Journal of Applied Clinical Medical Physics最新文献

{"title":"Evaluation of the system accuracy of frameless stereotactic radiosurgery using a combination of cone beam CT, six degrees of freedom couch, and surface image-guided systems.","authors":"Hao-Wen Cheng, Jonathan Li, Sheng-Hsuan Sun, Guanghua Yan, Chihray Liu","doi":"10.1002/acm2.70082","DOIUrl":"https://doi.org/10.1002/acm2.70082","url":null,"abstract":"<p><strong>Purpose: </strong>This study aims to evaluate the accuracy of the frameless linear accelerator-based stereotactic radiosurgery (FSRS) system incorporating cone-beam CT (CBCT), six degrees of freedom (6-DoF) couch, room laser, and surface image-guided (SG) systems. It focuses on assessing the FSRS system's accuracy and ability to detect position errors using head phantoms at different couch angles. Turntables were used to simulate the couch rotation to overcome the limitation of the available couch rotation angles for a 360° CBCT scan.</p><p><strong>Methods: </strong>Two head phantoms, each positioned on its respective turntable, were used for measurements, with the turntables placed on the couch. Factors affecting the evaluations of the FSRS system's accuracy were analyzed, including quality assurance (QA) procedures for the SG system, the automatic CBCT-CT registration method, the CBCT clip box volume, and the selected region of interest (ROI) size in the SG system. Discrepancies in isocenter shifts between CBCT and SG systems were measured to evaluate the FSRS system's accuracy and its ability to correct isocenter shifts at different turntable angles. The FSRS system's ability to detect position errors at different turntable angles was also evaluated by introducing ± 2.0 mm translational errors.</p><p><strong>Results: </strong>With the appropriate CBCT-CT registration method and ROI size of the SG system, the accuracy evaluations of the FSRS system indicated average discrepancies between the readouts from the CBCT and the SG system ≤ 0.9 mm/0.8° for the head phantoms. Error simulation demonstrated that the FSRS system was able to detect position errors when 2 mm translational errors were intentionally introduced, with most average discrepancies < 1 mm/1°.</p><p><strong>Conclusion: </strong>This study introduces an innovative approach to quantifying the impact of couch rotation on the FSRS system using head phantoms with turntables. The overall accuracy of the FSRS system was on the order of 1.1 mm/1°.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70082"},"PeriodicalIF":2.0,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143676960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantification and dosimetric impact of intra-fractional bladder changes during CBCT-guided online adaptive radiotherapy for pelvic cancer treatments.","authors":"Ingrid Valencia Lozano, Elizabeth Buss, Catherine S Spina, David P Horowitz, Lisa A Kachnic, Michael Price, Yi-Fang Wang, Reshma Munbodh","doi":"10.1002/acm2.70074","DOIUrl":"https://doi.org/10.1002/acm2.70074","url":null,"abstract":"<p><strong>Purpose: </strong>This study quantitatively evaluates bladder changes and their dosimetric impact during the on-couch adaptive process on a commercial CBCT-based online adaptive radiotherapy (CT-gART) platform.</p><p><strong>Methods: </strong>Data from 183 fractions of ten patients receiving online ART for pelvic cancers were analyzed retrospectively. Bladder contours were automatically generated and revised by an expert for each pair of planning and verification CBCTs. Bladder shape changes were assessed using geometric and boundary distance metrics. A deformable image registration (DIR) workflow was implemented to obtain spatial motion characteristics, validated by the dice similarity coefficient between bladder contours. Dosimetric parameters were quantified by warping 'intended' dose distributions to the verification CBCT anatomy using DIR to evaluate coverage and OAR objectives.</p><p><strong>Results: </strong>Bladder volume changed noticeably during the on-couch adaptation process (19.7 ± 3.3 min). Day-to-day bladder expansion showed an average increase of 3.4 cc/min ± 1.5 cc/min for the full bladder and 0.8 cc/min ± 0.3 cc/min for empty bladder protocols. Deformation occurred mainly in the superior region and was more pronounced for the full bladder protocol. Displacements over 5 mm in cranial-caudal and anterior-posterior directions averaged 16% and 5% of the volume for full bladders and 5% and 4% for empty bladders, respectively. CTV coverage (V100%) was maintained when the bladder was the target, but PTV V95% was reduced by an average of 7%. For non-bladder treatments, bladder constraints increased slightly for supine subjects (0.5 Gy/fx), with prone subjects almost unaffected.</p><p><strong>Conclusions: </strong>A framework using auto-segmentation and DIR was developed to evaluate the intra-fractional motion of the bladder during CTgART. Results suggest that reducing the isotropic PTV margin to less than 7 mm may be feasible for oART, allowing patient-specific anisotropic margins while maintaining the quality of the adaptive plan.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70074"},"PeriodicalIF":2.0,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143669943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling of a double-scattering proton therapy nozzle using the FLUKA Monte Carlo code and analysis of linear energy transfer in patients treated for prostate cancer.","authors":"Rasmus Klitgaard, Lars Fredrik Fjæra, Camilla Hanquist Stokkevåg, Perry Johnson, Mark Artz, Nancy Price Mendenhall, Curtis Bryant, Ludvig Paul Muren","doi":"10.1002/acm2.70032","DOIUrl":"https://doi.org/10.1002/acm2.70032","url":null,"abstract":"<p><strong>Background: </strong>The dose-averaged linear energy transfer (LET_D) in proton therapy (PT) has in pre-clinical studies been linked to the relative biological effectiveness (RBE) of protons. Until recently, the most common PT delivery method in prostate cancer has been double-scattered PT, with LET_D only available through dedicated Monte Carlo (MC) simulations. However, as most studies of the relationship between LET_D and RBE in double scattered PT have been focused on the head and neck region, existing MC implementations have not been capable of calculating LET_D for the longer field ranges used, for example, in the pelvic region.</p><p><strong>Purpose: </strong>The initial aim of this study was to implement a MC code allowing for LET_D calculations in double-scattered PT of prostate cancer. Additionally, we explored LET_D profiles and LET_D as a function of field configuration, by performing MC calculations for a large prostate cancer cohort treated with double-scattered PT.</p><p><strong>Methods: </strong>The components of a passive scattered clinical treatment nozzle used for delivery of extended field ranges, with two associated modulation wheels, were implemented into an existing FLUKA MC framework for LET_D calculations. The code was validated to spread out Bragg peak (SOBP) measurements conducted using the treatment nozzle with 11 different range and modulation width configurations. After validation, LET_D distributions were calculated on the planning computed tomographies of 582 prostate cancer patients treated with two-field double-scattered PT. All patients had symmetric field configurations with respect to the sagittal plane, with one pair of posterior oblique, lateral opposing, or anterior oblique fields. Dose and LET_D volume parameters and the mean LET_D ratio between the bladder and rectum were compared across the three groups.</p><p><strong>Results: </strong>The range differences were below 1 mm for all SOBP scenarios used for calibration. For 9 of 11 SOBP scenarios, the modulation width differences were below 2 mm. For the patient simulations, the mean gamma pass rates (3 mm/3%) were at least 98% in the PTV, bladder, and rectum. Comparing anterior to posterior field configurations, the mean LET_D in the bladder increased within both the 10 and 70 Gy iso-dose regions, and conversely, the mean LET_D decreased for the rectum. There was a marked difference in the mean bladder-to-rectum LET_D ratios between anterior oblique, lateral opposing and posterior oblique field configurations.</p><p><strong>Conclusion: </strong>A MC code allowing for accurate calculations of dose and LET_D in double-scattered PT of prostate cancer was implemented and validated. The LET_D distributions in the rectum and bladder showed a systematic dependence on the field configuration.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70032"},"PeriodicalIF":2.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Position-dependent offset corrections for ring applicator reconstruction in cervical cancer brachytherapy.","authors":"Leon G Aldrovandi, Matthias E T Dessein, Shelley M Pearson, Shelley M Bulling","doi":"10.1002/acm2.70079","DOIUrl":"https://doi.org/10.1002/acm2.70079","url":null,"abstract":"<p><strong>Purpose: </strong>Due to the tight curvature in their design, ring applicators are usually associated with large positioning errors. The standard practice to correct for these deviations based on global offsets may not be sufficient to comply with the recommended tolerance. In this work, we investigate two methods for applicator reconstruction that implement position-dependent source offset corrections.</p><p><strong>Methods: </strong>Measurements were performed using the Varian Interstitial PEEK Ring 60° and a Varian BRAVOS afterloader. Source positioning was characterized by means of autoradiographs acquired for three different loading patterns and three ¹⁹²Ir sources over a period of 5 months. Additionally, the actual source path was determined by means of a series of planar kV images for different dummy cable positions. The first position-dependent correction method consists of locally modifying the radius of the reconstructed source path according to the measured offsets. The second method, recommended by Varian, simulates a bidirectional movement of the source during applicator reconstruction to compensate for positioning errors.</p><p><strong>Results: </strong>Autoradiographs showed a quasi-linear increase of the dwell position offsets, with a negligible error at the tip and a value close to 3 mm at the end of the ring. This result, consistent with a circular wire movement with an effective radius 0.5 mm larger than the nominal value, was in agreement with the observations from the kV images. After implementation of the position-dependent correction methods, residual positioning errors for the two methods resulted in a mean value (±1 SD) of 0.0 (±0.3) mm, and a range of [-0.7 mm, 0.7 mm].</p><p><strong>Conclusion: </strong>The two tested methods for applicator reconstruction with position-dependent source offset corrections were able to successfully correct the positioning errors. The method recommended by the manufacturer had the additional advantages of a more straightforward implementation and the potential for use in other applicator types.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70079"},"PeriodicalIF":2.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stereotactic radiosurgery for multiple small brain metastases using gamma knife versus single-isocenter VMAT: Normal brain dose based on lesion number and size.","authors":"Abram Abdou, Timoteo Almeida, Elizabeth Bossart, Irene Monterroso, Eric A Mellon","doi":"10.1002/acm2.70065","DOIUrl":"https://doi.org/10.1002/acm2.70065","url":null,"abstract":"<p><strong>Purpose: </strong>The study evaluates rapid linear accelerator (Linac) single isocenter stereotactic radiosurgery (SRS) with Hyperarc for large target numbers. We compared to Gamma Knife (GK), which suffers from long treatment times and investigated causes of differences.</p><p><strong>Methods: </strong>Linac SRS and GK treatment plans for patients receiving 18 Gy to the gross tumor volume (GTV) were evaluated for mean brain dose and volume of brain receiving 12 Gy or more (V12 Gy) as toxicity correlates. Further investigations included patient-based and simulations of 1-33 brain metastases to compare the ability of Linac SRS and GK to separate adjacent and distant lesions.</p><p><strong>Results: </strong>For three patients (33, 33, and 18 metastases), GK reduced mean brain dose (2.89 Gy, 2.38 Gy, 2.79 Gy) compared to 2.5 mm microMLCs (4.36 Gy, 4.75 Gy, 4.26 Gy, p = 0.027) and 5 mm MLCs (4.71 Gy, 5.22 Gy, 4.60 Gy, p = 0.024). GK also improved V12 Gy (13.29 cc, 11.62 cc, 33.79 cc) compared to microMLC (25.31 cc, 30.91 cc, 54.71 cc, p = 0.019) and MLC (31.69 cc, 33.68 cc, 54.71 cc). This must be balanced with GK treatment times (5-11 h). GK achieved 50% prescription line separation at smaller distances (1.8-7.6 mm) than microMLC (7.7-10.2 mm) or MLC (8.8-12.2 mm) for 0.5-1.0 cm targets (4-8 mm collimator single shot). For 1.5 cm targets (16 mm shot) results were mixed (GK 5.4-17 mm, microMLC 9.5-11.2 mm, MLC 9.5-11.3 mm). A 7.7 cm simulation cube was then incrementally filled with 0.5 cm or 1.0 cm equidistant targets. GK plan mean brain dose increased 0.04 Gy/target (1.08 Gy mean/27 targets) compared to 0.14 Gy/target for microMLC (3.78 Gy mean/27 targets) for 0.5 cm targets, with differences diminishing for 1.0 cm targets (GK 0.15 Gy/target, microMLC 0.17 Gy/target).</p><p><strong>Conclusions: </strong>For numerous small metastases GK improves dosimetry but has exceedingly long treatment times. GK improves dose separation for adjacent lesions < 1.0 cm and conformity for small (∼0.5 cm) targets. GK and Linac differences are small for individual targets but compound over many targets. V12 Gy limits in the NCIC CE.7 trial protocol mandate dose modifications for Linac SRS but not GK.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70065"},"PeriodicalIF":2.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A systematic review of electron FLASH dosimetry and beam control mechanisms utilized with modified non-clinical LINACs.","authors":"Justin DeFrancisco, Siyong Kim","doi":"10.1002/acm2.70051","DOIUrl":"https://doi.org/10.1002/acm2.70051","url":null,"abstract":"<p><strong>Background: </strong>FLASH has been shown to spare normal tissue toxicity while maintaining tumor control. However, existing irradiation platforms and dosimetry are not compatible. Consequently, an abundance of FLASH delivery devices and new dosimetry across all modalities has been created. Many review articles concluded that dosimetry is modality-dependent. Focusing on electrons, researchers have modified clinical LINACs to enable FLASH dose rates. Modified LINACs caused the development of unique control systems that have yet to be characterized. Improvement could be made when considering the organization of reviews.</p><p><strong>Purpose: </strong>To systematically perform a literature survey on electron FLASH dosimetry and beam control mechanisms with modified LINACs, detail where articles originated, and organize the results.</p><p><strong>Methods: </strong>A literature survey was performed from two websites using specified keywords and sifted results to find articles that fit the criteria. The results were organized in tables and summaries effectively by matching up dosimeters with their measurement goal, referring to their specific models, outlining the irradiation conditions they were tested in, and detailing their calibration procedure. Furthermore, included was the unique topic of control mechanisms.</p><p><strong>Results: </strong>Twenty-eight matches were found. Various dosimeters were examined to measure absorbed dose, beam characteristics (BC), dose per pulse (DPP), and pulse counting (PC). Specific detectors and the irradiation conditions are organized and presented in a table. Each model's pros and cons are presented in another table for further consideration. A third table is provided to detail beam control methods.</p><p><strong>Conclusions: </strong>Dosimetry is majorly film-based for absorbed dose and beam characteristic measurements. Many candidates for dosimeters for the use of DPP and PC have been tested, but they have yet to be tested without limitations. Beam control mechanisms primarily consist of unacceptable delivery errors. Many suggestions for improvement were given, mainly consisting of finding new dosimeters and modulating the dose DPP.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70051"},"PeriodicalIF":2.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Closing the gap in plan quality: Leveraging deep-learning dose prediction for adaptive radiotherapy.","authors":"Sean J Domal, Austen Maniscalco, Justin Visak, Michael Dohopolski, Dominic Moon, Vladimir Avkshtol, Dan Nguyen, Steve Jiang, David Sher, Mu-Han Lin","doi":"10.1002/acm2.70045","DOIUrl":"https://doi.org/10.1002/acm2.70045","url":null,"abstract":"<p><strong>Purpose: </strong>Balancing quality and efficiency has been a challenge for online adaptive therapy. Most systems start the online re-optimization with the original planning goals. While some systems allow planners to modify the planning goals, achieving a high-quality plan within time constraints remains a common barrier. This study aims to bolster plan quality by leveraging a deep-learning dose prediction model to predict new planning goals that account for inter-fractional anatomical changes.</p><p><strong>Methods: </strong>Fine-tuned patient-specific (FT-PS) models were clinically evaluated to accurately predict dose for 23 adaptive fractions of 15 head-and-neck (H&N) patients treated with Ethos ART. The original adapted plan from the adaptive treatment session was used as the quality baseline. Based on physician-approved adaptive treatment contours, the FT-PS model predicted subsequent planning goals for high-impact organs at risk (OARs). These goals were retrospectively re-optimized in Ethos to compare the original adapted plan (IOE-Auto Plan) with the newly re-optimized plan (AI-guided IOE Plan). A physician blindly selected the preferred plan.</p><p><strong>Results: </strong>Dose savings were observed for nine high impact OAR's including the constrictor, ipsilateral/contralateral parotid, ipsilateral/contralateral submandibular gland, oral cavity, and esophagus, mandible and larynx with a maximum value of 5.47 Gy. Of the 23 plans reviewed in the blind observer study, 19 re-optimized plans were chosen over the original adapted session plan.</p><p><strong>Conclusions: </strong>Our preliminary results demonstrate the feasibility of utilizing an AI dose predictor to predict optimal planning goals with anatomical changes, thereby improving adaptive plan quality. This method is feasible for both online and offline adaptive radiotherapy (ART) and has the potential to significantly enhance treatment outcomes for head-and-neck (H&N) cancer patients.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70045"},"PeriodicalIF":2.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of dosimetric and spatial accuracy of a virtual cone technique for radiosurgery using linac-integrated CBCT-based polymer gel dosimetry.","authors":"Tenzin Kunkyab, Michael Lamey, Andrew Jirasek, Michael Kudla, Nathan Becker, Benjamin Mou, Derek Hyde","doi":"10.1002/acm2.70081","DOIUrl":"https://doi.org/10.1002/acm2.70081","url":null,"abstract":"<p><strong>Purpose: </strong>This study evaluates the dosimetric and geometric precision of a virtual cone technique using CBCT-based polymer gel dosimetry, enabling radiation delivery, and imaging readout within an identical spatial coordinate system.</p><p><strong>Methods: </strong>We created a C# script for a virtual cone technique that generates a treatment plan with 10 gantry arcs at 0°, 36°, 72°, 288°, and 324° couch angles, with 2 arcs per couch angle using 45° and 135° collimator angles. Two verification plans using Eclipse v15.6 (AcurosXB) were created with 20 Gy at the maximum dose for: (1) a cylindrical gel, with an additional calibration region; (2) a 3D printed anthropomorphic skull phantom with a gel insert. The 50% isodose (10 Gy) width through the central axis of the axial and sagittal planes (SPs) were measured for the gel experiment. The distance between the centers-of-masses of the 10 Gy isodose region of the plan and the gel (skull phantom) were calculated for an end-to-end spatial accuracy test.</p><p><strong>Results: </strong>The maximum point dose measured with gel was within 1% of the plan, though the gel measured 50% isodose widths of 5.56 <math> <semantics><mrow><mspace></mspace> <mo>±</mo> <mspace></mspace></mrow> <annotation>$; pm ;$</annotation></semantics> </math> 0.02 mm, 5.65  <math> <semantics><mrow><mo>±</mo> <mspace></mspace></mrow> <annotation>$ pm ;$</annotation></semantics> </math> 0.04 mm, 4.23  <math> <semantics><mrow><mo>±</mo> <mspace></mspace></mrow> <annotation>$ pm ;$</annotation></semantics> </math> 0.01 mm for axial (anterior-posterior), axial (left-right), sagittal (superior-inferior) respectively, which were slightly narrower than Eclipse (1.29 mm maximum difference in the SP due to CBCT slice thickness). The center-of-mass distance was 0.66 mm for the gel experiment, and 0.94 mm for complete end-to-end testing with the anthropomorphic phantom, including CBCT setup (kV-MV isocenter uncertainty).</p><p><strong>Conclusion: </strong>The 50% isodose width of the gel measurement was 5.15 mm (mean), which was tighter than our Eclipse v15.6 beam model. The end-to-end spatial accuracy test, only achievable with gel dosimetry using CBCT readout, resulted in sub-millimeter accuracy. This study demonstrates the value of gel dosimetry in verifying the dosimetric and spatial accuracy of this high precision, stereotactic technique.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70081"},"PeriodicalIF":2.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A method for measuring spatial resolution based on clinical chest CT sequence images.","authors":"Ying Liu, Jingying Shen, Haowei Zhang, Haikuan Liu","doi":"10.1002/acm2.70078","DOIUrl":"https://doi.org/10.1002/acm2.70078","url":null,"abstract":"<p><strong>Purpose: </strong>This study aimed to develop and validate a method for characterizing the spatial resolution of clinical chest computed tomography (CT) sequence images.</p><p><strong>Methods: </strong>An algorithm for characterizing spatial resolution based on clinical chest CT sequence images was developed in Matlab (2021b). The algorithm was validated using CT sequence images from a custom-made chest automatic tube current modulation (ATCM) phantom and clinically reconstructed chest CT sequence images. A region of interest (ROI) was automatically established at the edges of CT image subject to calculate the edge spread function (ESF). The ESF curves from consecutive CT images within the same sequence were fitted into a curve, and the line spread function (LSF) was derived through differentiation. A Fourier transformation of the LSF curve was conducted to obtain the modulation transfer function (MTF). The method's effectiveness was verified by comparing the 50% MTF and 10% MTF values with those calculated using IndoQCT (22a) software. The method was also applied to clinical CT images to calculate MTF values for various reconstructions, confirming its sensitivity by determining spatial resolution of clinically reconstructed images.</p><p><strong>Results: </strong>Validation experiments based on the phantom CT sequence images demonstrated that the MTF values calculated using the proposed method had an average difference of within ± 5% compared to the results obtained with IndoQCT. Validation experiments with clinical CT sequence images indicated that the method effectively reflects differences and variations in spatial resolution of images under different reconstruction kernels, with the MTF values for B10f-B50f and D10f-D50f exhibiting a consistent increase.</p><p><strong>Conclusion: </strong>A method for measuring spatial resolution using clinical chest CT sequence images was developed. This method provides a direct means of spatial resolution characterization for clinical CT datasets and a more accurate representation of CT imaging quality, effectively reflects variations across different reconstruction convolution kernels, demonstrating its sensitivity.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70078"},"PeriodicalIF":2.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometric and dosimetric evaluation of a commercial AI auto-contouring tool on multiple anatomical sites in CT scans.","authors":"Robert N Finnegan, Alexandra Quinn, Patrick Horsley, Joseph Chan, Maegan Stewart, Regina Bromley, Jeremy Booth","doi":"10.1002/acm2.70067","DOIUrl":"https://doi.org/10.1002/acm2.70067","url":null,"abstract":"<p><p>Current radiotherapy practices rely on manual contouring of CT scans, which is time-consuming, prone to variability, and requires highly trained experts. There is a need for more efficient and consistent contouring methods. This study evaluated the performance of the Varian Ethos AI auto-contouring tool to assess its potential integration into clinical workflows. This retrospective study included 223 patients with treatment sites in the pelvis, abdomen, thorax, and head and neck regions. The Ethos AI tool generated auto-contours on each patients' pre-treatment planning CT, and 45 unique structures were included across the study cohort. Multiple measures of geometric similarity were computed, including surface Dice Similarity Coefficient (sDSC) and mean distance to agreement (MDA). Dosimetric concordance was evaluated by comparing mean dose and maximum 2 cm³ dose (D_{2 cc}) between manual and AI contours. Ethos AI demonstrated high geometric accuracy for well-defined structures like the bladder, lungs, and femoral heads. Smaller structures and those with less defined boundaries, such as optic nerves and duodenum, showed lower agreement. Over 70% of auto-contours demonstrated a sDSC > 0.8, and 74% had MDA < 2.5 mm. Geometric accuracy generally correlated with dosimetric concordance, however differences in contour definitions did result in some structures exhibiting dose deviations. The Ethos AI auto-contouring tool offers promising accuracy and reliability for many anatomical structures, supporting its use in planning workflows. Auto-contouring errors, although rare, highlight the importance of ongoing QA and expert manual oversight.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70067"},"PeriodicalIF":2.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143648641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}