Journal of Applied Clinical Medical Physics最新文献

{"title":"Surface dose analysis and dosimetric comparison of Halcyon versus Truebeam in breast cancer radiotherapy: An OSL dosimetry study.","authors":"Mustafa Çağlar, Kudret Akçay, Esra Serin, Dursun Eşitmez, Mehmet Sıddık Cebe, Navid Kheradmand, Ömer Yazıcı, Dilek Ünal, Evrim Metcalfe","doi":"10.1002/acm2.70085","DOIUrl":"https://doi.org/10.1002/acm2.70085","url":null,"abstract":"<p><strong>Purpose: </strong>Breast cancer is a neoplastic disease with high prevalence among women. Radiotherapy is one of the principal treatment modalities for this disease, but it poses significant challenges. This study aimed to compare and evaluate the technical and dosimetric performance of conventional C-arm linac systems and a new design, Halcyon, in the context of breast radiotherapy.</p><p><strong>Methods: </strong>The study included ten patients who had undergone left breast radiotherapy. Additionally, breast radiotherapy was simulated with an anthropomorphic phantom, and similar planning studies were performed. A total of 40 treatment plans were prepared for ten patients using the field-in-field (FinF) and volumetric modulated arc therapy (VMAT) techniques on both TrueBeam and Halcyon systems. Subsequently, treatment plans were created for anthropomorphic phantoms using both techniques on both devices. The dosimetric comparisons were conducted on treatment plans with different treatment techniques on both devices. An anthropomorphic phantom was employed to ascertain the surface dose during treatment, with irradiation conducted in the following with the OSL dosimetry method.</p><p><strong>Results: </strong>Patient plan comparisons showed no statistically significant differences in planning target volume (PTV) outcomes between techniques and devices. Upon analysis of the organ at risk (OAR), statistically significant differences were identified for FinF in both devices for low-dose regions. Analysis of the OSL results obtained from phantom irradiations revealed that the Halcyon results were higher than those obtained with the TrueBeam for both techniques. Additionally, a comparison of OSL results with the TPS data revealed discrepancies of up to 18% within the field and up to 22% outside the field. Furthermore, Halcyon demonstrated higher Monitor Unit (MU) values for both techniques, while still maintaining shorter treatment times.</p><p><strong>Conclusion: </strong>The Halcyon demonstrated comparable technical and dosimetric outcomes to conventional C-arm linac in breast radiotherapy. Its distinctive design features contribute to the implementation of efficient and secure treatment modalities.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70085"},"PeriodicalIF":2.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143779899","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":"Assessment of a medical physics educational program for science teachers","authors":"Ashley J. Cetnar,&nbsp;Jeffrey Woollard,&nbsp;Lin Ding","doi":"10.1002/acm2.70087","DOIUrl":"10.1002/acm2.70087","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Introduction</h3>\u0000 \u0000 <p>Medical physics is a fulfilling profession where physics is applied to advance human health. However, many are uninformed of the role of physicists in medicine, and students are unaware of this career pathway. This study presents a pilot 1-year program for science teachers to learn about physics in medicine and share with students and teachers.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A cohort of middle school and high school science teachers were selected to learn about physics in medicine, develop lesson plans for their students, participate in a Physics in Medicine field trip hosted at a cancer hospital, and concluded with a professional development day for other regional science teachers. Surveys were conducted throughout the program to assess attitudes toward teaching medical physics, content knowledge of medical physics, collaboration, and demographic information from participants.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The program was implemented over the course of a year which included 5 school districts, 10 science teachers, and hundreds of students. After participating in the program, teacher scores on surveys regarding attitudes toward teaching medical physics and content knowledge significantly increased for the cohort. Strong collaboration between teaching pairs was maintained throughout the program based on survey responses. Teachers participating in the 1-day professional development program also benefited from the program based on survey responses regarding attitudes toward medical physics and interest in learning more about medical physics.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>This pilot study demonstrated the feasibility and effectiveness of an educational model for teachers’ understanding and connecting medical physics with students in their schools.  The program was well received by teachers and students, and this manuscript provides guidelines for effective replication of the curriculum at other institutions.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 5","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70087","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143779892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An extension to the OVH concept for knowledge-based dose volume histogram prediction in lung tumor volumetric-modulated arc therapy.","authors":"Johann Brand, Juliane Szkitsak, Oliver J Ott, Christoph Bert, Stefan Speer","doi":"10.1002/acm2.70090","DOIUrl":"https://doi.org/10.1002/acm2.70090","url":null,"abstract":"<p><strong>Purpose: </strong>Volumetric-modulated arc therapy (VMAT) treatment planning allows a compromise between a sufficient coverage of the planning target volume (PTV) and a simultaneous sparing of organs-at-risk (OARs). Particularly in the case of lung tumors, deciding whether it is possible or worth spending more time on further improvements of a treatment plan is difficult. Therefore, this work aims to develop a knowledge-based, structure-dependent, automated dose volume histogram (DVH) prediction module for lung tumors.</p><p><strong>Methods: </strong>The module is based on comparing geometric relationships between the PTV and the surrounding OARs. Therefore, treatment plan and structure data of 106 lung cancer cases, each treated in 28 fractions and 180 cGy/fx, were collected. To access the spatial information, a two-dimensional metric named overlap volume histogram (OVH) was used. Due to the rotational symmetry of the OVH and the typically coplanar setup of the VMAT technique, OVH is complemented by the so-called overlap-z-histogram (OZH). A set of achievable DVHs is predicted by identifying plans in the database with similar OVH and OZH. By splitting the dataset into a test set of 22 patients and a training set of 84 patients, the prediction capability of the OVH-OZH combination was evaluated. For comparison between the predicted and achieved DVH curves the coefficient of determination R² was calculated.</p><p><strong>Results: </strong>The total lung showed strong linearity between predicted and achieved DVH curves for the OVH-OZH combination, resulting in a <math> <semantics><msup><mi>R</mi> <mn>2</mn></msup> <annotation>${R^2}$</annotation></semantics> </math> value close to 1 (0.975 ± 0.022). The heart benefits the most of the OZH resulting in a high prediction capability, with a higher <math> <semantics><msup><mi>R</mi> <mn>2</mn></msup> <annotation>${R^2}$</annotation></semantics> </math> of 0.962 ± 0.036 compared to the prediction with OVH only (0.897 ± 0.087).</p><p><strong>Conclusion: </strong>The combination of OZH and OVH was suitable for building a knowledge-based automated DVH prediction module. Implementing this method into the clinical workflow of treatment planning will contribute to advancing the quality of VMAT plans.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70090"},"PeriodicalIF":2.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143779891","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":"BreastWatch: A Varian Eclipse script tool for Community-Based automatic evaluation of breast treatment plans.","authors":"Stefano Agostinelli, Daniele Zefiro, Stefania Garelli, Francesca Cavagnetto, Marco Gusinu, Monica Bevegni, Gladys Blandino, Alessandra Fozza, Fabrizio Levrero","doi":"10.1002/acm2.70080","DOIUrl":"https://doi.org/10.1002/acm2.70080","url":null,"abstract":"<p><strong>Purpose: </strong>This work introduces BreastWatch, a Varian Eclipse script tool designed to help medical physicists, dosimetrists, and radiation oncologists easily inspect and improve External Beam Breast Treatment (EBBT) plans using automatic evaluation of protocol dose-constraints enhanced by a Community-Based approach.</p><p><strong>Methods: </strong>BreastWatch examines Eclipse EBBT Plans and Plan Sums, automatically testing the plan's DVH against built-in international EBBT protocol (NRG RTOG1005, ICR Fast-Forward, ICR FAST, and EUROPA 1.2) dose-constraints. Results are displayed using traffic lights and an overall BW-SCORE. To overcome protocol dose-constraints limitations, the script can export plan data and dose values in CSV format to build a Community-Based Plan Library. These data are automatically read back in BreastWatch to check plans against the statistical distribution of similar Community plans and compute a CB-SCORE, which complements the protocol-based BW-SCORE. In this paper, BreastWatch v.1.6.5.0 script's design and strengths are examined and discussed, after extensive testing with more than 800 EBBT plans by six experienced planners. In a preliminary analysis, the usefulness of the CB approach is investigated by examining the chronological series of two dose-constraints values (Contra-Lung V3Gy and Heart Average Dose) before and after its introduction in BreastWatch.</p><p><strong>Results: </strong>We found BreastWatch to speed up the EBBT planning process, while at the same time helping to improve the treatment plans in terms of PTVs coverage and uniformity, sparing of OARs, consistency, and robustness among different planners. The preliminary analysis of the chronological series of two dose-constraints values for a subgroup of 68 EBBT plans shows a trend (p-value = 0.07) for values to be improved and more consistent after the CB approach introduction.</p><p><strong>Conclusions: </strong>The BreastWatch script is a useful tool for the automatic evaluation of Eclipse EBBT plans. BreastWatch and its Community-Based features have been found to be a simple but effective automation approach to improve the EBBT planning process.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70080"},"PeriodicalIF":2.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143763845","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":"Toward a human-centric co-design methodology for AI detection of differences between planned and delivered dose in radiotherapy.","authors":"Luca M Heising, Frank Verhaegen, Stefan G Scheib, Maria J G Jacobs, Carol X J Ou, Viola Mottarella, Yin-Ho Chong, Mariangela Zamburlini, Sebastiaan M J J G Nijsten, Ans Swinnen, Michel Öllers, Cecile J A Wolfs","doi":"10.1002/acm2.70071","DOIUrl":"https://doi.org/10.1002/acm2.70071","url":null,"abstract":"<p><strong>Introduction: </strong>Many artificial intelligence (AI) solutions have been proposed to enhance the radiotherapy (RT) workflow, but limited applications have been implemented to date, suggesting an implementation gap. One contributing factor to this gap is a misalignment between AI systems and their users. To address the AI implementation gap, we propose a human-centric methodology, novel in RT, for an interface design of an AI-driven RT treatment error detection system.</p><p><strong>Methods: </strong>A 5-day design sprint was set up with a multi-disciplinary team of clinical and research staff and a commercial company. In the design sprint, an interface was prototyped to aid medical physicists in catching treatment errors during daily treatment fractions using dose-guided RT (DGRT) with a portal imager.</p><p><strong>Results: </strong>The design sprint resulted in a simulated prototype of an interface supported by all stakeholders. Important features of an interface include the AI certainty metric, explainable AI features, feedback options, and decision aid. The prototype was well-received by expert users.</p><p><strong>Conclusion/discussion: </strong>Using a co-creation strategy, which is a novel approach in RT, we were able to prototype a novel human-interpretable interface to detect RT treatment errors and aid the DGRT workflow. Users showed confidence that the overall design method and the proposed prototype could lead to a viable clinical implementation.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70071"},"PeriodicalIF":2.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143752739","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":"In vivo transit dosimetry methodology for whole breast intensity modulated radiation therapy","authors":"Lucia Zirone,&nbsp;Elisa Bonanno,&nbsp;Giuseppina R. Borzì,&nbsp;Nina Cavalli,&nbsp;Alessia D'Anna,&nbsp;Andrea Girlando,&nbsp;Martina Pace,&nbsp;Giuseppe Stella,&nbsp;Carmelo Marino","doi":"10.1002/acm2.70072","DOIUrl":"10.1002/acm2.70072","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>In vivo transit dosimetry using an electronic portal imaging device (EPID-IVTD) is an important tool for verifying the accuracy of radiation therapy treatments. Despite its potential, the implementation of EPID-IVTD in breast intensity modulated radiation therapy (IMRT) treatments has not yet been standardized, limiting its clinical adoption. A standardized EPID-IVTD method could enhance treatment accuracy and improve patient safety in routine clinical practice.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aims to develop a method for EPID-IVTD for whole breast IMRT treatment.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Gamma passing rates (GPRs) analysis was the basis of the work conducted on a dataset of 50 patients. The first phase of the work focused on the identification of the reference fraction. In the second phase a method for performing EPID-IVTD was implemented. Lower-tolerance and -action limits (l-TL and l-AL), as introduced by AAPM TG 218, were employed to determine the reference fraction and used as alert and alarm thresholds, respectively, in EPID-IVTD monitoring.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The first treatment fraction demonstrated the best dosimetric agreement with the theoretical plan and was therefore used as the reference in the second phase of the study. EPID-IVTD results showed that 75% of the GPRs ranged from 97.5% to 99.9%, 93.83% were above the l-TL, 4.31% fell between l-TL and l-AL, and 1.86% were below l-AL.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>A method for the implementation of an effective EPID-IVTD in whole breast IMRT treatment was developed and is now routinely applied at our center, enabling efficient monitoring in clinical practice.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 5","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70072","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143709594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shielding resources for four common radiopharmaceuticals utilized for imaging and therapy: Tc-99m, F-18, I-131, and Lu-177","authors":"Michael Oumano,&nbsp;Richard Wendt,&nbsp;James Botti,&nbsp;Nathan Busse,&nbsp;David Hintenlang,&nbsp;Stephanie Leon,&nbsp;Kevin Little,&nbsp;Melissa Martin,&nbsp;Richard Massoth,&nbsp;Kenneth Matthews,&nbsp;Rameshwar Prasad,&nbsp;Sharon White,&nbsp;Jessica Clements","doi":"10.1002/acm2.70084","DOIUrl":"10.1002/acm2.70084","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Introduction</h3>\u0000 \u0000 <p>The use of radioactive materials in the United States has been tightly regulated by the Nuclear Regulatory Commission and other entities for many decades. In 2015, however, the Joint Commission began to require hospital-based nuclear medicine departments to conduct shielding designs and evaluations for radioactive material areas, mirroring established x-ray practices. NCRP Report No. 147 guides diagnostic medical x-ray shielding, but obviously cannot be used alone for nuclear medicine applications. The rising demand for theranostic nuclear medicine shielding evaluations particularly necessitates updated focused guidance, the aim of this report.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Monte Carlo simulations were conducted using GATE software to analyze the effects of various barriers on the transmission of radioactive emissions. The simulations used point sources of Tc-99m, F-18, I-131, and Lu-177 and evaluated dose deposition to blocks of tissue using Dose Actors. Different ceiling heights (ranging from 10–16 feet) were also tested for scattering effects. The Archer equation was employed to fit transmission curves and estimate required barrier thicknesses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Broad beam transmission factors and Archer fitting parameters are reported for various materials including lead, gypsum, concrete (light weight and normal weight), glass, and steel. A sample shielding calculation is provided for a wall separating Lu-177 dotatate patients from an adjacent office to maintain public dose limits. Relevant occupancy factors are also provided.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>While Lu-177 has a relatively low exposure rate constant, shielding may be necessary for high-volume therapies like Lu-177 DOTATATE and Lu-177 vipivotide tetraxetan PSMA. Shielding involves accounting for broad radiation beams and requires thorough characterization of radiation buildup. When shielding to the typical height of 7 feet, scatter from ceilings and floors is negligible for transmission above 10%, but severely limits the ability to shield for transmission below 1%.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 5","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143700408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"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}