Radiation and Environmental Biophysics最新文献

{"title":"Influence of single and co-doped lanthanides on the thermoluminescence response of hydroxyapatite prepared by the hydrothermal method.","authors":"Hamideh Daneshvar","doi":"10.1007/s00411-026-01259-y","DOIUrl":"https://doi.org/10.1007/s00411-026-01259-y","url":null,"abstract":"<p><p>In this study, nanostructured hydroxyapatite (HAp) doped with lanthanide elements (Ce, Dy, Gd, and La at various concentrations of 1, 2, and 5 mol%) was synthesized by a hydrothermal method to evaluate its potential for high-dose radiation dosimetry. X-ray diffraction (XRD) analysis confirmed the formation of a pure hydroxyapatite phase in all samples with no detectable secondary phases, indicating successful dopant incorporation. Thermoluminescence (TL) measurements were performed after ⁶⁰ Co gamma irradiation over a wide dose range of 20-3,000 Gy. The results showed that TL sensitivity is strongly dependent on dopant type and concentration; notably, 1 and 2 mol% Ce and Dy exhibited the highest sensitivities, while 5 mol% samples showed concentration quenching. The glow curves revealed prominent peaks, indicating good thermal stability and suitability for dosimetric applications. Kinetic parameters including activation energy (E) and frequency factor(s) were determined using Chen's peak-shape method, showing that Ce1, Ce2, and Gd5 samples follow first-order kinetics, which is favourable for dosimetric applications, as the glow peak maximum temperature ([Formula: see text]) remains independent of the absorbed dose. The TL behaviour of co-doped systems (Ce2Dy2, Ce2La2, La2Dy2, and Ce2Gd5) was also investigated. While co-doping altered the glow-peak structure and dosimetric properties, it generally exhibited an intermediate dosimetric performance between the corresponding single-doped constituents rather than a distinct synergistic enhancement. The co-doped compositions maintained higher TL sensitivity than the heavily quenched 5 mol% single-doped counterparts, though remaining below the optimum sensitivity achieved by 1-2 mol% single-doped samples. In addition, reproducibility tests over five irradiation-readout cycles showed acceptable stability, with relative standard deviations ranging from 3.6% for Gd2 to 13.2% for Ce2. Fading measurements also confirmed good signal retention, with the best co-doped sample retaining 86.5% of its TL response after 30 days. Overall, the high sensitivity, broad linear dose-response behaviour, with some compositions remaining linear up to 3,000 Gy, acceptable reproducibility, and favourable fading behaviour make Ce- and Gd-doped HAp promising candidates for environmental and industrial radiation dosimetry, while further low-dose investigations are required to assess their suitability for medical dosimetry.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149184166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monte Carlo evaluation of small-field output correction factors of a microDiamond detector in flattened and flattening-filter-free photon beams for stereotactic radiotherapy.","authors":"Hamza Sekkat, Oussama El Mouden, Abdellah Khallouqi, Youssef Madkouri, Abdellah Halimi, Omar El Rhazouani","doi":"10.1007/s00411-026-01260-5","DOIUrl":"https://doi.org/10.1007/s00411-026-01260-5","url":null,"abstract":"<p><p>Small-field dosimetry is clinically challenging because of volume averaging, loss of lateral charged-particle equilibrium, and beam-quality changes, especially for multi-leaf collimator (MLC)-defined fields and flattening-filter-free (FFF) beams. This study derived machine-specific IAEA TRS-483 output correction factors for a PTW 60,019 microDiamond detector on an Elekta Versa HD linac for 6 MV and 10 MV photons in both flattened filter (FF) and FFF modes, using square fields down to 1 × 1 cm². A detailed GATE/Geant4 Monte Carlo model of the treatment head (including the Agility MLC) was validated against 10 × 10 cm² percentage depth doses (PDDs) (mean absolute differences 0.20-0.29% points) and 1 × 1 cm² profiles (FWHM differences < 0.06 mm). Uncorrected MC-measurement output factor deviations at 1 × 1 cm² reached + 1.03% (6 MV), + 1.15% (10 MV), + 1.66% (6 MV FFF), and + 2.08% (10 MV FFF), but stayed ≤ 0.3% for fields ≥ 3 × 3 cm². Corresponding output correction factors at 1 × 1 cm² were 1.0103, 1.0115, 1.0166, and 1.0208, approaching unity (± 0.2%) for ≥ 5 × 5 cm². Agreement with TRS-483 reference tables was within 0.6% at 1 × 1 cm² and < 0.4% at 2 × 2 cm². Film and MicroSilicon checks agreed within 1-2% at 2 × 2 cm², but differed by 13-15% at 1 × 1 cm² for 10 MV, reinforcing the need for machine-specific factors, particularly for 1 × 1 cm² and FFF beams. These findings indicate that small-field detector correction should be regarded as specific to the treatment-unit, beam mode, and field configuration rather than as a universally transferable quantity. In clinical implementation, Monte Carlo-based correction should therefore be integrated with independent verification when dosimetry approaches the limits of detector and field-size resolution.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149184178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dosimetric impact of computational phantom selection in passive scattering proton therapy: Development and validation of an extended MIRD prostate phantom using Geant4 Monte Carlo simulation.","authors":"Mostafa Khosravi, Mohammad Torkiha, Daryoush Shahbazi-Gahrourei","doi":"10.1007/s00411-026-01261-4","DOIUrl":"https://doi.org/10.1007/s00411-026-01261-4","url":null,"abstract":"<p><p>Accurate anatomical modelling is important for reliable Monte Carlo (MC) proton dosimetry, yet the influence of computational phantom selection on clinically relevant dose prediction remains insufficiently quantified. In this study, an anatomically extended Medical Internal Radiation Dose (MIRD) computational phantom was developed for passive scattering proton therapy of prostate cancer and systematically compared with the anatomically realistic reference male phantom recommended by the International Commission on Radiological Protection using a validated Geant4 MC simulation framework. The extended phantom incorporated the prostate, bladder, rectum, urethra, and intraprostatic tumour volumes. At the same time, a clinical passive-scattering beamline at the CATANA proton therapy facility was modelled to generate spread-out Bragg peaks for treatment planning. The simulation framework demonstrated excellent agreement with experimental depth-dose measurements, yielding a practical proton range (R₉₀) deviation of 1.10 mm and a gamma passing rate of 98.63% under the 3%/2 mm criterion, confirming the accuracy of the dosimetric model. Following dose normalisation, both phantom models achieved identical target coverage (D₉₅=74 Gy) and conformity (CI = 0.95). In contrast, anatomical representation produced measurable differences in proton transport characteristics, including a 5.29% variation in proton range and a 72.4% difference in distal falloff. Quantitative dosimetric analysis further demonstrated differences in internal target dose distribution and organ-at-risk dose metrics despite comparable overall treatment quality, indicating that conventional target coverage indices alone do not fully reflect the dosimetric consequences of anatomical modelling. Although all evaluated organ-at-risk doses remained below commonly accepted clinical dose constraints, the observed variations in dose deposition highlight the sensitivity of proton transport to tissue geometry and heterogeneity. These findings suggest that computational phantom selection represents an important modelling factor influencing Monte Carlo proton dose prediction and that mathematically defined phantoms can provide a flexible platform for methodological and dosimetric investigations when their inherent anatomical simplifications are appropriately considered.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149172279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of different CBCT acquisition protocols on radiation dose and observer agreement in the assessment of impacted mandibular third molars.","authors":"Serhat Efeoglu, Hakan Eren, Rana Nalcaci","doi":"10.1007/s00411-026-01257-0","DOIUrl":"https://doi.org/10.1007/s00411-026-01257-0","url":null,"abstract":"<p><p>This study aimed to evaluate the effects of different CBCT (Cone-beam computed tomography) protocols defined by device type, field of view (FOV), and dose settings on organ-specific radiation doses and inter-/intra-observer agreement in the assessment of impacted mandibular third molars. A total of 168 CBCT scans (NewTom 7G and NewTom Go) were retrospectively analyzed. Each device included six protocols (different FOVs and dose levels: low, regular, best). Organ and effective doses were calculated using the Monte Carlo PCXMC 2.0 Rotation software. Three observers independently assessed five anatomical parameters related to surgical risk. Inter- and intra-observer agreement was analyzed using Fleiss' and Cohen's kappa. Effective doses ranged from 8.65 to 376.96 µSv, a more than 40-fold difference between the lowest- and highest-dose protocols. NewTom Go protocols with limited FOV and low/regular doses yielded the lowest effective doses without a corresponding loss of observer agreement. Observer agreement was substantial to almost perfect for most parameters (kappa: 0.541-0.915), although agreement for periodontal ligament visibility and root resorption was partly driven by shared \"not visible\"/\"uncertain\" ratings rather than confident structure identification. As no clinical or surgical reference standard was used, these findings reflect observer agreement and diagnostic interpretability rather than confirmed diagnostic accuracy. Limited FOV and optimized dose settings reduced radiation exposure while preserving observer agreement, supporting ALADAIP (As Low As Diagnostically Acceptable being Indication-oriented and Patient-specific) principles.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149169825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Updated dosimetric comparison of HDR interventional radiotherapy including ⁶⁰Co sources versus VMAT and electron beam therapy for NMSC.","authors":"Sidra Sajjad, Muhammad Shahban, Enrico Rosa, Bruno Fionda, Humera Mehmood, M Basim Kakakhel, Luca Tagliaferri, Marco De Spirito, Elisa Placidi","doi":"10.1007/s00411-026-01258-z","DOIUrl":"https://doi.org/10.1007/s00411-026-01258-z","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Non-melanoma skin cancers (NMSCs), primarily basal cell carcinoma and squamous cell carcinoma, are the most common malignancies worldwide and frequently arise on the scalp, where complex curvature and anatomical constraints make treatment planning challenging. While surgery remains the standard approach, radiotherapy, particularly high-dose-rate interventional radiotherapy (HDR-IRT, modern brachytherapy), has become an important alternative for patients who are not ideal surgical candidates. Previous dosimetric analyses have demonstrated that &lt;sup&gt;192&lt;/sup&gt;I HDR-IRT provides superior target coverage and dose conformity compared with external beam techniques such as volumetric modulated arc therapy (VMAT) and electron beam therapy (EBT). However, the reproducibility of these findings across centres and radioactive sources, including &lt;sup&gt;60&lt;/sup&gt;Co, has not been systematically validated. This study aimed to independently validate prior dosimetric results by independently replanning the same cohort of 25 patients with scalp NMSC using &lt;sup&gt;60&lt;/sup&gt;Co HDR-IRT. The objective was to assess whether the dosimetric advantages of HDR-IRT remain consistent when different operators, institutions, and isotopes are employed, and to compare &lt;sup&gt;60&lt;/sup&gt;Co HDR-IRT with VMAT and EBT under identical clinical conditions. A retrospective dosimetric comparison was conducted using the original CT datasets from 25 patients previously analyzed with &lt;sup&gt;192&lt;/sup&gt;Ir HDR-IRT. At an independent institution, new plans were generated for &lt;sup&gt;60&lt;/sup&gt;Co HDR-IRT, VMAT, and EBT using the same contours, applicator geometry, prescription doses, and V&lt;sub&gt;95%&lt;/sub&gt; constraints. HDR-IRT plans were constructed in Oncentra Brachy v4.6 based on TG-43 formalism; VMAT and EBT plans were generated in Eclipse TPS v16.1 using 6 MV photons and 6 MeV electrons, respectively. Dosimetric parameters (V&lt;sub&gt;90%&lt;/sub&gt;, V&lt;sub&gt;95%&lt;/sub&gt;, V&lt;sub&gt;100%&lt;/sub&gt;, D&lt;sub&gt;90%&lt;/sub&gt;, D&lt;sub&gt;mean&lt;/sub&gt;, D&lt;sub&gt;max&lt;/sub&gt;) and brain D2cc values were extracted from DVHs. Statistical comparisons were performed with the Mann-Whitney U test (p &lt; 0.05). All techniques provided comparable V&lt;sub&gt;90%&lt;/sub&gt; (&gt; 99%) and V&lt;sub&gt;95%&lt;/sub&gt; values, ensuring consistent baseline coverage. However, HDR-IRT using Co-60 demonstrated significantly higher V&lt;sub&gt;100%&lt;/sub&gt;, D&lt;sub&gt;90%&lt;/sub&gt;, and D&lt;sub&gt;mean&lt;/sub&gt; values than VMAT and EBT across all prescription groups (p &lt; 0.05). This reflects the proximity of the source to the target and the steep dose gradient inherent to brachytherapy. VMAT produced the most homogeneous dose distributions but at the expense of slightly reduced high-dose coverage. EBT performed adequately for small, flat lesions but showed pronounced limitations in large or curved anatomies, with increased variability and occasional hotspots in the brain. Brain D&lt;sub&gt;2cc&lt;/sub&gt; doses remained comparable across modalities (p &gt; 0.05), confirming adequate protection of critical structures. This external validation c","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monte Carlo analysis of depth dose distributions of ⁴He and ¹²C ion beams from 0.1 to 10 GeV in a human head phantom.","authors":"Alessandro Bartoloni, Mustafa Mohammad Rafiei, Lidia Strigari","doi":"10.1007/s00411-026-01249-0","DOIUrl":"https://doi.org/10.1007/s00411-026-01249-0","url":null,"abstract":"<p><p>Long-duration human spaceflight and crewed missions to the Moon and Mars - recently renewed priorities for several space agencies - pose major technical and biomedical challenges, including reliable supplies of oxygen, water, and food. Among the most critical is protecting astronaut health from intense fluxes of energetic charged particles in space. Measurements and numerical simulations are both used to study the interactions of these energetic particles with human tissues. In this work, the Monte Carlo codes FLUKA (v4-5.0) and Geant4 (v11.3.2) were used to simulate and analyze depth-dose distributions for monoenergetic ⁴He and ¹²C ions over a broad energy range (0.1, 0.25, 0.5, 1, 5, and 10 GeV) in the Snyder head phantom. Within Geant4, results obtained with three hadronic physics lists, FTFP_BERT, FTFP_INCLXX, and FTF_BIC, were compared with each other and with FLUKA predictions; differences were quantified as percentage deviations. In addition, the results for ⁴He and ¹²C ions were analytically compared with those for protons, the most abundant component of cosmic rays, at the same energies. These analyses are essential for assessing the sensitivity of dose estimates to the underlying physical models, improving confidence in computed dose values, and ultimately supporting the investigation of the radiobiological effects of cosmic radiation. The average of the absolute value of the relative difference observed in this study between the total dose values obtained for ⁴He ions using FLUKA and the physics models implemented in Geant4 ranged from 0.85% to 3.55%, while for ¹²C ions, it ranged from 0.002% to 3.14%. This parameter was also calculated for the primary and secondary dose components, and the observed differences were discussed. It is recommended that similar studies should be conducted for all particle species present in cosmic rays to properly assess the reliability and consistency of Monte Carlo codes in this area of research.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149114197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of high-resolution detector response for stereotactic patient-specific QA across different TPS-linac systems.","authors":"Sevim Sahin, Cemile Ceylan, Evren Ozan Göksel, Zeynep Özen","doi":"10.1007/s00411-026-01256-1","DOIUrl":"https://doi.org/10.1007/s00411-026-01256-1","url":null,"abstract":"<p><p>This study aimed to characterize the response and inter-system consistency of a high-resolution myQA SRS detector used for patient-specific quality assurance (PSQA) across different configurations of treatment planning system and linear accelerator (TPS-linac). A total of 20 clinically approved stereotactic radiosurgery / stereotactic body radiotherapy (SRS/SBRT) cases were included in a paired-study design to eliminate patient-specific anatomical bias. Each case was re-optimized on both Monaco-Versa HD (Agility 160 MLC) and Eclipse-TrueBeam STx (HD120 MLC) platforms, resulting in 40 unique plans. Doses from all plans were measured using the myQA SRS detector, with TrueBeam-based plans additionally verified via an electronic portal imaging device (EPID) for comparative detector analysis. Gamma passing rates (GPRs) (2%/1 mm to 3%/2 mm) and plan complexity metrics, including monitor units (MUs), segment number, and Modulation Factor (MF), were evaluated using non-parametric statistics. For the myQA SRS, mean GPRs ranged from 85.1% to 95.5% for Monaco and 80.6% to 92.9% for Eclipse, with no statistically significant differences observed between platforms (p > 0.05). Spearman's analysis confirmed that plan complexity did not correlate with QA outcomes (p > 0.05), indicating that the detector's response remains independent of modulation levels within clinical ranges. Comparative analysis between myQA SRS and EPID revealed systematic detector-dependent differences that became more pronounced at wider gamma criteria. Isolated low-passing outlier cases, associated with very small targets in steep dose-gradient regions, were observed for both detectors and were analyzed separately. Overall, the myQA SRS detector demonstrated high inter-system consistency, and appears to be a robust tool for PSQA of highly modulated stereotactic plans. The findings suggest that PSQA outcomes are more influenced by system-specific modelling and detector characteristics than by plan complexity alone.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149114137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Factors influencing dose delivery in rectal cancer radiotherapy using CBCT-guided intensity modulated techniques.","authors":"Geanina-Mirela Catona, Loredana G Marcu","doi":"10.1007/s00411-026-01255-2","DOIUrl":"https://doi.org/10.1007/s00411-026-01255-2","url":null,"abstract":"<p><p>This study investigates factors that affect dose delivery in rectal cancer radiotherapy and evaluates the resulting differences between planned and delivered treatment doses using intensity-modulated techniques. Twenty patients were included with 140 cone beam computed tomography (CBCT) images. A correlation analysis was conducted to ascertain the impact of detected misalignment on the Penta-Guide phantom on the planning target volumes (PTVs) and volumes of organs at risk (OARs), and whether shifts from CBCT were affected by patient mass changes. To facilitate a comparative analysis and evaluate dose delivery, Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) plans were simulated in the Monaco treatment planning system and further adapted to each CBCT using the Adapt-to-Shape (ATS) function. Moderate to strong correlations between Penta-Guide detected misalignments and the PTVs, bladder and bowel bag were observed, as well as a strong correlation between translational and rotational shifts and patient mass modifications during treatment. Thus, a reduction in target volume coverage was observed in comparison to the initial plans on CT, with VMAT providing a PTV coverage of nearly 95%, while IMRT resulted in an under-irradiated tumour volume with 93.4% coverage for calculated plans on CBCT. Regarding OARs, a slight decrease was observed in parameter values analyzed on CBCT for bladder (up to 5% for V40 with VMAT), while for bowel bag the evaluated parameters were up to 11% higher for IMRT and 10% for VMAT on CBCT. These results suggest that monitoring organ filling, patient mass, and quality assurance (QA)-related misalignments is essential in rectal cancer radiotherapy to minimize dose discrepancies.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149114148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of magnetic field orientation and strength on dose distributions in 6 MV photon beams: A Monte Carlo study.","authors":"Mohammed Rezzoug, Yassine Oulhouq, Omar Hamzaoui, Mustapha Zerfaoui, Abdeslem Rrhioua, Dikra Bakari","doi":"10.1007/s00411-026-01253-4","DOIUrl":"https://doi.org/10.1007/s00411-026-01253-4","url":null,"abstract":"<p><p>This study investigates the influence of magnetic field orientation (Ox, Oy, Oz) and strength (0-3 T) on percentage depth dose (PDD) and dose profile parameters for 6 MV clinical photon beams using Monte Carlo simulations. Monte Carlo simulations were performed using GATE (version 9.2) with a validated 6 MV phase space source. Three field sizes (10 × 10, 15 × 15, and 20 × 20 cm²) were evaluated under magnetic fields ranging from 0 to 3 T in increments of 0.5 along three orthogonal directions (Ox, Oy, Oz). PDD parameters including R₁₀₀, D₁₀₀, D₂₀₀, surface dose (Ds), and quality index (Qi) were analyzed. Dose profile characteristics including field size and penumbra width were evaluated in both X and Y directions. Magnetic field orientation and strength significantly affected dose distributions. For Ox and Oy orientations, R₁₀₀ decreased progressively with increasing field strength: from 16 to 17 mm at 0 T to 7-9 mm at 3 T across all field sizes. Surface dose increased substantially from 40 to 45% at 0 T to 58-65% at 3 T. For Oz orientation, R₁₀₀ showed minimal variation (10-13 mm across all field strengths), while surface dose increased more substantially to 56-66%. Penumbra width and field size demonstrated orientation-dependent variations, with minimal changes for Ox and Oy, but systematic reductions for Oz orientation. It is concluded that magnetic field presence substantially alters dose deposition patterns in an orientation-dependent manner. These findings are critical for MRI-guided radiotherapy systems and require specific dosimetric considerations for treatment planning and quality assurance protocols.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149075859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WITHDRAWN: Photon and electron specific absorbed fractions to pregnant female organs from maternal and fetal sources.","authors":"","doi":"10.1007/s00411-026-01250-7","DOIUrl":"10.1007/s00411-026-01250-7","url":null,"abstract":"<p><p>Ahead of Print article withdrawn by publisher.</p>","PeriodicalId":21002,"journal":{"name":"Radiation and Environmental Biophysics","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149075884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}