Image-guided passive scattering proton therapy (PSPT) has been widely adopted in Japan and worldwide, with substantial long-term clinical data supporting its efficacy in treating prostate cancer. However, as hypofractionated protocols become increasingly common, the impact of internal anatomical shifts on surrounding organs at risk (OARs) warrants renewed attention. The pubic bones, situated near the prostate, are often exposed to unintended high doses, especially during internal error correction based on fiducial marker alignment. This study retrospectively analyzed 30 patients with localized prostate cancer treated with PSPT using lateral opposed fields. Simulated isocenter shifts were applied anteriorly and inferiorly in 2-mm increments up to 10 mm to assess dose changes to the pubic bones. Dose-volume histogram metrics including V80%, V90% and V95% were evaluated. Pubic bones dose increased in both shift directions, with a more pronounced effect for anterior shifts, with a 10-mm anterior shift increasing V80% by 14.2 cc on average-2.4 times greater than inferior shifts. Dose elevation correlated strongly with the anatomical proximity between the clinical target volume and pubic bones (r > 0.66, P < 0.001). These results suggest that anterior correction in PSPT can cause substantial dose escalation to the pubic bones, potentially increasing the risk of insufficiency fractures. As extreme hypofractionation becomes more common, careful evaluation of pubic bones dose should be incorporated into treatment planning, alongside traditional OARs such as the rectum and bladder. Early replanning should be considered when persistent anterior displacement is observed to maintain patient safety and quality of life.

This study presented a quantitative analysis of the differences in the depths of the distal 50% of acquired and estimated positron emission tomography (PET) images for 18 patients who had a total of 109 titanium (Ti) metal-surgical clips implanted after breast-conserving surgery. Offline PET/computed tomography (PET/CT) images were acquired after proton irradiation. Hounsfield Unit modifications were applied to correct for metal artifacts induced by the Ti clips in the planning CT scans of the soft tissues surrounding the clips. The positron-emitting-isotope PET distribution was calculated through Range-Verification scripting. Quantitative analysis was conducted on the depth differences at the distal 50% R50 of the PET and the calculated PET distribution. Using the R50 method, the depth verification results of the clips and the normal tissues were compared. The R50 method calculates the positional difference at the half-maximum value 2 cm from the skin, with clips beyond this position not affecting the results. Analyses of the regions around the Ti clips were conducted. The depth difference for Ti < 2 cm (where the depth of the clips from the skin was <2 cm) was -1.63 ± 1.08 mm, while the corresponding normal tissue (Ticont) showed a depth difference of -1.79 ± 1.15 mm. There was no statistically significant difference in the depth differences between Ti < 2 cm and the corresponding Ticont. This study utilized offline PET verification to demonstrate that applying tissue corrections based on surgical clips and surrounding muscle tissues in clinical practice ensures that the presence of surgical clips does not compromise the precision of proton dose delivery at the surgical site.

This study evaluates current practices and challenges associated with computed tomography number-to-mass density (CT-MD) conversion tables in helical tomotherapy across Japan and explores directions for standardization and quality improvement amid the increasing adoption of adaptive radiotherapy (ART). A nationwide web-based survey was conducted across 34 institutions utilizing the Radixact system. Data were collected on CT acquisition protocols, calibration phantoms, density plugs, reconstruction algorithms, table registration timing and quality assurance (QA) frequency. Registered CT-MD tables were categorized by CT modality: Simulation CT (SimCT), ClearRT and CTrue. ClearRT tables were analyzed by phantom setup (full vs half), and CTrue tables by reconstruction method [filtered back projection (FPB) vs iterative reconstruction (IR)]. Inter-institutional variations in CT numbers and the number of data points were assessed. SimCT tables exhibited the widest variation in the number of data points (median = 10) and high-density CT numbers. ClearRT tables (median = 8) showed variations of up to 300 Hounsfield units (HU) in cortical bone; the half-phantom setup reduced inter-institutional variability. CTrue tables (median = 8) demonstrated high consistency, with negligible differences between IR and FPB. All plug CT numbers of CTrue remained within the tolerance defined by the American Association of Physicists in Medicine Task Group 148. However, CT numbers for air plugs varied by ~±30 HU, indicating inconsistent handling of air reference values. Additionally, 43% of institutions did not perform routine QA. Standardizing phantom geometry, air CT number handling and QA protocols-particularly using half-phantom calibration-may improve CT-MD table consistency and dose accuracy in ART.

Helical tomotherapy-based total body irradiation (TBI) traditionally employs megavoltage computed tomography (MVCT) for image-guided setup; however, its 390 mm field of view (FOV) and long acquisition times constrain workflow efficiency and whole-body alignment. This study evaluated whether a newly implemented whole-body fan-beam kilovoltage CT (kVCT; 500 mm FOV) can streamline this process. In a retrospective study involving 14 patients treated with a Radixact X9 system (September 2021-September 2023), we timed the patient setup, imaging, registration, re-setup, and beam delivery for each upper-body (UB) and lower-body (LB) segment. Residual setup errors were measured along the lateral, longitudinal, and vertical axes. The kVCT shortened the initial setup cycle (setup + imaging + registration) from 25.4 ± 4.6 to 15.9 ± 3.3 min for UB and from 14.5 ± 3.8 to 9.4 ± 2.4 min for LB (P < 0.001 for both). The total fraction time, including delivery time, decreased from 71.8 ± 7.5 to 56.7 ± 5.3 min. When residual errors exceeded 5 mm, the additional time required for a second cycle was nearly halved with kVCT (7.3 vs. 14.3 min for UB; 4.8 vs. 8.2 min for LB). The kVCT maintained mean absolute residual errors below 2 mm in all axes, and every 95th-percentile value remained within the 5 mm tolerance recommended for tomotherapy-based TBI. These time savings are expected to reduce intrafraction motion and staff workload. Overall, whole-body kVCT enables faster, comprehensive image guidance while preserving accuracy, thereby streamlining tomotherapy-based TBI and reducing the burden on patients and clinical staff.

Spacers separating the tumor from adjacent organs help improve irradiation dose parameters. We introduce a new hyaluronate gel spacer with MEIJI (ADANT®) as an alternative to the previously used Suvenyl® and its injection technique for cervical cancer brachytherapy. Five patients with cervical cancer underwent hyaluronate gel injection (HGI) with the MEIJI hyaluronate gel in their rectovaginal and vesicovaginal septa. The minimum doses covering 90% of the high-risk clinical target volume (CTVHRD90%), the most exposed 2 cc (D2cc) of organs at risk per session, as well as the total doses for combined external beam radiotherapy (with a central shield) and brachytherapy, were assessed. The median CTVHRD90% was 9.3 (range, 6.4-9.7) Gy per session and 92.2 Gy in the equivalent dose in 2 Gy fractions (EQD2) (80.3-93.3 Gy-EQD2) overall. The median rectum D2cc was 2.9 (1.8-5.0) Gy per session and 45.4 (43.4-57.1) Gy-EQD2 overall. The median D2cc of the bladder (bladder D2cc) was 4.8 (2.4-6.5) Gy per session and 64.6 (62.3-69.6) Gy-EQD2 overall. The MEIJI spacer disappeared within 3 or 7 days with no adverse events associated with HGI or deterioration of the patients' quality of life. MEIJI HGI facilitates a sufficient CTVHRD90% while keeping the rectal and bladder D2cc within dose constraints, even when the rectum and bladder are in close proximity to the CTVHR. In conclusion, the MEIJI spacer may help appropriately meet dose constraints, thereby potentially contributing to improving local control and/or reducing adverse events for patients receiving radiotherapy for cervical cancer.

4-Borono-L-phenylalanine (BPA) is a key 10B carrier used in boron neutron capture therapy (BNCT), while its PET tracer analogue, 4-borono-2-18F-fluoro-L-phenylalanine (18F-BPA), enables non-invasive visualization of tumour boron uptake. Since BNCT efficacy depends on precise tumour boron accumulation, we evaluated whether 18F-BPA mirrors BPA's transport and biodistribution. In vitro, BPA exhibited a highly consistent uptake profile with its non-radioactive fluorinated analogue, 2-19F-4-borono-L-phenylalanine (19F-BPA), across nine cancer cell lines (r = 0.9455, P < 0.001) and tri-iodothyronine (T3)-mediated LAT-1 inhibition markedly reduced the uptake of both BPA and 19F-BPA. In vivo, BPA and 18F-BPA showed predominant accumulation in the kidneys and pancreas in Sprague-Dawley rats, with substantially lower levels detected in other organs. Importantly, in tumour-bearing mice, the time-concentration curve of BPA and the time-activity curve of 18F-BPA in tumours were found to be highly consistent, and showed a corresponding relationship between BPA concentration and 18F-BPA activity in terms of accumulation in tumour, blood, and muscle (r = 0.9623, P < 0.0001). Collectively, these findings confirm that BPA and 18F-BPA not only share LAT-1-mediated transport mechanisms, but also exhibit similar pharmacokinetics and tumour-specific accumulation. This substantiates the use of 18F-BPA as a reliable surrogate for visualizing BPA biodistribution and optimizing patient-specific BNCT treatment planning.

This study aimed to evaluate the radioprotective effects of melatonin on healthy thyroid and laryngeal tissues exposed to head and neck radiotherapy using flattening filter (FF) and flattening filter-free (FFF) radiotherapy beams. Forty-eight female Wistar albino rats were randomly assigned to five groups (n = 8): control, only melatonin, FF, FF + melatonin, FFF and FFF + melatonin. A single 16 Gy dose of radiation was delivered to the head and neck region using a linear accelerator. Melatonin (50 mg/kg) was administered intraperitoneally 15 minutes prior to irradiation. Biochemical parameters including malondialdehyde (MDA), myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were measured from serum samples. Histopathological evaluations of thyroid (inflammation, epithelial hyperplasia, follicular hyperplasia, C-cell hyperplasia, cellular degeneration, follicular cell hypertrophy and cellular necrosis) and laryngeal (general morphological deterioration, inflammation, oedema, epithelial destruction, karyorrhexis and karyolysis) tissues were performed using a semi-quantitative scoring system. FF and FFF beam exposure significantly increased MDA and MPO levels while reducing antioxidant enzyme activities (SOD, CAT, GPx) compared to the control group (P < 0.05). Histologically, both radiation types induced marked inflammation, cellular damage and morphological degeneration in thyroid and laryngeal tissues. Melatonin administration significantly reversed these effects, improving antioxidant enzyme levels and mitigating tissue damage (P < 0.05). No statistically significant difference was observed between FF and FFF groups in either biochemical or histological outcomes. FF and FFF beams produced comparable levels of oxidative and structural damage in healthy tissues. Melatonin demonstrated significant radioprotective effects through both biochemical and histopathological pathways, suggesting its potential role in mitigating radiotherapy-induced toxicity in non-target tissues.

Quad Shot (QS) is effective in treating head and neck cancer; however, few prospective studies have been conducted in this direction. Further, no studies have investigated tumor pain and stomatitis pain separately. We prospectively investigated the efficacy and adverse events of QS in 11 patients with head and neck cancer who underwent QS at our hospital in Japan between 2018 and 2024. The QS method involved administering 3.7 Gy twice daily for 2 days, which was considered one course and provided thrice at an interval of 4 weeks. We assessed quality of life (QOL) scores, albumin levels, and numerical rating scale (NRS) scores for stomatitis and tumor pain before and after QS to evaluate changes in NRS. Eleven patients with advanced head and neck cancer received QS treatment: six patients underwent three courses, three underwent two, and two underwent one. There was no significant difference in QOL scores before and after QS, but albumin levels dropped significantly after QS. NRS due to stomatitis significantly worsened after QS, whereas NRS due to tumor significantly improved. Tumor size decreased and tumor NRS improved as the QS treatment duration increased. However, stomatitis was almost always present, and NRS scores for stomatitis increased significantly after treatment. In conclusion, QS can alleviate tumor pain but may worsen stomatitis. Therefore, stomatitis care should be emphasized during treatment. Furthermore, the decrease in albumin levels is likely due to stomatitis-induced decreased appetite; therefore, stomatitis management is also important for maintaining nutritional status.

Investigation on tritium (3H) washout process in a tropical region at Kakrapar Atomic Power Station (KAPS), Gujarat, India was carried out. 3H concentration in air as well as that in rainwater is estimated near KAPS Site having Pressurized Heavy Water Reactors (PHWRs) operational. Samples were collected covering the four rainy seasons from 2016 to 2019. The corresponding meteorological parameters of relative humidity, ambient temperature, wind speed, wind direction, and atmospheric stability were measured. The rain spectral characteristics such as raindrop diameter, fall velocity, liquid water content (LWC) in raindrops and average rain rate are also studied. Site-specific wet deposition rate (Bq m-2 s-1) and washout coefficient for 3H (s-1) is observed to be in the range of 1.4E-05 to 4.8E-01 (Geometric Mean = 5.3E-03) and 1.1E-07 to 3.6E-02 (Geometric Mean = 4.1E-05) respectively. Significant and positive correlation was observed between average rain rate and washout coefficient (R2 = 0.73). Significant and negative correlation was observed between raindrop diameter of different rain events and 3H activity in rainwater (R2 = 0.70).

Since 2018, the staging system and guidelines for cervical cancer have been revised in Japan. Here, we analyzed trends in radiotherapy use among patients with cervical cancer in Osaka Prefecture, Japan. We obtained records from hospital-based cancer registries (2016-23) linked to Diagnosis Procedure Combination data (2019-23), from 67 nationally or prefecturally designated cancer care hospitals. Eligible patients had epithelial or neuroendocrine cervical cancer, excluding those with clinical stage 0 or unknown clinical stage with pathological stage 0. Between 2016 and 2023, the number of patients per year remained stable (717-787); the number of stage IB-IIA (FIGO 2018) cases decreased, whereas that of stages IIB or IIIC (T1-2) cases increased. The number of patients receiving radiotherapy as initial treatment increased from 229 in 2016 to 294 in 2023; this was accompanied by a decline in surgical treatment. The proportion of patients undergoing radiotherapy increased from 11.9% to 17.2% for stage IB-IIA, from 55.6% to 71.7% for stage IIB and from 38.0% to 69.5% for stage IIIC (T1-2). Among 11 institutions providing brachytherapy, the number of radiotherapy cases increased at three, whereas it remained stable or declined at the other eight. These findings indicate a growing trend in radiotherapy use for cervical cancer in Osaka Prefecture; however, the increase varied by institution. To sustain cervical cancer radiotherapy services, further studies may be needed to assess the adequacy of brachytherapy staffing, explore the financial feasibility of brachytherapy equipment, and examine the potential implications of brachytherapy centralization.

From simple viruses to complex multicellular animals, ionizing radiation can have deleterious effects on all organisms. For humans, exposure to radiation can come from a wide range of sources such as environmental contamination, occupational hazards, radiotherapy and space flight. In the next few decades, radiation toxicity will become an increasing healthcare concern as nuclear power usage, risk of nuclear war, space-based industry and cancer incidence are all projected to increase. While the biology of acute radiation sickness is relatively well understood, ionizing radiation can also cause severe chronic effects whose molecular and cellular basis remain largely a mystery. This is partly because complications that arise months or even years after exposure depend on tissue-level responses, and so there are aspects of late radiation toxicity that can only be investigated in vivo. We suggest that Drosophila melanogaster can contribute to understanding this phenomenon. To this date, Drosophila radiation research has been heterogenous in terms of dose, radiation type and developmental stage of exposure, but despite this a pattern of observations suggest that fruit flies experience both short- and long-term radiation injury. Moreover, the genetic underpinning of the Drosophila radiation response seems conserved with that of humans. We propose that Drosophila is well-suited to model radiation damage to tissues, highlighting the potential of the fly to inform clinical radiobiology research.

Total neoadjuvant therapy (TNT) improves oncological outcomes in locally advanced rectal cancer (LARC); however, treatment-induced lymphopenia remains a concern. We analyzed 74 patients undergoing three TNT regimens: long-course chemoradiotherapy with consolidation chemotherapy (LCCRT-CNCT), short-course radiotherapy with CNCT (SCRT-CNCT), and induction chemotherapy with LCCRT (INCT-LCCRT). Severe radiation-induced lymphopenia (RIL, Grade ≥ 3) occurred in 48%, 24%, and 54%, respectively (P = 0.126). In the LCCRT-CNCT group, large bowel irradiation (V35 Gy > 46 cc) was significantly associated with severe RIL in univariable analysis but not in multivariable models (P = 0.227), and in an exploratory combined analysis of LCCRT-CNCT and INCT-LCCRT, this showed a trend (P = 0.093). Pre-TNT absolute lymphocyte count (ALC) was an independent predictor of RIL. Small bowel irradiation (V15 Gy > 104 cc) predicted severe lymphopenia during chemotherapy in the univariable analysis; but multivariable analysis suggested pre-TNT ALC as the main factor, showing a trend toward significance (P = 0.051). In the SCRT-CNCT group, pre-TNT ALC was the only significant factor for severe lymphopenia in both the RT and chemotherapy phases in univariable analysis. Severe RIL significantly prolonged lymphocyte recovery time (median, 283 vs. 76 days, P < 0.001), whereas immune recovery did not differ according to the TNT regimen. The median ALC at the last follow-up was 86% of the baseline value, indicating incomplete recovery. While pre-TNT ALC correlated with lymphopenia risk, minimizing bowel irradiation may help mitigate treatment-induced immunosuppression. Prospective studies are required to validate these findings.

The objective of this study was to establish guidelines for evaluating the health effects of electromagnetic fields (EMFs). To achieve this, a comprehensive evaluation of EMF effects on living organisms from both engineering and biological perspectives is essential. As part of this study, we examined the impact of intermediate-frequency magnetic fields (IF-MF) exposure on peripheral nerves in mice and validated the reliability of five pain assessment methods. The engineering approach was based on our pilot study, while the biological approach involved exposing mice to IF-MF for a 28-day period and assessing neurotoxicity through the implementation of five pain tests. The von Frey test, conducted with a Dynamic Plantar Aesthesiometer, was performed at various time points during exposure. The results indicated that leg withdrawal time was shortened only in the positive control group. After conducting a series of assessments, we demonstrated that no statistically significant differences were observed among the IF-MF-exposed, sham-exposed and control groups. However, the positive control group exhibited significant variations in the four supplemental assessments. No significant differences were detected in the other three groups. These findings suggest that subacute (28-day) IF-MF exposure at 2.3 times the basic restriction for occupational exposure according to International Commission on Non-Ionizing Radiation Protection guideline does not result in peripheral neurotoxicity and that the utilized pain assessment methods used for IF-MF exposure are effective.

Radiation exposure is a significant risk factor for various tumors and illnesses, with early-stage radiation dose closely linked to disease progression. Accurate assessment of radiation exposure is critical for effective treatment. This study aimed to identify radiation-induced DNA damage repair-related genes using weighted gene co-expression network analysis on datasets GSE90909 and GSE102971, supplemented by literature. A protein-protein interaction network was constructed to identify key genes, and their expression levels were compared between irradiated and control groups to evaluate diagnostic efficacy. Immune-related scores were calculated, and correlations between diagnostic genes and immune cells were analyzed. Regulatory networks involving transcription factors (TFs), microRNAs (miRNAs) and key genes were established, alongside gene interaction networks using GeneMANIA. A gene-drug interaction network was also developed. Five key genes-PCNA, REV3L, POLH, LIG1 and XPC-were identified, all significantly overexpressed in irradiated populations. These genes demonstrated strong diagnostic capability for radiation exposure and were positively correlated with radiation dose. Their expression levels were also closely associated with immune cell infiltration, including natural killer cells, plasma cell-like dendritic cells and regulatory T cells. Key regulatory interactions involved TFs (E2F1, TP53) and miRNAs (miR-145, miR-143), while associated genes included FEN1, REV1 and CDKN1A. Drugs linked to these genes included Quercetin and Hydroxyurea. In conclusion, the study identified five key genes with diagnostic potential for radiation exposure, positively correlated with radiation dose. These findings provide a foundation for radiation diagnosis and dose assessment, particularly in populations with later-stage diseases.

This survey was conducted to examine the real-world practice of definitive chemoradiotherapy (CRT) for locally advanced non-small cell lung cancer (LA-NSCLC) in Japan, aiming to standardize treatment, reduce inter-institutional disparities and identify areas for future research. A questionnaire was sent to members of the Japanese Radiation Oncology Study Group through a mailing list, with responses collected between December 15, 2023, and March 14, 2024. Responses from 112 institutions revealed that 81.2% either did not set general upper age limits or established limits at 80 years or older for definitive CRT in LA-NSCLC. The most common absolute contraindications were active interstitial pneumonia (60.7%) and contralateral hilar lymph node metastasis (42.0%). Relative contraindications involved dose-volume indices of the normal lung (70.5%). The most commonly adopted dose-volume indices were lung V20Gy < 30%, lung V5Gy < 60% and mean lung dose <20 Gy, while no definite indices were established for heart V50Gy and mean heart dose in half of the institutions. Additionally, 88.4% of institutions reported using IMRT for LA-NSCLC. Involved-field radiotherapy (IFRT) was adopted regardless of institutional size, and institutions with higher IMRT usage for LA-NSCLC also had higher IFRT adoption rates. In conclusion, this nationwide survey revealed the expanded use of definitive CRT and a growing emphasis on reducing lung dose to mitigate pulmonary toxicities, facilitated by advancements in IMRT and IFRT. Regularly conducting these surveys is essential to monitor evolving treatment strategies.

We investigated toxicity and patient-reported outcomes in patients with localized prostate cancer treated with moderately hypofractionated radiotherapy, focusing on clinically meaningful deterioration assessed using the minimum clinically important difference (MCID) at 24 months. Between January 2019 and December 2021, 58 patients were prospectively enrolled at a single institution and received volumetric-modulated arc therapy and image-guided radiotherapy, delivering 60 Gy in 20 fractions. The median follow-up period was 48 months. Toxicities were evaluated using the Common Terminology Criteria for Adverse Events version 5.0. Health-related quality of life (HR-QOL) was assessed at baseline and at 3, 6, 12, 24 and 36 months using the Short Form-8 Health Survey (SF-8) and the Expanded Prostate Cancer Index Composite (EPIC). Grade 2 acute gastrointestinal (GI) and genitourinary (GU) toxicities occurred in 0% and 5.2% of patients, respectively. Late Grade 2 GI and GU toxicities occurred in 1.7% and 6.9% of patients, respectively. No Grade ≥ 3 toxicities were reported. At 24 months, a ≥ 2 × MCID decline in SF-8 physical and mental component scores was observed in 12.2% (95% confidence interval [CI]: 3.2-21.2%) and 14.3% (95% CI: 4.5-24.1%), respectively. In the EPIC domains, ≥ 2 × MCID declines occurred in 23.8% (95% CI: 10.9-36.7%) for bowel and 8.5% (95% CI: 0.5-16.5%) for urinary summary scores. A 60 Gy regimen delivered in 20 fractions is feasible and well tolerated, with low toxicity and stable HR-QOL, although these preliminary findings are based on a limited observation period and sample size. Longer follow-up and larger studies are warranted.

Boron Neutron Capture Therapy (BNCT) is a targeted radiotherapy that utilizes the nuclear reaction of 10B with thermal neutrons to destroy tumor cells while sparing healthy tissue. Its effectiveness relies on accurately modeling boron distribution. Current treatment planning systems use a fixed tumor-to-normal tissue (T/N) boron ratio, ignoring pharmacokinetics. This study improves BNCT dose calculations by integrating time-dependent boron concentrations from pharmacokinetic simulations. Firstly, this research improved the traditional two-compartment pharmacokinetic model to a three-compartment model to better represent boron distribution, accounting for different tumor locations. Two patient cases were simulated, and the comparisons were performed between the dose distributions obtained by the fixed T/N ratio method and the ones obtained by our pharmacokinetic-based approach. Results showed significant discrepancies between the two methods, with the maximum dose deviation in the tumor region reaching 11.386%. The pharmacokinetic-based method provided more accurate and individualized dose calculations. Secondly, the multi-objective optimization using the Basin Hopping algorithm was employed to determine the optimal irradiation time periods. This approach enhanced treatment efficacy by increasing the average dose and maximum dose in the gross tumor volume by ~4% within the same irradiation period, while minimizing damage to normal tissues. The optimized irradiation schedules resulted in improved dose delivery to the tumor while maintaining safe levels for normal tissues. Our findings highlight the importance of integrating pharmacokinetic data into BNCT treatment planning to improve dose accuracy and treatment outcomes.

In recent years, there has been growing interest in cardiac toxicity following radiation therapy (RT) for esophageal cancer; however, detailed incidence and risk factors in Japanese patients remain unclear. The purpose of this study was to clarify the incidence, timing, risk factors, and dose-volume relationships of multiple cardiac toxicities, including pericardial effusion, heart failure, arrhythmia, cardiac valve disease and acute coronary syndrome. We retrospectively analyzed patients of thoracic esophageal cancer without distant metastasis who were treated with curative RT at our hospital between 2007 and 2020. Cardiac toxicity events were graded according to common terminology criteria for adverse events v5.0. Association between cardiac dose-volume parameters and grade 2 or higher toxicity was analyzed using logistic regression analysis. The analysis included 250 patients, with a median follow-up period of 21 months. The 2-year cumulative incidence of grade 2 or higher pericardial effusion, heart failure, arrhythmia, and acute coronary syndrome were 36.6%, 0.4%, 1.4%, and 1.3%, respectively. Logistic regression analysis identified the volume of the whole heart receiving 30Gy as a significant risk factor for grade 2 pericardial effusion (OR, 1.03; 95% confidence interval [CI], 1.01-1.04; P < 0.01) and grade 2 arrhythmia (OR, 1.10; 95%CI, 1.02-1.18; P = 0.01). We reported detailed profile of cardiac toxicity in Japanese patients who received curative RT for esophageal cancer. Reducing cardiac radiation dose may reduce the risk of pericardial effusion and arrhythmia.

Two chemical dosimeters, lithium formate monohydride (LFM) and L-alanine (ALA), were first evaluated under ultra-high dose rate (UHDR) proton irradiation conditions, known as 'FLASH', which has the potential to reduce the impact on normal tissue while effectively killing tumors, using electron spin resonance (ESR) spectroscopy. Both ALA and LFM demonstrated a significant linear increase in ESR peaks that correlated with the physical dose when comparing conventional radiation (CONV) to UHDR radiation. The relative effectiveness (RE: the ratio of the amount of free radicals produced by each type of proton irradiation to the amount produced by 60Co γ-ray irradiation) was determined for CONV, UHDR-Plateau and UHDR-Peak, yielding RE values of 0.849, 0.731 and 0.661 for LFM and 0.834, 0.692 and 0.624 for ALA, respectively. The decrease in RE values was likely due to the combination of UHDR and the increase of linear energy transfer (LET) to facilitate the recombination of radicals formed within the crystal during CONV and UHDR of proton beams. When using the height of the ESR central peak as an indicator of sensitivity, LFM was assessed to be ~20% more sensitive than ALA.

This study evaluated the impact of off-center diagonal (OCD) profile depth pairing between the treatment planning system (TPS) and the electronic portal imaging device (EPID) on gamma pass rates in portal dosimetry. In clinical workflows, OCD profiles are used in the TPS to generate predicted images via the portal dosimetry image prediction (PDIP) algorithm and in the EPID system to correct measured fluence. The consistency of these settings may influence verification accuracy. Portal images were acquired using a TrueBeam linear accelerator with an aS1200 EPID for four photon energies: 6X, 10X, 6 flattening filter-free (FFF) and 10FFF. Five OCD profiles (reference depth, 5, 10, 20 and 30 cm) were configured in both the PDIP model and EPID system. For each energy, a total of 175 plan-measurement combinations were evaluated, derived from five PDIP OCD depths combined with five EPID OCD depths across seven field sizes. Field sizes ranged from 5 × 5 to 30 × 30 cm2. Gamma analysis used 3%/3 mm criteria with a 10% dose threshold. A two-way analysis of variance assessed the effects of TPS and EPID OCD depths and their interaction. For 6X and 10X beams, pass rates varied with configuration, showing better agreement when depths were matched or EPID was deeper. In contrast, 6FFF and 10FFF beams maintained high pass rates with minimal variation. These findings indicate that OCD depth pairing influences portal dosimetry performance, particularly for flattened beams, underscoring the importance of depth-aware configuration in QA protocols.