To investigate whether converging electron beams using quadrupole electromagnets can mitigate fluence loss and bremsstrahlung contamination in small irradiation fields. Approach: A three-stage quadrupole electromagnet system was installed beneath a linear accelerator head to converge 6, 9, 12, and 15 MeV electron beams. Dose distributions, dose rate, and bremsstrahlung contamination were evaluated for 2 cm and 1 cm fields. The 2 cm convergent field was compared with a 2 cm tubular applicator, whereas the 1 cm convergent field was evaluated at 5.1 and 10 cm air gaps. Monte Carlo simulations at 6 and 9 MeV assessed detector volume-averaging effects and the origins of bremsstrahlung photons. Main results: The dose rate of the 2 cm convergent field was 1.05-2.53 times higher than that of the 2 cm tubular applicator, while bremsstrahlung contamination was reduced by 0.40-1.79 percentage points. The 1 cm convergent field achieved a therapeutic field width ≤1 cm and penumbra ≤0.85 cm at all energies. At a 5.1 cm air gap, the dose rate was comparable to that of a 3 cm tubular applicator at 9 MeV and exceeded that of a 10 × 10 cm[2] applicator at 12 and 15 MeV. Bremsstrahlung contamination was 1.08%, 0.87%, 1.04%, and 1.32% at 6, 9, 12, and 15 MeV, respectively, and remained lower than that of the 2 cm tubular applicator at all energies. At a 10 cm air gap, output decreased and dose profiles broadened. Bremsstrahlung contamination increased to 2.56%, 1.70%, 1.72%, and 2.11%, respectively, but remained lower than that of the 2 cm tubular applicator at 12 MeV and above. Significance: Converging electron beams can mitigate fluence loss while reducing bremsstrahlung contamination in small fields. This externally mounted system provides proof of concept for high-spatial-resolution electron beam delivery and future electromagnetic spot-scanning applications.

Accuracy in dose delivery in brachytherapy treatments is a critical component for clinical success and patient safety, requiring a rigorous quality assurance system. The implementation of external dosimetric audits plays a fundamental role in verifying the planned and delivered doses, allowing the identification of discrepancies that could compromise tumor control or increase toxicity in healthy tissues, as well as ensuring compliance with national and international recommendations and standards. This work presents the development and validation of a methodology for external auditing in high-dose-rate (HDR) brachytherapy using an Ir-192 source, conducted within the scope of a research project coordinated by the International Atomic Energy Agency (IAEA), with the participation of nine countries. A positioning phantom, manufactured through 3D printing, was designed to accommodate various models of intracavitary applicators, allowing adaptable and reproducible assembly conditions for dosimetric evaluation. Optically Stimulated Luminescence (OSL) dosimeters (nanoDot model) were used for point dose measurements around the applicator, in configurations previously standardized based on the results obtained from earlier tests leading to the final prototype. The coordinates of these points were registered in the Treatment Planning System (TPS) and used as a reference for experimental comparison, respecting distances and depths equivalent to those defined in the planning. The applied methodology allowed the comparison between the experimental data obtained with NanoDot OSL dosimeters and the doses calculated by the TPS. The dosimeters were positioned in a cross-shaped configuration around the applicator, maintaining a distance of 2 cm from the ring and 2 cm from the probe (tandem), ensuring a standardized and reproducible geometric arrangement. The project was funded by project E24023, International Atomic Energy Agency (IAEA), Contract number 24544.

Background/Objectives: Cutaneous squamous cell carcinoma (cSCC) treated with high-dose-rate (HDR) surface brachytherapy using patient-specific 3D-printed applicators lacks a validated non-invasive follow-up modality capable of resolving microscopic residual disease. Line-field confocal optical coherence tomography (LC-OCT) provides real-time, cellular resolution, three-dimensional imaging of the epidermis and superficial dermis and has been proposed as a candidate tool for post-radiotherapy monitoring. We evaluated the feasibility of LC-OCT for pre- and post-treatment imaging of cSCC and assessed whether an LC-OCT-defined remission phenotype, operationally defined a priori as the absence of all malignancy-associated LC-OCT criteria, can be documented after 3D-printed HDR surface brachytherapy. Methods: Eight consecutive patients with histologically confirmed cSCC, unsuitable for surgery, were treated with HDR surface brachytherapy delivered through patient-specific 3D-printed applicators. LC-OCT imaging was performed immediately before brachytherapy and at short-term follow-up (six months). Nineteen pre-treatment LC-OCT criteria derived from the Cinotti 2021 descriptive criterion set for cSCC were scored: seventeen malignancy-associated criteria, plus elastosis (scored as a background photodamage covariate, not counted towards remission) and fibrosis (scored post-treatment only). Presence/absence of each criterion was rated by two blinded dermatologists; inter-assessor agreement was quantified using percentage agreement and Cohen's kappa. Results: Baseline LC-OCT showed a rich malignant signature: hyperkeratosis, parakeratosis, disarranged epidermal architecture, dyskeratotic keratinocytes, atypical and crowded nuclei, and dermoepidermal junction alterations were present in eight out of eight lesions (100%) under an inclusive two-reader rule. At short-term follow-up, six months after the final brachytherapy fraction, all seventeen malignancy-associated criteria constituting the pre-specified remission set were absent in all eight patients under the decision rule described in the article-which classifies isolated dilated linear vessels occurring in an otherwise criterion-negative, fibrotic dermis as post-radiation telangiectasia rather than residual tumour, yielding an LC-OCT-defined remission phenotype rate of 100% (eight out of eight; 95% exact binomial [Clopper-Pearson] CI 63.1-100%). Post-radiation fibrosis was observed in 8/8 patients (100%), and dilated linear vessels were observed in six out of eight patients (75%, evaluated under the same decision rule (Observer 1: 4/8; Observer 2: 6/8). Elastosis, a marker of background actinic photodamage present in eight out of eight lesions at baseline and excluded from the malignancy-associated criterion count, is distinct from post-treatment fibrosis, a radiation-induced dermal remodelling feature scored only at follow-up; the two should not be conflated. Conclusions: In this proof-of-concept cohort, LC-OCT was feasible for pre- and post-treatment imaging of cSCC after 3D-printed HDR surface brachytherapy, produced highly reproducible dual-observer readings (κ = 0.903), and documented, at a single short-term time point six months after the final fraction, an LC-OCT-defined remission phenotype in every treated lesion, with a consistent fibrosis signature. Persistent dilated linear vessels in a fibrotic, otherwise criterion-negative dermis were classified as a non-specific post-radiation vascular change and did not preclude LC-OCT-defined complete remission. Because this remission phenotype rests on a pre-specified but not externally validated imaging definition and was not anchored to post-treatment histopathology or reflectance confocal microscopy, it constitutes an imaging surrogate rather than a confirmed complete remission, and microscopic residual disease below the resolution limit of LC-OCT cannot be excluded. These hypothesis-generating findings support LC-OCT as a candidate non-invasive monitoring modality, requiring confirmation in larger, biopsy-anchored prospective studies with longer follow-up.

This study investigated the feasibility and reproducibility of inverse planning (IP) in gynecologic high-dose-rate brachytherapy (BT) across ten institutions (five IP and five manual). Two pre-defined cases (high-risk clinical target volume, CTVHR: 62.8 and 27.4 cm3) included the organs at risk (OARs), a tandem, ovoids, and 8 and 3 interstitial needles, respectively. Each institution generated BT plans according to its policy, assuming 30 Gy/15 fractions of whole-pelvis irradiation and 20 Gy/10 fractions of central shielding. Plans were evaluated using dose-volume histogram (DVH) parameters. Dwell-time distributions were compared with conventional Manchester-based pear-shaped plans to identify deviations (e.g. needle dominance and high-dose characteristics) that may not be captured by DVH alone. Institutional interviews assessed clinical acceptability and optimization strategies. All plans were considered clinically acceptable, with no significant differences between IP and non-IP groups in CTVHR D90% and OARs ${{D}}_{{2}\ {\mathrm{cm}}^{{3}}}$. IP institutions used institution-specific strategies to preserve uterine dose conformity, including fixing dwell times for selected applicators and applying optimization constraints based on Manchester-derived contours, delineated ovoids or delineated uterine structures. Overall, IP plans were comparable to non-IP plans for CTVHR D90%, CTVHR V100% (cm3) and OARs ${{D}}_{{2}\ {\mathrm{cm}}^{{3}}}$. In contrast, differences in dose distribution around the uterine fundus and the wide range of the body V100% (cm3) suggested varying institutional strategies for fundus dose. These findings highlight the need for planning QA that incorporates dwell-time review in addition to DVH parameters, and provide a foundation for optimizing and standardizing IP in gynecologic BT to improve planning reproducibility and patient outcomes.

Background: In-office dental bleaching is a common aesthetic procedure, and different application methods may influence laboratory and clinical outcomes. Objectives: This systematic review and meta-analysis evaluated the effects of applicator brush use compared with conventional application without a brush during in-office hydrogen peroxide bleaching. Methods: The review followed PRISMA guidelines and was registered in PROSPERO (CRD42023491451). Electronic searches were conducted in PubMed, Cochrane Library, LILACS, and OpenGrey for studies published until April 2026. Clinical and in vitro studies comparing bleaching gel application with and without an applicator brush were included. Outcomes included hydrogen peroxide concentration in the pulp chamber, bleaching gel consumption, color change, and tooth sensitivity. Risk of bias was assessed using RoB 2 for the randomized clinical trial and the Sarkis-Onofre tool for in vitro studies. Meta-analyses were performed using RevMan, and certainty of evidence was assessed using the GRADE approach. Results: Of 10,260 records identified, four studies met the eligibility criteria, including one randomized clinical trial and three in vitro studies. Quantitative synthesis was based exclusively on the three in vitro studies. The randomized clinical trial showed low risk of bias, whereas the in vitro studies presented methodological limitations. Meta-analyses showed no statistically significant differences between applicator brush and conventional application methods for hydrogen peroxide concentration in the pulp chamber or bleaching gel consumption, although pooled estimates showed a tendency toward lower values with applicator brush use. No significant differences were observed in color change outcomes assessed by ΔEab, ΔE00, or ΔWID (p > 0.05). Heterogeneity ranged from 0% to 99%, and the certainty of evidence for all outcomes was rated as very low. Conclusions: Based on predominantly laboratory evidence of very low certainty, applicator brush use may be associated with lower hydrogen peroxide concentration in the pulp chamber and reduced bleaching gel consumption; however, these findings should be interpreted cautiously, and the clinical relevance of this application method remains uncertain.

The accuracy of dose calculation algorithms significantly influences brachytherapy treatment outcomes. TG-43 algorithm has been widely adopted due to its simplicity, which has standardized contemporary brachytherapy dose calculations worldwide. However, TG-43's homogeneity assumption potentially compromises clinical treatment accuracy. The present study aimed to investigate TG-43 accuracy against Monte Carlo (MC) simulation. Varian GammaMed Plus [192]Ir High-dose-rate (HDR) brachytherapy source was modeled using TOPAS3.9 MC simulation-framework. Three well-defined test scenarios were examined: Homogeneous water phantom, TG-186 generic-applicator, and computed-tomography (CT) based intracavitary brachytherapy (ICBT) patient plan. Corresponding TG-43 based treatment plans were generated using Eclipse BrachyVision and imported into TOPAS for MC-simulation. Both TG-43 and MC dose distributions were evaluated using point-dose assessment, dose-volume metrics, dose-volume histogram, and γ-analysis with 2% Dose-difference and 1 mm Distance-to-agreement. In a homogeneous water phantom, TG-43 and MC exhibited close agreement, with dose-difference (Δ%) at the reference point and for High-risk clinical target volume (HRCTV) found to be below 1-3% and γ-passing rates ≥95%. However, in the presence of a TG-186 applicator, TG-43 substantially overestimated doses by 60-93% on shielded side and 4-13% on unshielded side. For CT-based ICBT patient plan, TG-43 overestimated HRCTV and organ-at-risk (OAR) doses relative to MC. The mean γ-passing rate in clinical ICBT plan was 90%, indicating moderate spatial agreement. Present study validated the accuracy of TG-43 algorithm against MC simulation confirming its adequacy in homogeneous phantom. However, significant deviations were observed in the presence of an applicator, and tissue heterogeneity revealed TG-43 limitations. TG-43 consistently overestimates dose owing to the homogeneity assumption. These findings emphasize the necessity of adopting Model-based calculation algorithms such as MC to improve the dosimetric precision and treatment accuracy in HDR brachytherapy.

Peach gummosis, caused primarily by Botryosphaeria dothidea sensu lato, is a destructive canker disease with few environmentally friendly management options. Here we report an uncontrolled pre/post field demonstration of a γ-polyglutamic acid-based artificial biofilm - a biodegradable delivery platform whose agent-agnostic design remains untested - encapsulating Bacillus amyloliquefaciens KNU-28 across 143 trees in 18 commercial peach orchards in South Korea. Severity declined from a pre-treatment mean of 4.12 (April) to 2.32 by August (76.2% of 143 trees improved by ≥1 point) and to 1.78 by October in three regions (88.3% of 128 trees). In an ordinal cumulative-link mixed model, severity fell below the April baseline at every later visit; the average monthly odds ratio was 0.70 (95% CI 0.66-0.75); alternative model specifications agreed. Operator-independent image-based ΔE quantification across 74 trees showed a concordant cohort-level decline (lesion-area declines of 19-30%; significant in one of four regions after FDR correction) but agreed only weakly with the ordinal score at tree level (Spearman ρ = 0.16), and is complementary rather than confirmatory. We sequenced fungal ITS2 from 23 bark samples. Multivariate dispersion differed among bark groups (PERMDISP F = 20.7, p < 0.001), and healthy and gummosis-affected bark did not separate under compositionally aware metrics (Aitchison/robust CLR, p > 0.34); the nominally significant Bray-Curtis PERMANOVA (R2 = 0.248, p = 0.001) therefore cannot be read as a centroid difference. Early- and later-treatment diseased communities did not differ (p = 0.542; all genera FDR q > 0.5). Gummosis-enrolled bark showed higher relative abundances of Wickerhamomyces, Cytospora and Botryosphaeria (dominant ASVs assigned to B. qingyuanensis) than healthy bark, though none survived FDR correction. Because the 19 diseased libraries came from only 10 trees, the genus-severity correlations were replaced by a paired analysis, in which no genus differed nominally. Together, this demonstration establishes the operational feasibility of field-scale application and a parameter-transparent lesion-quantification method; the severity decline and mycobiota trends are accompanying observations. Because untreated controls, strain-level KNU-28 tracking, verification of delivery to bark and a powered microbiome cohort were absent, the data do not establish causal efficacy and warrant randomized, untreated-control trials.