Physica Medica-European Journal of Medical Physics最新文献

{"title":"Evaluation of an updated pencil beam algorithm for enhanced dosimetric accuracy in stereotactic radiotherapy","authors":"Paul Retif ,&nbsp;Motchy Saleh ,&nbsp;Abdourahamane Djibo Sidikou ,&nbsp;Romain Letellier ,&nbsp;Anwar Al Salah ,&nbsp;Estelle Pfletschinger ,&nbsp;Fabian Taesch ,&nbsp;Emilie Verrecchia-Ramos ,&nbsp;Xavier Michel","doi":"10.1016/j.ejmp.2025.104941","DOIUrl":"10.1016/j.ejmp.2025.104941","url":null,"abstract":"<div><h3>Introduction</h3><div>This study evaluates enhancements introduced in version 4.0 of Brainlab’s Pencil Beam algorithm within the Elements treatment planning system (TPS) for radiotherapy dose calculations. These updates include a new scatter model to improve dose calculation accuracy and updated commissioning recommendations involving asynchronous sweeping gap (a-SG) measurements to refine multileaf collimator (MLC) parameters such as dynamic leaf shift (DLS) and tongue-and-groove (TG) size.</div></div><div><h3>Materials and methods</h3><div>The original (version 3.0) and updated (version 4.0) implementations of the Pencil Beam algorithm were compared using a Varian TrueBeam STx accelerator with 6-MV flattening filter-free energy and high-definition MLC. Dosimetric accuracy was assessed through phantom-based point dose and volumetric measurements for clinical cases, including treatments for single and multiple brain metastases with volumetric modulated arc therapy (VMAT) and dynamic conformal arcs (DCA).</div></div><div><h3>Results</h3><div>The updated algorithm demonstrated superior performance compared to the original version. Point dose measurements showed a reduction in discrepancies between calculated and measured doses, with improvements of up to 2.1 % for smaller targets. Volumetric measurements revealed increased gamma pass rates, with improvements of up to 15.9 % at a 95 % dose threshold in VMAT and DCA treatments.</div></div><div><h3>Conclusion</h3><div>These findings highlight advancements in dose calculation accuracy, particularly for small fields and multiple targets. These improvements of the Pencil Beam algorithm, driven by the scatter model and enhanced MLC parameter commissioning, contribute to more reliable dose predictions. As findings are specific to the 6-MV FFF beam and TrueBeam STx system, further investigations are needed for other energies and linear accelerators.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104941"},"PeriodicalIF":3.3,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study for revising diagnostic reference levels for intra-oral radiology in Cyprus","authors":"Anastasia C. Hadjiconstanti ,&nbsp;Constantinos Koshiaris ,&nbsp;Constantinos Zervides","doi":"10.1016/j.ejmp.2025.104930","DOIUrl":"10.1016/j.ejmp.2025.104930","url":null,"abstract":"<div><h3>Background</h3><div>Intra-oral radiography (IOR) is an imaging technique that uses X-rays to diagnose dental conditions. Establishing Diagnostic Reference Levels (DRLs) is crucial to optimising radiation doses and enhancing patient safety.</div></div><div><h3>Objective</h3><div>This study was undertaken to propose national DRLs for IOR in Cyprus for both children and adults. The study also sought to compare dose values across different detector types, a task of significant importance in dental radiography.</div></div><div><h3>Methods</h3><div>Data was collected from 115 intraoral units in 87 private centres in Cyprus, using incident air kerma (Ki) as the parameter. Statistical analysis was conducted based on Adulthood and detector types, such as direct digital detector (DDD), indirect digital detector (IDD) and film.</div></div><div><h3>Results</h3><div>The study revealed variability in dosing values, with third-quartile doses higher for adults than paediatric patients. DDD exhibited the lowest dose values, while film had the highest. Proposed DRLs were notably lower than the current valid DRL in Cyprus, emphasising the need for re-establishment.</div></div><div><h3>Conclusion</h3><div>The values obtained can aid the national authority in establishing national DRLs in IOR. Establishing national intraoral DRLs in Cyprus is a crucial step towards ensuring the safety and fairness of dental care in the country. With the implementation of this initiative, patients can be assured that they are receiving the highest quality of care possible.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104930"},"PeriodicalIF":3.3,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[18F]FDG administered activity reduction capabilities of a 32-cm axial field-of-view solid-state digital bismuth germanium oxide PET/CT system while maintaining EARL compliance","authors":"Alina van de Burgt ,&nbsp;Petra Dibbets-Schneider ,&nbsp;Fotis Kotasidis ,&nbsp;Lioe-Fee de Geus-Oei ,&nbsp;Daphne D.D. Rietbergen ,&nbsp;Floris H.P. van Velden","doi":"10.1016/j.ejmp.2025.104935","DOIUrl":"10.1016/j.ejmp.2025.104935","url":null,"abstract":"<div><h3>Purpose</h3><div>To assess the lower [¹⁸F]FDG limit in administered activity and/or scan time reduction capabilities of a digital-BGO 32-cm axial field-of-view PET system while being compliant with current and updated EANM Research Ltd Fluorine-18 accreditation specifications (EARL₁ and EARL₂).</div></div><div><h3>Methods</h3><div>EARL₁ and EARL₂ compliance of the digital-BGO system (Omni Legend 32 cm) was tested for several reconstructions, including those that apply precision deep learning-based image enhancement (PDL) as postprocessing, using the calibration QC and NEMA IEC phantom measurements. The image quality QC scan was repeated every hour for 7 h, with each subsequent hour representing a lower administered activity, and reconstructed for various times per bed position, i.e. 30, 60, 120, 180, and 300 s. For each of the image quality QC images, coefficient of variation (COV) of the background compartment, and mean, maximum and peak activity concentration recovery coefficients (RC_mean, RC_max and RC_peak) of differently-sized spheres were calculated and compared to current and updated EARL accreditation specifications.</div></div><div><h3>Results</h3><div>When we apply 1 min per bed position for PET acquisition, [¹⁸F]FDG administration can be reduced by a factor of ∼ 4 for EARL₁, by a factor of ∼ 8 for EARL₂ (2 mm voxels) and by a factor of ∼ 4 for EARL₂ (4 mm voxels) using both standard reconstructions and PDL post-processing compared to current EANM recommendations for [¹⁸F]FDG administration (7 MBq^<img>min^<img>bed^-1<img>kg^-1).</div></div><div><h3>Conclusions</h3><div>Reduction in [¹⁸F]FDG administered activity is possible by at least a factor 4 for 1 min/bed with the Omni Legend 32 cm PET/CT while maintaining EARL₁ and EARL₂ compliance.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104935"},"PeriodicalIF":3.3,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Working thresholds for in-vivo dosimetry in EPIGray based on a clinical, anatomically-stratified study","authors":"Sandra Williamson Puente,&nbsp;Miguel Cámara Gallego,&nbsp;David Sevillano Martínez,&nbsp;Rafael Colmenares Fernández,&nbsp;Juan David García Fuentes,&nbsp;Ana Belén Capuz Suárez,&nbsp;Rafael Morís Pablos,&nbsp;María José Béjar Navarro,&nbsp;Daniel Prieto Morán,&nbsp;Pablo Galiano Fernández,&nbsp;Rubén Chillida Rey,&nbsp;Carlos Rodríguez-Manzaneque Sosa,&nbsp;Feliciano García-Vicente","doi":"10.1016/j.ejmp.2025.104933","DOIUrl":"10.1016/j.ejmp.2025.104933","url":null,"abstract":"<div><h3>Purpose</h3><div>To obtain tolerance levels for working with the EPID-based EPIgray in vivo dosimetry system.</div></div><div><h3>Methods</h3><div>Dose differences between planned and delivered treatments in various anatomical areas, including the gastro-intestinal, urological, rectum and anal canal, gynecological, breast, head and neck, and lung regions, were analyzed across 5,791 fractions. Whether or not the dose differences at each location are symmetrical with respect to zero and adhere to a normal distribution is then checked. Linear regression analysis was applied to check for temporal drift in lung and head and neck treatments. A water equivalent phantom and another with a water-polystyrene interface is used to estimate the dose difference intrinsic to the measurement system. Furthermore, appropriate dose distribution in two treatments is verified using radiochoromic film.</div></div><div><h3>Results</h3><div>Normal distribution was not observed in any region, and only two showed symmetry around zero. The mean dose differences were: (0.33 ± 6.32) % for the gastro-intestinal system, (−1.31 ± 3.16) % for the gynaecological area, (0.79 ± 4.55) % for VMAT-breast, (3.48 ± 4.00) % for 3DCRT-breast, (0.70 ± 3.20) % for head and neck, (5.63 ± 5.48)% for lung, (−1.36 ± 2.98) % for rectum and anal canal, and (0.13 ± 3.53) % for the urological system.</div></div><div><h3>Conclusion</h3><div>EPIgray should support tolerance levels asymmetric with respect to zero, given the positive deviation observed in mean dose for lung, breast, and head and neck regions. Additionally, the system’s ability to detect dose variations during treatment could help identify changes in tumor volume.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104933"},"PeriodicalIF":3.3,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment and improvement of the quality of radiotherapy treatment planning CT images using a clinically validated phantom based method and a multicentre intercomparison","authors":"Anne T. Davis ,&nbsp;Andrew Bird ,&nbsp;Lorraine Cowley ,&nbsp;Oliver Donnelly ,&nbsp;Mostafa ELHaddad ,&nbsp;Cheryl Evans ,&nbsp;Tracey Kearton ,&nbsp;Rachel Morrison ,&nbsp;David Nash ,&nbsp;Joshua Naylor ,&nbsp;Joel Palmer ,&nbsp;Katherine Potterton ,&nbsp;Anand M. Ravindran ,&nbsp;Daniel Sandys ,&nbsp;Athina Sdrolia ,&nbsp;Antonio de Stefano ,&nbsp;Maja Uherek ,&nbsp;Zoe Walker ,&nbsp;Antony L. Palmer ,&nbsp;Andrew Nisbet","doi":"10.1016/j.ejmp.2025.104912","DOIUrl":"10.1016/j.ejmp.2025.104912","url":null,"abstract":"<div><h3>Purpose</h3><div>To develop a phantom method of image quality assessment for radiotherapy planning CT protocols (head and neck (H&amp;N) and prostate) and validate results against clinical image quality. Test with data from different scanners and suggest protocol adjustments.</div></div><div><h3>Methods</h3><div>Macros measured patient water-equivalent diameter and noise from clinical CT images. Target transfer function (TTF), contrast, noise-power spectrum (NPS), detectability index and the edge visibility of a low contrast target were measured using Catphan 604 and bespoke phantoms. Ten centres scanned the phantoms with modified clinical protocols and collected data from patient images using the macros. Clinical experts, ranked the quality of images for contouring and correlated results against phantom metrics.</div></div><div><h3>Results</h3><div>Clinical image review showed a large range of results from different scanners for H&amp;N scans and fewer differences for prostate. The phantom metrics best correlated with high clinical image scores were, for H&amp;N: high TTF50 (r = 0.73, <em>p</em> = 0.003), contrast (r = 0.58, p = 0.003) and target edge visibility (r = 0.70, <em>p</em> = 0.004); for prostate: high TTF50 (r = 0.83, <em>p</em> = 0.002), low noise (r = 0.37, <em>p</em> = 0.26) and target edge visibility (r = 0.59, <em>p</em> = 0.05). Hence, optimal contrast, resolution and noise are important for good contouring image quality. Reconstruction kernel, field of view and noise, or X-ray tube current and rotation time, are possible parameters for adjustment.</div></div><div><h3>Conclusions</h3><div>This phantom method (using Catphan 604) was a good surrogate for clinical quality assessment of CT images for radiotherapy contouring. Results identified the poorest performing scanners, allowing recommendations for image quality improvement and confirming scan protocol optimisation is necessary in some centres.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104912"},"PeriodicalIF":3.3,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dosimetry audit service in Italy: Results of the partnership between Italian Association of Medical Physics (AIFM) and Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI)","authors":"Paola Martucci ,&nbsp;Alessia Embriaco ,&nbsp;Maria Pimpinella ,&nbsp;Vanessa De Coste ,&nbsp;Serenella Russo ,&nbsp;Pierino De Felice ,&nbsp;Michele Stasi ,&nbsp;Christian Fiandra","doi":"10.1016/j.ejmp.2025.104925","DOIUrl":"10.1016/j.ejmp.2025.104925","url":null,"abstract":"<div><h3>Purpose</h3><div>The Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI) and the Italian Association of Medical Physics (AIFM) offer a certified audit service to radiotherapy (RT) centers for reference dosimetry.</div></div><div><h3>Methods</h3><div>Audits are provided for photon beams in the range 6–18 MV including flattening filter free C-arm Linac, CyberKnife and TomoTherapy beams. A dosimeter consisting of a set of TLD chips embedded in a PMMA waterproof holder is used. TLDs are calibrated in terms of absorbed dose to water in the ENEA-INMRI reference <span><math><mrow><msup><mrow><mspace></mspace></mrow><mn>60</mn></msup><mi>C</mi><mi>o</mi></mrow></math></span> γ-beam. Correction factors accounting for energy dependence, signal reproducibility and response stability are applied to evaluate absorbed dose. For each beam audited, irradiation of two dosimeters with 2 Gy is required in reference conditions, according to the international dosimetry protocols. Audit performance is evaluated in terms of the<!--> <!-->E_n <!-->score: it is satisfactory if |E_n| ≤ 1.0.</div></div><div><h3>Results</h3><div>Audit was successfully performed for 94<!--> <!-->beams in 34 Italian<!--> <!-->RT<!--> <!-->centers. Nominal beam energies analysed were 6 MV (38.3 %), 6 MV FFF (33.0 %), 10 MV (12.8 %), 10 MV FFF (4.2 %), 15 MV (9.6 %) and 18 MV (2.1 %). The<!--> <!-->E_n <!-->scores are normally distributed with 95 % of data between −0.54 and 0.7; 99.5 % of values are in the range [−1.0,1.0] and 81.1 % are in the optimal range [−0.5,0.5]. As for the single unsatisfactory result, data from the form filled in by the RT center allowed ENEA-INMRI to identify an error in the measurement setup.</div></div><div><h3>Conclusions</h3><div>Results of remote audits have shown excellent performance of Italian RT centers.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104925"},"PeriodicalIF":3.3,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and clinical application of a probabilistic robustness evaluation tool for pencil beam scanning proton therapy treatments","authors":"Francesco Fracchiolla ,&nbsp;Lamberto Widesott ,&nbsp;Roberto Righetto ,&nbsp;Carlo Algranati ,&nbsp;Dante Amelio ,&nbsp;Annalisa Trianni ,&nbsp;Edmond Sterpin ,&nbsp;Stefano Lorentini","doi":"10.1016/j.ejmp.2025.104938","DOIUrl":"10.1016/j.ejmp.2025.104938","url":null,"abstract":"<div><h3>Purpose</h3><div>to implement a probabilistic-Robustness-Evaluation (pRE) tool for proton therapy treatments and to correlate these results with the worst-case approach (wRE) implemented in commercial TPS for clinical applications.</div></div><div><h3>Materials and Methods</h3><div>12 skull base patients were planned with a robust multiple field optimization (MFO) approach. 10 years of machine QA were analysed to derive the uncertainties of our treatment system (beam delivery and patient positioning system). For a large cohort of patients, post-treatment imaging was acquired to determine the intra-fraction uncertainty. The pRE, considered explicitly all these uncertainties, the fractionation and range uncertainty. For each plan a wRE with different combinations of range and setup uncertainties was simulated. wRE results were then compared, in terms of target coverage and OAR dose limits, with pRE results.</div></div><div><h3>Results</h3><div>43,400 dose distributions were analysed. pRE simulations lasted 18.6 h (±11.5 h). The results showed that the combination of wRE uncertainty parameters that surrogated the best pRE results with a confidence level of 95 % were (1.0 mm/3.5 %). The median OAR’s dose indexes difference (D₁/D_1cc) between pRE and wRE was 1.90 (±1.49) GyRBE, while for target D₉₈ and D₉₅ it was −0.66(±0.95) and −0.67 (±0.52) GyRBE, respectively.</div></div><div><h3>Conclusion</h3><div>A tool able to explicitly simulate the source of treatment uncertainties and the effect of the fractionation was implemented to have a more realistic evaluation of plan robustness. This tool was used to find the best wRE parameters that surrogate the pRE results while maintaining clinically acceptable timing. These results are now used in our clinical workflow.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104938"},"PeriodicalIF":3.3,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143396257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative analysis of machine learning models for predicting pathological complete response to neoadjuvant chemotherapy in breast cancer: An MRI radiomics approach","authors":"Alessia D’Anna ,&nbsp;Carlo Aranzulla ,&nbsp;Carlo Carnaghi ,&nbsp;Francesco Caruso ,&nbsp;Gaetano Castiglione ,&nbsp;Roberto Grasso ,&nbsp;Anna Maria Gueli ,&nbsp;Carmelo Marino ,&nbsp;Francesco Pane ,&nbsp;Alfredo Pulvirenti ,&nbsp;Giuseppe Stella","doi":"10.1016/j.ejmp.2025.104931","DOIUrl":"10.1016/j.ejmp.2025.104931","url":null,"abstract":"<div><h3>Purpose</h3><div>The aim of this work is to compare different machine learning models for predicting pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) in breast cancer using radiomics features from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).</div></div><div><h3>Method</h3><div>The study included 55 patients with breast cancer, among whom 18 achieved pCR and 37 did not respond completely to NAC (non-pCR). After some pre-processing steps, 1446 features were extracted and corrected for batch effects using ComBat. Five machine learning algorithms, namely random forest (RF), decision tree (DT), logistic regression (LR), k-nearest neighbors (k-NN), and extreme gradient boosting (XGB), were evaluated using area under the receiver operating characteristic curve (AUC), accuracy, precision, recall, and F1 score as classification metrics. A Leave-Group-Out cross validation (LGOCV) was applied in the outer loop.</div></div><div><h3>Results</h3><div>RF and DT models exhibited the highest performances compared to the other algorithms. DT achieved an accuracy of 0.96 ± 0.07, and RF achieved 0.95 ± 0.05. The AUC values for RF and DT were 0.98 ± 0.06 and 0.94 ± 0.07, respectively. LR and k-NN demonstrated lower performance across all metrics, while XGB showed competitive results but slightly lower than RF and DT.</div></div><div><h3>Conclusions</h3><div>This study demonstrates the potential of radiomics and machine learning for predicting pCR to NAC in breast cancer. RF and DT models proved to be the most effective in capturing underlying patterns in radiomics data. Further research is required to validate and strengthen the proposed approach and explore its applicability in diverse radiomics datasets and clinical scenarios.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104931"},"PeriodicalIF":3.3,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A high magnetic resonance imaging (MRI) contrast agar/silica-based phantom for evaluating focused ultrasound (FUS) protocols","authors":"Antria Filippou,&nbsp;Nikolas Evripidou,&nbsp;Christakis Damianou","doi":"10.1016/j.ejmp.2025.104932","DOIUrl":"10.1016/j.ejmp.2025.104932","url":null,"abstract":"<div><h3>Purpose</h3><div>Thermal ablation therapies require tissue mimicking phantoms for evaluating novel systems. Herein, an agar phantom exhibiting high magnetic resonance imaging (MRI) contrast to noise ratio (CNR) was developed for testing focused ultrasound (FUS) protocols.</div></div><div><h3>Methods</h3><div>Four agar based phantoms (6 % w/v) were fabricated with varied silica concentrations (0, 2, 4, or 6 % w/v) and subjected to FUS inside a 3 T MRI. T2-Weighted Fast Spin Echo (T2-W FSE) images were acquired after sonications to assess the effect of varied silica on CNR of inflicted lesions. The highest CNR phantom was sonicated and its proton resonance frequency (PRF) coefficient, thermal dose denaturation threshold and ability to sustain good lesion CNR 0–44 min post exposures were assessed.</div></div><div><h3>Results</h3><div>T2-W median lesion CNR between 1.5–453.5 was observed, exponentially increasing with increased silica concentration. High CNR was achieved with 4 % w/v silica, with the PRF coefficient of the phantom calculated at −0.00954 ppm/°C. The thermal dose denaturation threshold was revealed at 2 × 10⁶ CEM43°C by comparing thermal dose maps with T2-W FSE lesion hyperenhancement. Progressive lesion CNR loss was observed, with CNR lost 28 min after sonications.</div></div><div><h3>Conclusions</h3><div>The proposed phantom possesses excellent T2-W contrast of inflicted lesions while exhibiting a tissue like PRF coefficient and can thus constitute an inexpensive reusable tool for validating FUS systems and protocols.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104932"},"PeriodicalIF":3.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of the use of synthetic CT produced by deformable image registration of planning CT and CBCT in adaptive radiotherapy treatments of head and neck cancers","authors":"Sanju,&nbsp;Ashutosh Mukherji,&nbsp;Sambit S. Nanda,&nbsp;Shubham Dokania,&nbsp;Alka Kataria,&nbsp;Narender Kumar,&nbsp;Vinay Saini,&nbsp;Sanjay Barman,&nbsp;Dandpani R. Epili,&nbsp;Ajay Choubey,&nbsp;Ninad H. Patil,&nbsp;Ajay Krishnan","doi":"10.1016/j.ejmp.2025.104929","DOIUrl":"10.1016/j.ejmp.2025.104929","url":null,"abstract":"<div><h3>Introduction</h3><div>The present study uses deformable image registration to produce synthetic CT (sCT) images and investigate their use in treatment planning and improving clinical judgment in assessing the need for adaptive radiotherapy (ART).</div></div><div><h3>Methods</h3><div>A total of 30 patients with squamous cell carcinoma of the head and neck (HNSCC) who underwent ART were included in this study. The patients considered for adaptive planning, were re-simulated within 1–2 days. Both the Day 1 planning CT (pCT) and acquired CBCT were imported in Velocity® and a new sCT was created. The new treatment plan on re-simulation CT (rCT) which was planned for treatment delivery was recalculated on sCT. The geometric differences (Volume, Dice Similarity coefficient (DSC), mean distance to agreement (MDA)) in structures and dosimetric differences (Gamma analysis, mean doses and other DVH parameters) in treatment plans between the two images (sCT and rCT) were compared.</div></div><div><h3>Results</h3><div>The evaluation between sCT and rCT revealed that the average DSC and MDA for all the structures obtained was 0.86(0.05) and 1.15(0.20) respectively. Global gamma passing rate for 3 %, 3 mm was 96.85 ± 2.10 %. Mean dose for OARs and PTVs were found to be similar (difference within 3 %) in the two images.</div></div><div><h3>Conclusion</h3><div>sCT can be used to predict the per fraction dose delivered to the patient and could be a better alternative than only relying on clinical judgments, to take the patient for ART. Further work needs to be done on the use of sCT images to replace rCT images for ART.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104929"},"PeriodicalIF":3.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}