Journal of Radiation Research最新文献

An optical fiber-based neutron detector is a real-time neutron monitor for an intense neutron field. A small piece of neutron scintillator, such as Ce-doped lithium glass (Li-glass), used in the detector has a random shape with a grain size of 200-400 μm. This causes shape-dependent effects on the detector response. However, it is difficult to control or determine its shape due to its small size. Here we propose a technique to characterize the fine structure of a small piece of scintillator using a microcomputed tomography (CT) system. To verify accuracy, the mass calculated based on the density of Li-glass and the volume extracted from the obtained CT image was compared to the mass measured in advance using an electronic balance. In the obtained CT images, the fine shape of the small piece of Li-glass was clearly visible, and no false signals from the surrounding components were observed. The calculated mass was in good agreement with the measured value, however, when the total number of projection images was 2000, a slight underestimation was observed. This was mitigated by increasing the number of projection images, and the difference between the calculated and measured mass was 1.6% when the number of the projection images was 3141. This was equivalent to the uncertainty of the measured mass. The proposed technique will be useful when high accuracy is needed, such as for medical applications.

Lymphopenia during chemoradiotherapy (CRT) for glioblastoma has been shown to be a poor prognostic factor. However, the relationship between prolonged lymphopenia (PL) after CRT and prognosis remains unclear. This study aimed to explore the relationship between PL and glioblastoma prognosis and develop a predictive model for PL risk. We analyzed 87 patients with primary glioblastoma who underwent postoperative CRT with 60 Gy in 30 fractions of radiotherapy and temozolomide. PL was defined as grade 2 or higher lymphopenia 1 month after the completion of CRT. We conducted survival analysis, identified risk factors for PL, and developed a predictive model for PL risk. Of the 87 patients, 41 developed PL, and progression-free survival (PFS) was significantly shorter in the PL group (median 8.0 months vs 15.4 months, P = 0.003). However, there was no significant difference in overall survival between the two groups. PL was also a significant factor for shorter PFS in multivariable analysis (P = 0.040). Brain V20Gy (percentage of brain volume receiving ≥20 Gy), gross total resection (GTR), and preoperative Karnofsky performance status (KPS) were identified as significant risk factors for PL. The predictive model showed that the risk of PL could be predicted by brain V20Gy, sex, age, GTR and preoperative KPS. PL was identified as a PFS shortening factor. Our model suggests that reducing irradiated brain volume may help prevent PL and could potentially improve glioblastoma prognosis by preserving cancer immunity.

This study aimed to compare and verify the rectal and bladder doses of intracavitary brachytherapy (ICBT) using both rectal retractor (RR) and gauze packing (GP) in the same patients. A total of 37 patients who underwent ICBT using RR and GP for cervical cancer were included in this study. Rectal and bladder dose and volume data were compared with the RR and GP treatments in the same patients and the confounding factors were examined. When comparing RR and GP, the median and interquartile ranges for rectal D2cc were 2.8 (2.5-3.7) Gy with RR and 3.2 (2.7-3.8) Gy with GP. The median bladder D2cc was 4.9 (4.5-6.3) Gy with RR and 4.8 (3.9-5.4) Gy with GP. The Wilcoxon signed-rank test revealed that rectal doses were significantly lower with RR (P = 0.02), whereas bladder doses were significantly higher with RR (P < 0.001). Analysis of the correlation between the number of gauze pieces and the difference in rectal D2cc between GP and RR using Pearson's distribution revealed no significant correlation (R = -0.20, P = 0.22), as well as bladder D2cc between GP and RR also revealed no significant correlation (R = -0.20, P = 0.22). The number of gauze pieces did not necessarily correlate with a reduction in the rectal and bladder dose. In conclusion, rectal D2cc was lower with RR in image-guided brachytherapy for cervical cancer, whereas bladder D2cc was higher with RR than with GP.

This study aimed to analyze the clinical outcomes and prognostic factors of postoperative adjuvant radiotherapy (RT) for vulvar cancer based on a retrospective Japanese nationwide survey. Data were collected from 108 institutions for patients diagnosed with vulvar cancer between January 2001 and December 2010. Patients with histologically confirmed squamous cell carcinoma, adenocarcinoma, or adenosquamous carcinoma who underwent curative surgery and adjuvant radiotherapy were included in this study. Survival outcomes were estimated using the Kaplan-Meier method, and prognostic factors were analyzed via univariate and multivariate models. A total of 139 patients were included, with a median follow-up of 44 months (range: 3-169). The 5-year overall survival (OS) rates (95% confidence interval [CI]) for stages I, II, III, and IV were 71.8% (50.8-92.8%), 61.3% (40.1-82.5%), 58.0% (45.8-70.2%), and 47.3% (27.5-67.1%), respectively. The corresponding 5-year cause-specific survival (CSS) rates (95% CI) for stages I, II, III, and IV were 71.8% (50.8-92.8%), 73.4% (53.0-93.8%), 62.2% (50.0-74.4%), and 47.3% (27.5-67.1%). Multivariate analysis identified age ≥70 years as an independent adverse prognostic factor for OS (hazard ratio [HR]: 1.848; 95% CI: 1.039-3.281; P = 0.042), while the presence of ≥2 inguinofemoral lymph node metastases was significantly associated with poorer CSS (HR: 2.179; 95% CI: 1.109-4.280; P = 0.030). Our analysis identified advanced age and a higher nodal burden as significant predictors of poorer survival outcomes in patients with vulvar cancer receiving postoperative adjuvant RT.

Despite the environmental significance of airborne particulates generated from mine tailings, there is limited information on exposure of people living in the neighbourhoods adjacent to such sites. The main objective of the study was to assess cancer risk due to enhanced radionuclides present in dust samples and to evaluate the exposure risk of populations living in three mining areas in the Free State and West Rand in South Africa. Soil and dust samples were collected between January 2016 and March 2018 in different seasons for determination of the level of naturally occurring radioactive materials in the samples. The samples were prepared and sealed for 4 weeks to attain secular equilibrium of the 238U and 232Th and their respective progenies, and thereafter analysed using gamma spectroscopy. Radiological parameters were calculated from the activity of the radionuclides to estimate exposure risk. The absorbed dose rate in air ranged from 76 to 137, 50 to 133 and 19 to 75 (nGy hr-1) for areas A, B and C, respectively. The mean excess lifetime cancer risk in all three mines was lower than the world average of 1.45 × 10-3; accordingly, the cancer risk was found to be negligible. The findings revealed that most radiological parameters were within the accepted international values; thus the soils in the areas could be considered to be safe for the humans living there.

The influences of tumor volume and total radiation dose on pain relief outcomes have not been fully investigated. We investigated potential correlations between gross tumor volume (GTV), biologically effective dose (BED) and pain relief in patients receiving radiation therapy (RT) for painful tumors. As a secondary analysis of a three-center prospective observational study of 302 patients who received RT for painful tumors, patients treated at an academic hospital were analyzed. We used the Brief Pain Inventory short form to evaluate pain intensity and interference in patients' lives. We collected the Brief Pain Inventory and analgesic data at baseline and 1, 2, 3, 6, 9 and 12 months after the start of RT. Pain responses were assessed using the International Consensus Endpoint. The Fine and Gray models were used for univariable and multivariable analyses, to estimate the impact of clinical factors on pain response and pain progression. In total, 153 (59%) of the 258 patients experienced a pain response, and 45 (17%) patients experienced pain progression. In the univariable and multivariable analyses, GTV and BED did not significantly associate with pain response or pain progression. Furthermore, no significant interaction between GTV and BED was reported in terms of pain response or pain progression after adjusting for covariates. The impact of BED on pain response and pain progression did not vary according to the GTV.

There are no reports on shrinkage of multiple hepatocellular carcinomas (HCCs) after simultaneous treatment with radiotherapy. The purpose of the study was to examine the relationship between tumor shrinkage and treatment outcomes for several HCCs irradiated simultaneously using proton beam therapy (PBT). The subjects were 46 patients with multiple HCCs (95 lesions) who received PBT between January 2008 and December 2018. Overall survival (OS), local control (LC) and complete+partial response (CR + PR) rates were determined using the Kaplan-Meier method. The median follow-up period was 29.2 months and the 3-year OS was 50.3%. For the 95 lesions, the 3-year LC rate was 90.4% and the CR + PR rate was 85.2% at 3 years. Three combination protocols (referred to as A, B and C) were used for different lesions in the same patient: A (66 Gray (Gy) Relative biological effectiveness (RBE) in 10 fractions (fr))-B (72.6 Gy(RBE) in 22 fr) (22 lesions), A-C (74 Gy(RBE) in 37 fr) (15 lesions) and B-C (2 lesions). The 1-year CR + PR rates were 75.8% for A and 56.4% for B in A-B cases (P = 0.14), and 62.5% for A and 57.1% for C in A-C cases (P = 0.35). In the B-C group, there was only one patient with 2 lesions. The lesion treated with the B protocol reached CR + PR, while that treated with the C protocol did not reach CR + PR. These results show that some cases can have differences in tumor shrinkage after concurrent PBT for multiple HCCs, and that there is no significant relationship between dose and tumor shrinkage.

Stereotactic body radiation therapy (SBRT) has emerged as a promising and minimally invasive treatment option for patients with renal cell carcinoma (RCC). This study presents our initial clinical experiences with treatments following our center's protocol, which was formulated based on both national and international evidence. Six patients who had undergone renal SBRT at our center from January 2021 to December 2023 were included. Treatment planning used computed tomography (CT) and magnetic resonance imaging, with respiratory management conducted through breath-hold or free-breathing techniques. The prescribed dose was primarily 48 Gy in three fractions, with increased fractionations when dose constraints were challenging to achieve. Dose constraints were met for all patients, and treatment planning adhered to protocol guidelines. After the confirmation of cone-beam CT (CBCT) images by physicians, radiation was delivered. Five out of six patients completed the planned treatment, whereas one discontinued the treatment midway (the causal relationship to radiation therapy was unclear). Dose-volume histogram analysis revealed that doses to organs at risk depended on the position and size of the planning target volume but remained within acceptable limits for all cases. The intrafractional patient motion was 2.7 mm, as calculated from the pre- and post-CBCT images, confirming the appropriateness of a 3-mm setup margin. Although this study provides initial insights, further clinical trials are warranted to establish standardized protocols and optimize treatment strategies for RCC. In the future, it is also necessary to generate evidence that is tailored to the current situation in Japan.

This study addresses the escalating radiation safety concerns among medical professionals due to the rising application of proton and carbon ion radiotherapy. It evaluates the occupational radiation exposure faced by therapists when utilizing the Siemens IONTRIS Proton-Carbon Ion System. Through random sampling of 80 patients treated between January and June 2024, we recorded particle types and counts and measured dose rates using a photon/neutron radiation dose meter. Notably, 1 min post-treatment, the dose rate peaked at 16.00 μSv/h near the tumor's skin surface, showing a significant correlation with particle count. The therapist's standing position and the surfaces of the range shifter and ripple filter registered average dose rates of 1.25 μSv/h and 3.63 μSv/h, 0.33 μSv/h, respectively. Other points averaged 0.08 μSv/h, with no neutron detection. The study concludes that the annual average occupational exposure for therapists, at ~300 μSv, is significantly below the International Commission on Radiological Protection's recommended dose equivalent limit, confirming the safety of the Siemens IONTRIS device in clinical settings.

Adult T-cell lymphoma/leukemia (ATL) is an aggressively malignant peripheral T-cell neoplasm. Only a few studies have reported the use of radiotherapy (RT) for ATL. Therefore, the aim of this study was to clarify the efficacy of RT for ATL. We retrospectively reviewed 90 courses of RT administered to 19 consecutive ATL patients between 2008 and 2023. The subtypes included lymphoma (n = 8), acute (n = 7), smoldering (n = 3) and unknown (n = 1). Ninety lesions (cutaneous = 72, extranodal = 10, nodal = 8) were treated at a mean dose of 39.1 Gy/3.2 Gy (range, 24-60 Gy). Administration of RT for ATL lesions resulted in a combined complete response and partial response rate of 92%. At a mean of 47.5 months of follow-up (range, 0-102 months), local recurrence was not observed in 98.9% of the courses. A treatment response in terms of clinical symptoms was observed in 92% of the courses. The median survival time was 918 days. No acute grade ≥3 toxicity or any late toxicity was noted. In conclusion, RT was confirmed to be effective and safe for the treatment of local ATL lesions.