Zeitschrift fur medizinische Physik最新文献

{"title":"Adaptation of quality control pipeline for Skeletal Muscle 31P MR Spectroscopy at 3T and 7T.","authors":"D Pajuelo, R Klepochová, P Šedivý, M Dezortová, I Just, P Kordač, M Hájek, B Ukropcová, J Ukropec, P Szomolányi, P Taimr, L Horváth, M Dubský, D Sojáková, M Krššák","doi":"10.1016/j.zemedi.2026.05.004","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.05.004","url":null,"abstract":"<p><p>Analysis of dynamic phosphorus magnetic resonance spectroscopy (³¹P MRS) data is often hindered by variability in data quality. A quality control (QC) pipeline developed by Naëgel (2023) introduced six key parameters to ensure reliable ³¹P MRS results in large clinical datasets. This study tested the transferability of this QC scoring (QCS_REF) to two different research sites equipped with 3T and 7T MR systems and different ergometers. Twelve groups with the focus on frail and elderly subjects and patients with neurodegenerative diseases were included. The application of QCS_REF limits led to the improvement of the statistical power in some patient groups, but to the exclusion of substantial data for all our groups and experimental settings at both 3T and 7T. Only 28% of all recovery and exercise period data at 3T and 21% at 7T passed QCS_REF inclusion criteria. Therefore, two new sets of quality control criteria, QCS1 and QCS2, were proposed, reflecting achieved SNR of individual MR signalsand the patient phenotype included. We showed that the transferability of the QCS_REF did not depend on the magnetic field, the coil, or localization scheme. The new QCS did not significantly influence the mean recovery and exercise time constants of each group compared to QCS_REF. We verified that six proposed key parameters were adequate for an objective assessment of the quality of dynamic ³¹P MRS measurement at 3T as well as 7T. However, the patient group characteristics and experimental set-up significantly affect the ability to meet dynamic ³¹P MRS quality control thresholds, supporting the use of flexible QC criteria for robust data acquisition across diverse clinical populations.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148280878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complexity metrics for Tomotherapy: application to the verification of transferred plans.","authors":"L Simon, J Seguret, L Vieillevigne","doi":"10.1016/j.zemedi.2026.05.002","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.05.002","url":null,"abstract":"<p><strong>Purpose: </strong>To study the impact of transferring a treatment plan between two machines on the delivered dose, new complexity metrics based on Leaf Opening and Closing Times (LOT and LCT) were developed.</p><p><strong>Materials and methods: </strong>Basic tomotherapy treatment plans were created to identify the ranges of LOT that are accurately delivered and those that deviate from the planned values. Newly developed complexity metrics were derived from these ranges. These metrics from 103 clinical plans and 6 phantom plans were analyzed to identify treatment sites affected by short LCTs during plan transfer. A software tool was developed to estimate the additional dose associated with short LCTs, and these estimations were verified by measurements.</p><p><strong>Results: </strong>Opening time deviations were observed for short LOTs (below 50 ms) and short (but non-zero) LCTs (up to 40 ms). When a plan is created, no LOTs are generated in these regions. However, when a plan is transferred between two machines (e.g., in case of a breakdown), a fraction of LOTs equal to LOTmax (i.e., with no leaf closing) are converted into short LCTs. The additional dose due to these short LCTs could reach up to 3%. Affected treatment sites included pelvis, anal canal, and bone metastases. Measured dose discrepancies were consistent with estimations, with mean errors of 0.3% for phantom plans and 0.6% for clinical plans. Using an alternative transfer method, mean dose discrepancies decreased from 3% to less than 1% for all plans.</p><p><strong>Conclusions: </strong>To date, transferring Tomotherapy plans increases LOT distribution complexity by creating short LCTs. The additional dose due to short LCTs is significant for plans with high gantry rotation speed and \"hockey stick\" shaped LOTs distributions. An alternative transfer method can reduce delivery errors by eliminating short LCTs.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148045326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of CT dose-averaged detectability: a repeatability study.","authors":"Maximilian Göppel, Patrizia Kunert, Hugo de Las Heras Gala, Sebastian Trinkl, Augusto Giussani","doi":"10.1016/j.zemedi.2026.05.003","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.05.003","url":null,"abstract":"<p><p>In diagnostic radiology, it is essential to ensure that image quality is sufficiently good to support accurate diagnosis and patient safety. This is in accordance with the ALARA principle of keeping radiation exposure as low as reasonably achievable - taking into account economic and societal factors. Further, the detection of subtle low-contrast differences is critical for early disease detection, particularly in cases such as liver metastases. Iterative reconstruction algorithms have improved medical imaging by reducing noise, but their non-linear nature challenges traditional assessment metrics. Model observers like the Channelized Hotelling Observer provide task-specific evaluations suitable for non-linear systems. This study employs a previously proposed method for determining the dose-averaged detectability in computed tomography (CT) systems, focusing on minimizing systematic errors from measurement processes and phantom specimen variations. We conducted two repeatability analyses: intra-specimen, using the same CT scanner and phantom, and inter-specimen, using different specimens of the same phantom type. The study utilized a GE Brightspeed 16 scanner. The analyses revealed significant variations among different specimens, necessitating corrections for consistent comparison. The main correction underscores the importance of experimental verification of actual contrast values for accurate determination of the figure of merit (FOM) with multiple phantom specimens.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148008562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A probabilistic framework for risk-bounded patient-specific quality assurance in volumetric modulated arc therapy based on measured and calculated gamma pass rates.","authors":"Markus Schiebl, Petra Trnková, Gerd Heilemann, Michaela Jindráková, Sonja Tögl, Dietmar Georg, Wolfgang Lechner","doi":"10.1016/j.zemedi.2026.04.003","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.04.003","url":null,"abstract":"<p><p>This study introduces a probabilistic framework for patient-specific quality assurance (PSQA) in volumetric modulated arc therapy (VMAT), using gamma pass rates obtained from both measurement-based and independent calculation-based PSQA. The model quantifies the probability that treatment plans classified as acceptable by an independent dose calculation (IDC) algorithm would nevertheless fail measurement-based verification. This probability, referred to as the false omission rate, represents the residual risk of skipping measurements for plans classified as unproblematic by the calculation. Receiver operating characteristic (ROC) analysis demonstrated limited discriminative performance of the IDC, underscoring that reliance on calculation alone entails non-negligible miss probabilities. In a retrospective cohort of 1346 clinical VMAT plans across multiple anatomical sites, false omission rates ranged from below 1% in well-represented groups such as prostate to above 20% for sparsely represented treatment regions. Based on these empirically derived miss probabilities, the framework allows the definition of measurement intervals that constrain the cumulative probability of undetected plan failure below a predefined institutional threshold. In this way, PSQA strategies involving reduced measurement schedules for selected plans can be quantitatively assessed and constrained within explicit probabilistic safety limits. The proposed method is transparent, independent of complex machine learning models, and directly applicable to empirical QA datasets. By making the risk of undetected failure explicit and quantifiable, it enables structured, risk-informed PSQA policies grounded in defined safety constraints.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147944467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Apparent tissue sodium concentration quantification across reconstruction methods with different partial volume effect reduction - A preliminary study.","authors":"Olgica Zaric, Carmen Leser, Vladimir Juras, Alex Farr, Pavol Szomolanyi, Malina Gologan, Stanislas Rapacchi, Laura Villazan Garcia, Haider Ali, Christian Singer, Siegfried Trattnig, Christian Licht, Ramona Woitek","doi":"10.1016/j.zemedi.2026.05.001","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.05.001","url":null,"abstract":"<p><strong>Introduction: </strong>In sodium (²³Na) magnetic resonance imaging (MRI), partial volume effects (PVE) are one of the most common causes of errors in the in vivo quantification of apparent tissue sodium concentration (aTSC). Advanced image reconstruction algorithms, such as compressed sensing (CS), have the potential to reduce PVE. This study aimed to investigate the feasibility of CS-based reconstruction techniques for improving image quality, and to assess whether differences in aTSC exist when images are reconstructed using different methods.</p><p><strong>Subjects and methods: </strong>In this study, three healthy participants and 12 female participants with breast cancer were examined on a 7T MRI scanner. ²³Na-MRI images were reconstructed using weighted total variation (wTV), directional total variation (dTV), anatomically guided total variation (AG-TV) and adaptive combine (ADC) methods. The consistency of tumor volume delineations based on sodium data was assessed using the Dice score, and aTSC quantification was performed for various image reconstruction methods. Pairwise comparisons of aTSC values between reconstruction methods (wTV, dTV, AG-TV, and ADC) were conducted using the Wilcoxon signed-rank test.</p><p><strong>Results: </strong>All methods provided breast MRI images with well-preserved sodium signal and tissue structures. The mean Dice scores for wTV, dTV, and AG-TV were 65±11%, 72±9%, and 75±6%, respectively. Mean aTSC (in mmol/L) values in glandular tissue were 52.0±4.0 for wTV, 55.0±4.0 for dTV, 63±3.0 for AG-TV, and 69.0±3.0 for ADC reconstructions. In adipose tissue, mean values of aTSC were 32.0±4.0, 29.0±3.0, 19.0±2.0, and 23.0±3.0 for wTV, dTV, AG-TV, and ADC, respectively. In tumors, mean aTSC were as follows: 80.0±5.0 for wTV, 85.0±5.0 for dTV, 99.0±5.0 for AG-TV, and 105.0±7.0 for ADC. Post-hoc Wilcoxon signed-rank tests showed that AG-TV differed significantly from both wTV and dTV across all tissues (all p< 0.001), and that wTV also differed significantly from dTV (p=0.038 in gland, p=0.027 in adipose, and p=0.009 in tumor).</p><p><strong>Conclusion: </strong>Tumor appearance and aTSC estimations depend on the reconstruction method and parameter selection, likely due to differences in PVE reduction. Among the evaluated approaches, AG-TV showed the most favorable overall performance for ²³Na-MRI of breast tumors under the studied conditions.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147848367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Error detection sensitivity and operational efficiency of phantom-based and phantom-less patient-specific quality assurance in proton therapy.","authors":"Lukas Cornelius Wolter, Yazeed Ghannam, Kenneth Poels, Stefan Menkel, Fabian Hennings, Kevin Souris, Theresa Lenk, Kristin Stützer, Christian Richter","doi":"10.1016/j.zemedi.2026.04.002","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.04.002","url":null,"abstract":"<p><strong>Background and purpose: </strong>In proton therapy (PT), patient-specific quality assurance (PSQA) is an important component of the measures which ensure accurate and safe treatment delivery. Traditional phantom-based PSQA is resource-intensive and may miss clinically relevant data transfer and delivery errors. This study compared the sensitivity and operational effort of established phantom-based methods versus an automated, phantom-less alternative based on the increasingly utilized log file-based approach.</p><p><strong>Materials and methods: </strong>We evaluated phantom-based (specifically including dose measurements & manual physics checks) and phantom-less (specifically based on log file-based QA & automated physics checks) PSQA workflows. Twenty-nine artificial error scenarios were introduced to a clinically delivered head-and-neck plan. Error detection sensitivity was determined via the percentage of scenarios detected by each workflow. Operational effort was quantified by counting mouse clicks and manual parameter entries in clinical systems.</p><p><strong>Results: </strong>Phantom-less PSQA detected 90% of simulated errors, outperforming phantom-based PSQA detecting only 52% at clinically realistic measurement conditions. Specifically, log file-based QA alone detected 83% of scenarios versus 10% detected by phantom-based measurements. Manual and automated plan parameter checks showed an equal sensitivity, detecting 48% of scenarios. The more automated, phantom-less alternative could reduce operational effort by at least one third of the currently required mouse clicks.</p><p><strong>Conclusions: </strong>Phantom-less PSQA based on log file-based QA and automated physics checks provided higher error detection sensitivity and significantly reduced manual operational effort compared to conventional phantom-based and manual methods. These findings support its integration into clinical practice, a key objective of many PT centers.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147794015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive geometry-based plan quality score for lung VMAT.","authors":"Johann Brand, Juliane Szkitsak, Rafael Lobao, Bernd-Niklas Axer, Lucas Pieper, Oliver J Ott, Marlen Haderlein, Florian Putz, Rainer Fietkau, Stefanie Corradini, Christoph Bert, Stefan Speer","doi":"10.1016/j.zemedi.2026.03.014","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.03.014","url":null,"abstract":"<p><p>Volumetric-modulated arc therapy (VMAT) treatment planning for lung tumors requires balancing adequate planning target volume (PTV) coverage with optimal organ-at-risk (OAR) sparing. However, plan quality varies due to differences in planner expertise, preferences, and especially patient anatomy. This study introduces a Comprehensive Plan Score (CPS) for lung VMAT plans, integrating geometry-based OAR quality indices derived from overlap volume histograms (OVH) and overlap-z-histograms (OZH). CPS was developed by combining normalized target and OAR scores, including geometry-based metrics derived from OVH and OZH. Relative weights were learned from blinded pairwise plan comparisons performed by four senior radiation oncologists (ROs). A total of 35 manual versus automated lung VMAT plan pairs were evaluated, with 20 cases used for training and 15 for independent testing. Across all comparisons, ROs expressed a clear preference in 81% of cases, while 19% were judged equivalent. Inter-observer agreement was fair (Fleiss' κ = 0.36), with pairwise Cohen's κ ranging from 0.13 to 0.71. In the independent test cohort, CPS using the preference-trained weighting set matched the ROs consensus in 11/15 cases. Applying an equivalence threshold (ΔCPS = 0.01) increased agreement to 13/15 cases (86%). In conclusion, the CPS provides a more objective and geometry-based measure of lung VMAT plan quality. By quantifying achievable OAR sparing based on prior data, it supports consistent and standardized plan evaluation, potentially improving the reproducibility and overall quality of radiotherapy planning.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147617340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Averaged anatomy CT in weekly treatment quality control and offline adaptive intensity modulated proton therapy of head and neck cancers.","authors":"Mark Ka Heng Chan","doi":"10.1016/j.zemedi.2026.03.013","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.03.013","url":null,"abstract":"<p><p>Adaptive intensity modulated proton therapy (IMPT) for head and neck cancer commonly relies on weekly repeated CT scans (rCTs) to assess anatomical changes and determine whether plan adaptation is required. However, a single rCT often fails to represent the daily anatomical variability observed on daily CBCTs, particularly in soft tissue regions subject to physiologic motion such as the tongue base, and supraglottic airway. This work evaluates an averaged‒anatomy CT (Ave_rCT) generated from deformably registered rCT and multiple preceding daily synthetic CTs (sCTs), following an approach previously validated in photon therapy. Twelve oropharyngeal cancer patients with mid‒treatment adaptation were retrospectively reviewed. Adaptive plans generated using Ave_rCT (AveAP) were compared with clinical adaptive plans (ClinAP) based on a single rCT. Dosimetric evaluation on subsequent rCTs showed comparable robust voxmin CTV D98, voxmax body Dmax and serial OAR D0.03cc, and predicted ΔNTCP between the two methods. The Ave_rCT tended to resemble subsequent weekly anatomy more closely than an individual rCT resulting in relatively smaller inter‒patient variability in target dose coverage and hot spot across post‒adaptation time points. Ave_rCT may improve the robustness of adaptation decision‒making by providing a more representative and stable anatomical reference compared to current practice of relying on single rCT. It appears to be a practical and efficient alternative to single or multi‒CT robust optimization in the offline-adaptive IMPT of head and neck cancers.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147577194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Image-based modeling of individual far-field resistance in cochlear implant recipients.","authors":"Benjamin Bircher, Stephan Schraivogel, Philipp Aebischer, Marco D Caversaccio, Wilhelm Wimmer, Stefan Weder","doi":"10.1016/j.zemedi.2026.03.012","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.03.012","url":null,"abstract":"<p><p>Cochlear implants (CIs) are effective auditory neuroprostheses, but performance varies across patients. One factor contributing to this variability is the spread of electrical current within the cochlea, which reduces spectral resolution and limits speech understanding. Far-field resistance, which can be measured directly, reflects current flow through perilymph and surrounding tissue and may be influenced by patient-specific anatomy. We developed an image-based model to automatically predict far-field resistance profiles using patient-specific cochlear geometries derived from preoperative computed tomography (CT) scans. In a retrospective analysis of 36 CI cases, surface meshes of the scala tympani and scala vestibuli were automatically segmented. Electrode positions were extracted from postoperative CT scans for validation purposes. Far-field resistance was estimated by computing cumulative resistances along longitudinal pathways within the scalae. The model systematically overestimated resistances by up to a factor of 5.2 depending on electrode insertion depth. After systematic deviation correction, high agreement with measured values was achieved in 33 of 36 subjects (root mean square error less than 0.15 kΩ, Spearman ρ=0.83), while outliers suggested atypical current spread due to electrode positioning, tissue contact, or alternative conductive pathways. The image-based model captured subject-specific resistance trends and apical electrode variability better than a group-average reference, though basal predictions were affected by near-field contributions and segmentation uncertainties. These results demonstrate that individualized CT-based modeling can approximate far-field resistance profiles and could enable further research on the interpretation of intracochlear current flow. Our approach could use routinely acquired preoperative imaging to complement the measured resistance, enabling the interpretation of inter-subject variability and the identification of atypical profiles potentially related to electrode positioning or tissue changes. The approach could be integrated into clinical workflows and extended with advanced modeling techniques to support surgical planning, postoperative monitoring, and device programming, linking anatomical imaging with functional impedance assessment.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147494970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Value of the Acuros reconstruction CBCT algorithm for conventional (non-HyperSight) Ethos systems.","authors":"Erik B van Dieren, Anieck E Ter Braak, Esther Bosman, Sven Schwieters, Jeroen Veltman, Judith J Dasselaar","doi":"10.1016/j.zemedi.2026.03.002","DOIUrl":"https://doi.org/10.1016/j.zemedi.2026.03.002","url":null,"abstract":"<p><strong>Background and purpose: </strong>Since the introduction of CBCT in the field of radiotherapy, there has been an increasing interest to adapt to anatomy changes during treatment. Since 2019, CBCT based online adaptive radiotherapy is feasible with Varian's Ethos, but CBCTs have low contrast, in particular in the pelvis. This study examines the added value of the Acuros algorithm reconstruction, for phantom and clinical pelvis CBCTs, for non-HyperSight Ethos systems (NHES).</p><p><strong>Methods and materials: </strong>Data from two NHES systems were used. Firstly, bi-weekly CBCT scans were made using an anthropomorphic pelvis phantom, and CT contours were propagated. Using these, CBCTs, SNR, CNR, uniformity, and resolution were calculated. Secondly, CBCTs were analyzed for five prostate patients treated adaptively, using three sessions. The 2nd CBCT, just before beam on in the adaptive sessions, was reconstructed using Acuros. Besides analysis similar to the phantom study, seven observers were asked to score on various items.</p><p><strong>Results: </strong>For the phantom study, the Acuros reconstruction is consistently superior to iCBCT in terms of contrast to noise, signal to noise and uniformity, but spatial resolution is similar. For clinical CBCTs, Acuros results in better contrast to noise, uniformity, and resolution. In accordance, observers usually score Acuros images as better or similar (85-95%) for the adaptive task than iCBCT.</p><p><strong>Conclusions: </strong>In a pelvis phantom, Acuros outperforms standard reconstruction for most parameters, or it is equal. For clinical data, Acuros is usually better, and is generally preferred by observers. Hence, use of Acuros for NHES is recommended.</p>","PeriodicalId":101315,"journal":{"name":"Zeitschrift fur medizinische Physik","volume":" ","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147481486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}