Journal of Radiation Research最新文献

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.

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.

Objective: To retrospectively analyze outcomes of patients who received definitive pelvic irradiation for clinically pelvic node-positive (cT1-4N1M0) prostate cancer (PCa).

Materials and methods: Clinical records of 148 patients with cT1-4N1M0 PCa treated with definitive pelvic radiotherapy (RT) between 2011 and 2015 were retrospectively collected from 25 institutions by the Japanese Radiation Oncology Study Group. The median age, initial prostate-specific antigen (PSA) level, and biologically effective dose (BED) to the prostate with α/β of 1.5 Gy were 69 (interquartile range [IQR], 65-74.3) years, 41.5 (IQR, 20.3-89) ng/ml, and 177.3 (IQR, 163.3-182) Gy, respectively. All patients underwent neoadjuvant androgen-deprivation therapy (ADT) for a median duration of 10 months. Most patients (141; 95.2%) received concurrent ADT during the irradiation period. The median duration of adjuvant ADT was 16 (IQR, 5-27.8) months. The Phoenix definition was used to assess biochemical failure.

Results: The median follow-up period was 53.5 months (IQR, 41-69.3). The 5-year overall survival (OS) probability was 86.8%. The 5-year biochemical failure-free survival and clinical progression-free survival rates were 69.6% and 76.3%, respectively. Multivariate analysis indicated the BED to the prostate to be a significant prognostic factor for OS. Regarding late adverse events, the estimated cumulative incidences of late Grade 2 or higher gastrointestinal and genitourinary toxicities at 5 years were 8.2% and 5.8%, respectively.

Conclusion: Long-term ADT combined with definitive pelvic external beam RT for cT1-4N1M0 PCa leaded to favorable outcomes. Future prospective studies should validate the suggested survival benefit of local dose escalation to the prostate in this cohort.

Accelerated partial breast irradiation (APBI) is an alternative treatment for early-stage breast cancer. This study aimed to evaluate the effectiveness of the virtual bolus (VB) method and robust planning against respiratory motion in volumetric modulated arc therapy (VMAT)-APBI. VMAT plans were generated with 30 Gy in 5 fractions for 16 patients. Four treatment plans were developed and compared: a standard optimization (SO) plan without robust methods, a pseudo-skin flash strategy using a 5 mm VB (with densities of 0.4 and 1.0 g/cm3, VB04 and VB10), and a robust optimization (RO) plan to minimize penalties in worst-case scenarios. The isocenter was shifted 1-5 mm in each translational direction in robust analysis, and perturbed dose calculations were performed. All dose constraints for the target in SO and VB plans were within acceptable limits, but the dose evaluation volume V95% in the RO plan was lower than in other plans (P < 0.05). The clinical target volume V95% of the RO plan was significantly higher than in VB04 and VB10 (P < 0.05). The RO plan showed the best performance for organs at risk, followed by SO and VB plans, which resulted in higher doses. The RO plan exhibited the smallest change (±2%) in dose distribution due to respiratory motion. By contrast, the SO plan lacked robustness owing to absence of sufficient fluence in the air surrounding the planning target volume outside of the skin surface. The RO plan offers superior target coverage, maximum dose, and robustness compared to SO and VB methods.

This study aimed to investigate the safety of combining radium-223 chloride (Ra-223) therapy with external beam radiation therapy (EBRT) for patients with multiple bone metastases from castration-resistant prostate cancer (CRPC), including lesions requiring urgent treatment such as those causing neurological symptoms due to spinal cord compression. We retrospectively analyzed data from patients with CRPC and bone metastases treated with Ra-223 therapy at our hospital between September 1, 2018, and December 31, 2023. Adverse events were evaluated using the Common Terminology Criteria for Adverse Events version 4.0. Of the 23 patients referred, data from 17 were included; 8 received concurrent Ra-223 therapy and EBRT, whereas others received only Ra-223 therapy. The median follow-up period was 20 months. Grade (G) 2 or higher adverse events occurred in seven patients (41.2%), and G 3 or higher in 2 (11.7%). None of the patients who received EBRT with fields involving the gastrointestinal tract experienced diarrhea, constipation, bleeding, perforation, or obstruction. Ra-223 therapy with EBRT did not increase adverse events compared with studies of Ra-223 therapy without EBRT. One case of G 5 Pneumocystis carinii pneumonia, likely because of steroid use for neurological symptoms and the patient's underlying diabetes mellitus, was noted. The effects of EBRT cannot be entirely excluded, so minimizing field size and dose is recommended when combining Ra-223 therapy and EBRT. Our findings indicate that concurrent Ra-223 therapy and EBRT could be safe for managing patients with symptomatic bone metastases and castration-resistant prostate cancer who require specialized treatment, provided sufficient attention is given to the field and the prescribed dose.

This study aimed to evaluate the prognostic value of pre-treatment blood cell counts in patients with brain metastasis (BM) from non-small cell lung cancer (NSCLC) who were treated using linear accelerator (linac)-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator. Between January 2011 and November 2022, 271 consecutive patients underwent linac-based SRS/fSRT for BM from NSCLC. Thirty patients with insufficient blood test data during this period were excluded from this analysis. Thirty-five patients with steroid intake at the time point of the blood test and 18 patients with higher C-reactive protein were excluded. Thus, 188 patients were eventually enrolled in this study. The median follow-up period after SRS/fSRT was 21 months (range: 0-121 months), and the median survival time after SRS/fSRT was 19 months. Neutrophil-lymphocyte ratio ≥ 1.90, lymphocyte-monocyte ratio ≤ 1.67 and systemic inflammation response index (SIRI) ≥ 2.95 were unfavorable predictors of prognosis for patients who underwent SRS/fSRT for BM from NSCLC. Cox proportional-hazard multivariate analysis revealed that the SIRI was independent prognostic factors for increased risk of death. Thus, simple, less expensive, and routinely performed pre-treatment blood cell count measurements such as SIRI can predict the overall survival of patients treated with SRS/fSRT for BM from NSCLC.

Postoperative chemoradiotherapy (POCRT) is the standard treatment for patients with head and neck squamous cell carcinoma (HNSCC) with high-risk features (positive microscopic margins and/or extranodal extensions). We hypothesized that dose escalation using hyperfractionation in intensity-modulated radiotherapy (HF-IMRT) improves POCRT outcomes; however, no prospective trial has assessed the feasibility of POCRT in HF. Therefore, we evaluated the feasibility of POCRT using HF-IMRT. HNSCC patients with positive microscopic margins and/or extranodal extension following surgery were included. HF-IMRT (73.6 Gy in 64 fractions twice daily) was administered along with cisplatin at 40 mg/m2 once a week for seven cycles during radiotherapy. The primary endpoint was the proportion of patients who completed treatment, which included the planned radiotherapy and the administration of ≥200 mg/m2 of cisplatin. Feasibility was defined as the proportion of patients who completed treatment >60% using a one-sided binomial test. Ten patients were registered between October 2021 and April 2023. One patient was excluded because of tumor recurrence before POCRT. The median follow-up time was 18.2 months, and the proportion of patients who completed treatment was 88.9%. The median total dose of cisplatin was 240 mg/m2. The percentage of patients with grade 3 acute non-hematological adverse events was 77.8%. No patient experienced grade 4 or higher acute adverse events or grade 3 or higher late adverse events. POCRT using HF-IMRT is feasible for achieving adequate cisplatin doses and safe radiotherapy in patients with HNSCC.