a single-proton field and outputs the MC dose, applying the image-rotation technique and zooming augmentation. We evaluated the DL-based dose conversion accuracy in a single-proton field. The average γ-passing rates (a criterion of 3%/3 mm) were 80.6 ± 6.6% for the PB dose, 87.6 ± 6.0% for the baseline model, 92.1 ± 4.7% for the image-rotation model, and 93.0 ± 5.2% for the data-augmentation model, respectively. Moreover, the average range differences for R90 were - 1.5 ± 3.6% in the PB dose, 0.2 ± 2.3% in the baseline model, -0.5 ± 1.2% in the image-rotation model, and - 0.5 ± 1.1% in the data-augmentation model, respectively. The doses as well as ranges were improved by the image-rotation technique and zooming augmentation. The image-rotation technique and zooming augmentation greatly improved the DL-based dose conversion accuracy from the PB to the MC. These techniques can be powerful tools for improving the DL-based dose calculation accuracy in PBT.

Exposure to diagnostic and therapeutic radiation introduces risks for development of diseases later in life by causing DNA damage in cells. Currently, there is no clinical method for determining exposure risk caused by radiation toxicity to DNA. Cell-free DNA (cfDNA), a marker of DNA damage, is currently used to assess risk for long-term effects following organ transplantation, surgery and inflammation. The goal of our proposed study is to develop cfDNA as an early biomarker for assessing risk for cardiovascular disease and cancer from radiation exposure so that strategies to mitigate the damaging effects of medical radiation can be assessed. Hearts from male and female WAG/RijCmcr rats (n = 6-10/group) were exposed to increasing doses of X-radiation (50 mGy and 3.5 Gy). Blood was collected prior to and after (15 minutes-96 hours) irradiation, and cell-free plasma was prepared. Primers and probes were designed for quantitative analysis of sequences of mitochondria (12S rRNA) and nuclear (Gapdh) cfDNA present in rat plasma using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Exposure of hearts to radiation increased nuclear and mitochondrial cfDNA in a dose-dependent manner. Three point five grays from X-radiation increase cfDNA for Gapdh in plasma after 1 hour with a 15.8-fold increase (P < 0.001) after 6 hours. The earliest time nuclear and mitochondrial cfDNA increases were detected in plasma was at 60 minutes following exposure to 3.5 Gy. cfDNA has potential to advance as a biomarker of exposure to medical doses of radiation in patients.

The purpose of this study was to investigate the utilization and implementation of stereotactic body radiotherapy (SBRT) and intensity-modulated radiotherapy (IMRT) in Japan up to 2023. The survey was conducted by the Japanese Society for Radiation Oncology High-Precision External Beam Radiotherapy Group Subcommittee from December 2023 to February 2024. The study targeted patients treated with IMRT or SBRT between January 2021 and December 2022. A comprehensive web-based questionnaire was distributed to 880 facilities, with separate sections for radiation oncologists and medical physicists/radiotherapy technologists. A total of 360 facilities responded (response rate: 40.9%) for the section of radiation oncologists, and 405 facilities responded (response rate: 46.0%) for medical physicists/radiotherapy technologists, providing data on the implementation status, techniques, workload and challenges associated with IMRT and SBRT. Based on the responses in the section of radiation oncologists, IMRT was used in 68.6% of responding institutes, and SBRT in 87.8%. VMAT emerged as the most common IMRT technique (78.3%). The survey highlighted a high demand for medical physicists to perform IMRT (86.9%). Based on the responses in the section of medical physicists/radiotherapy technologists, 84.6% of the facilities that have not performed IMRT reported that the main reason was a lack of radiation oncologists. Furthermore, the survey also noted significant variations in prescribed doses and margin sizes across facilities, indicating the need for further standardization. High-precision radiation techniques such as IMRT and SBRT are getting popular, however, the facility requirements which mandate the presence of at least two radiation oncologists prevents IMRT from becoming more widespread in Japan.

The present study investigated risk factors and bronchial dose constraints for symptomatic radiation pneumonitis (RP) in stereotactic body radiotherapy (SBRT) for central early-stage non-small cell lung cancer (NSCLC). We reviewed 245 patients with early-stage NSCLC treated with SBRT, and 78 patients with a tumor within 3 cm of the main or lobar bronchus were included in this study. Dose-volume histogram data were converted to a 4-fraction equivalent using the linear-quadratic model with an α/β value of 3. To examine the independent effects of dose parameters on grade ≥ 2 RP after adjusting for clinical factors, the Fine-Gray model with death as a competing risk was used for evaluation. With a median follow-up period of 44 months, the 4-year cumulative incidence of grade ≥ 2 and ≥ 3 RP was 22.5% and 8.5%, respectively. After adjustment for clinical factors, 6 bronchial dosimetric factors were significantly associated with grade ≥ 2 RP. Lung dosimetric factors were not significantly associated with grade ≥ 2 RP. Among significant dosimetric factors of the bronchus, bronchus V35Gy had the highest hazard ratio (HR) (HR 1.24, 95% CI 1.03-1.49, P = 0.027). The optimal threshold for bronchus V35Gy based on receiver operating characteristic curve analysis was 0.04 cc. The 4-year incidence of grade ≥ 2 RP in the bronchus V35Gy ≤ 0.04 cc vs. >0.04 cc groups was 15.7% vs. 37.0% (P = 0.036). In SBRT for central early-stage NSCLC, bronchus V35Gy < 0.04 cc is the definitive indicator for preventing grade ≥ 2 RP.

Due to the limited number of accelerator-based X-ray facilities worldwide that provide beams with an adjustable size, their application for radiobiological research purposes has been restricted. Thus, the development of alternative methods is of technical importance for investigating cell/tissue responses in spatially non-uniform radiation fields. In this study, we performed mini beam irradiation of cells using a lead (Pb) sub-milli-collimator as an alternative method to sub-millimeter beams. Also, we employed human cervical carcinoma HeLa cells and hTERT-immortalized fibroblast BJ-1 cells that express fluorescence ubiquitination-based cell-cycle indicators (FUCCI). Time-lapse imaging revealed differences in the behavior of HeLa and BJ-1 cells in spatially heterogeneous radiation fields; in the case of HeLa cells, G2/M phase-arrested cells in the cell population were clearly observed, distinguishing irradiated from non-irradiated cells at the sub-millimeter scale level. Our findings indicate that FUCCI can be useful as a biological dose indicator, depending on cell type, and Pb sub-milli-collimators show potential as a possible alternative to accelerator-based X-ray sub-millimeter beams for radiobiological research. The use of the collimators, unlike beamtime experiments in synchrotron facilities with the approval of the committee, is highly versatile and may be beneficial in preliminary studies in a normal laboratory environment.

This study aims to create a deep learning-based classification model for cervical cancer biopsy before and during radiotherapy, visualize the results on whole slide images (WSIs), and explore the clinical significance of obtained features. This study included 95 patients with cervical cancer who received radiotherapy between April 2013 and December 2020. Hematoxylin-eosin stained biopsies were digitized to WSIs and divided into small tiles. Our model adopted the feature extractor of DenseNet121 and the classifier of the support vector machine. About 12 400 tiles were used for training the model and 6000 tiles for testing. The model performance was assessed on a per-tile and per-WSI basis. The resultant probability was defined as radiotherapy status probability (RSP) and its color map was visualized on WSIs. Survival analysis was performed to examine the clinical significance of the RSP. In the test set, the trained model had an area under the receiver operating characteristic curve of 0.76 per-tile and 0.95 per-WSI. In visualization, the model focused on viable tumor components and stroma in tumor biopsies. While survival analysis failed to show the prognostic impact of RSP during treatment, cases with low RSP at diagnosis had prolonged overall survival compared to those with high RSP (P = 0.045). In conclusion, we successfully developed a model to classify biopsies before and during radiotherapy and visualized the result on slide images. Low RSP cases before treatment had a better prognosis, suggesting that tumor morphologic features obtained using the model may be useful for predicting prognosis.