Journal of Applied Clinical Medical Physics最新文献

{"title":"Machine stability and dosimetry for ultra-high dose rate FLASH radiotherapy human clinical protocol","authors":"Patrik Gonçalves Jorge,&nbsp;Reiner Geyer,&nbsp;Rémy Kinj,&nbsp;Luis Schiappacasse,&nbsp;Wendy Jeanneret-Sozzi,&nbsp;Jean Bourhis,&nbsp;Fernanda Herrera,&nbsp;François Bochud,&nbsp;Claude Bailat,&nbsp;Raphaël Moeckli","doi":"10.1002/acm2.70102","DOIUrl":"10.1002/acm2.70102","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The FLASH effect, induced by ultra-high dose rate (UHDR) irradiations, offers the potential to spare normal tissue while effectively treating tumors. It is important to achieve precise and accurate dose delivery and to establish reliable detector systems, particularly for clinical trials needed to help the clinical transfer of FLASH-Radiotherapy (FLASH-RT). However, the use of monitoring chambers with UHDR beams is presently limited, leading to the reliance on passive dosimetry and machine stability.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aimed to investigate the energy and output stability of a UHDR Mobetron (IntraOp, USA) and to compare it with its conventional dose rate (CDR) mode. Furthermore, we assessed the dosimetric accuracy of a human clinical protocol for FLASH-RT.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Over a 26-month duration, we assessed the short- and long-term stability of the output and energy of the Mobetron system. Daily checks were conducted for 9 MeV CDR and UHDR. In parallel, the IMPulse clinical trial involving patients with skin metastases from melanoma was initiated. Prescription doses ranging from 22 to 28 Gy were administered. Pre-, post-, and <i>in vivo</i> dosimetry using alanine and thermoluminescent dosimeters (TLDs) was performed and compared to the prescription doses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Short-term output fluctuations remained below 0.6 % and 1 % for 9 MeV CDR and UHDR, respectively. Long-term output fluctuations were within 2 % and the long-term energy fluctuations were below 2 mm (R₅₀) for both modes. The delivered doses of the IMPulse trial showed deviations below 4 % compared to prescription doses for all patients.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The Mobetron system demonstrated favorable short- and long-term stability. There was a good agreement between the prescribed and the measured dose for the clinical IMPulse trial. The stability of this UHDR machine allows us to effectively conduct human clinical protocols as well as preclinical experiments, even in the absence of a real-time monitoring system.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70102","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144007183","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":"Improving dose delivery in non-coplanar cranial SRS: Stereoscopic x-ray-guided mitigation of table walkout errors","authors":"Yohan A. Walter,&nbsp;Philip F. Durham,&nbsp;Anne N. Hubbard,&nbsp;William E. Burrell,&nbsp;Hsinshun T. Wu","doi":"10.1002/acm2.70099","DOIUrl":"10.1002/acm2.70099","url":null,"abstract":"<div>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Linear accelerator (LINAC)-based single-isocenter multi-target (SIMT) treatment has streamlined the cranial stereotactic radiosurgery (SRS) workflow. Though efficient, SIMT delivery adds additional challenges that should be considered, including increased sensitivity to rotational errors for off-isocenter targets. Room-mounted imaging systems carry the advantage of allowing fast, low-dose imaging at nonzero couch angles, which may combat the effects of table walkout and residual rotational errors. Here, we performed a series of end-to-end tests to determine if these corrections correlate with a measurable difference in delivered dose and to assess the overall accuracy of SIMT delivery on our LINAC-based SRS platform.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Ten treatment plans of increasing complexity were created in the Elements 4.0 treatment planning system (TPS, Brainlab AG). Plans were delivered on an Elekta Versa HD LINAC (Elekta AB) with the ExacTrac (ETX) imaging system (Brainlab AG). A CT scan of a StereoPHAN with SRS MapCHECK (Sun Nuclear) was imported into the TPS. Measured targets were contoured on the detector plane. Plans used 4–15 treatment arcs and 4–6 couch angles. ETX was used for initial phantom positioning. Dose measurements were performed for each plan with and without ETX-guided corrections at all table angles.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Translational and rotational residual shifts were all submillimeter and ≤1.0 degrees, respectively, across all table angles. Using 3.0%/1.0 mm gamma criteria, all gamma pass rates (GPR) were either equal or improved when ETX shifts were executed, though the difference was not statistically significant (<i>p</i> = 0.076). However, using 2.0%/0.5 mm criteria, GPR improved significantly (<i>p</i> = 0.016) with ETX repositioning. The average GPR improvement was 4.5% ± 4.8%.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Results demonstrate that repositioning corrections at each table angle improve agreement between planned and delivered dose at the submillimeter level. The test treatment plans in this study may be used for assessment of end-to-end treatment delivery accuracy for complex LINAC-based stereotactic radiotherapy procedures.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70099","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144014969","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":"A Python package for fast GPU-based proton pencil beam dose calculation","authors":"Mahasweta Bhattacharya,&nbsp;Calin Reamy,&nbsp;Heng Li,&nbsp;Junghoon Lee,&nbsp;William T. Hrinivich","doi":"10.1002/acm2.70093","DOIUrl":"10.1002/acm2.70093","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Open-source GPU-based Monte Carlo (MC) proton dose calculation algorithms provide high speed and unparalleled accuracy but can be complex to integrate with new applications and remain slower than GPU-based pencil beam (PB) methods, which sacrifice some physical accuracy for sub-second plan calculation. We developed and validated a Python package implementing a GPU-based double Gaussian PB algorithm for intensity-modulated proton therapy (IMPT) planning research applications requiring a simple, widely compatible, and ultra-fast proton dose calculation solution.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Beam parameters were derived from pristine Bragg peaks generated with MC for 98 energies in our clinical treatment planning system (TPS). We validated the PB approach against measurements by comparing lateral spot profiles (using single-Gaussian sigma) and proton ranges (using R80) for pristine Bragg peaks, as well as spread-out Bragg peaks (SOBPs) in water. Further comparisons of PB and MC from the TPS were performed in a heterogeneous digital phantom and patient plans for four cancer sites using 3D gamma passing rates and dose metrics.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The PB algorithm enabled dose calculation following a single Python import statement. Mean ± standard deviation (SD) errors in sigma, R80, and SOBP dose were 0.05 ± 0.01, 0.0 ± 0.1 mm, and 0.4 ± 1.1%, respectively. Mean ± SD patient plan computation time was 0.28 ± 0.07 s for PB versus 4.68 ± 2.68 s for MC. Mean ± SD gamma passing rate at 2%/2 mm criteria was 96.0 ± 5.1%, and the mean ± SD percent difference in dose metrics was 0.5 ± 3.6%. PB accuracy degraded beyond bone and lung boundaries, characterized by inaccuracies in lateral proton scatter.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>We developed a GPU-based proton PB algorithm compiled as a Python package, providing simple beam modeling, interface, and fast dose calculation for IMPT plan optimization research and development. Like other PB algorithms, accuracy is limited in highly heterogeneous regions such as the thorax.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70093","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144018787","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":"DICOM attribute manipulation tool: Easily change frame of reference, series instance, and SOP instance UID","authors":"Brian M. Anderson,&nbsp;Casey Bojechko","doi":"10.1002/acm2.70104","DOIUrl":"10.1002/acm2.70104","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>In radiation oncology, the integration and registration of multiple imaging modalities is a crucial aspect of the diagnosis and treatment planning process. These images are often inherently registered, a useful feature in most cases, but possibly a hindrance when registration modifications are required. To break this registration requires expert knowledge of file structure or specialized software, posing challenges, and potential errors in accidentally or unnecessarily changing other attributes. Barring these changes, the clinic would have to make do with imprecise registrations which compound overall treatment uncertainty.</p>\u0000 \u0000 <p>To address these issues, we present a novel tool designed to simplify the task of changing three often edited attributes: the frame of reference, the series instance unique identifier (UID), and the SOP instance UID. The tool features an intuitive user interface that empowers practitioners, regardless of their expertise, to effortlessly modify these three commonly edited values.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Validation methods</h3>\u0000 \u0000 <p>Publicly available brain MRI and TCI lung 4DCT images were used to evaluate the software. The ability to change the frame of reference, series instance identifier, and SOP instance identifier using the program was evaluated with both the RayStation treatment planning system and MIM.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Software format and usage notes</h3>\u0000 \u0000 <p>The program is written in C#, easily distributed via GitHub and is compatible with any Windows computer with .NET 4.8 (the standard as of 2023).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Potential applications</h3>\u0000 \u0000 <p>This innovation holds promise for improving the overall workflow efficiency and safety within radiation oncology and radiology, where breaking the frame of reference or changing the series/SOP UIDs is a common occurrence.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70104","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144019752","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":"Design and validation of a novel dosimetry phantom for motion management audits","authors":"Alex Burton,&nbsp;Sabeena Beveridge,&nbsp;Nicholas Hardcastle,&nbsp;Silvio Malfitana,&nbsp;Janaka Madamperuma,&nbsp;Rick Franich","doi":"10.1002/acm2.70091","DOIUrl":"10.1002/acm2.70091","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>We present a novel phantom design for conducting end-to-end dosimetry audits for respiratory motion management of two anatomical treatment sites. The design enables radiochromic film measurements of the dose administered to the target throughout the respiratory cycle (motion-included) and the dose delivered to the time-averaged motion of the phantom (motion-excluded) to be conducted simultaneously.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To demonstrate the phantom's utility in a dosimetry audit and capacity to detect errors by quantifying spatial and dosimetric reproducibility.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Spatial and dosimetric reproducibility was quantified by repeat exposures using a simple lateral beam. Five exposures per measurement configuration were used. In each series of five measurements, the median film was used as the series reference to quantify the reproducibility of the remaining “test films.” Spatial reproducibility was quantified by comparing the position of isodose lines in two axes on the test films back to the series reference. Dosimetric reproducibility was quantified using gamma comparison between each test film and the series reference. Proof-of-concept of the motion-excluded measurement capability was also established by comparing all films to treatment planning system (TPS) calculated dose distributions.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Spatial reproducibility was better than 1 mm on all assessed metrics across all measurements. Film-to-film local gamma passing rates at 3%/0.6 mm were above 90% for all measurements. Film-to-TPS global gamma passing rates at 3%/1 mm were &gt;95% in the motion-excluded measurement series’, but &lt;80% in the motion-included series, highlighting the utility of the motion-excluded measurements.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Measurements were highly reproducible and of sufficient accuracy/reproducibility to facilitate multiple avenues of analysis in a prospective dosimetry audit. Motion-excluded measurements were directly comparable to the TPS dose distribution. Motion-included measurements may yield more clinically-relevant information about the actual dose administered to the target. This promises greater sensitivity to motion management-related errors, detectable in the setting of a dosimetry audit for motion management.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70091","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144025462","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 investigation into the feasibility and efficacy of stereotactic radiosurgery for 1–3 cm single brain lesions on the ring-mounted Halcyon LINAC","authors":"Kate Hazelwood,&nbsp;Shane McCarthy,&nbsp;Josh Misa,&nbsp;David Castelvetere,&nbsp;William St. Clair,&nbsp;Damodar Pokhrel","doi":"10.1002/acm2.70105","DOIUrl":"10.1002/acm2.70105","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;An evaluation of the accuracy, safety, and efficiency of the Halcyon ring delivery system (RDS) for stereotactic radiosurgery (SRS) treatment to relatively small (1–3 cm) brain lesions.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;After completing the extensive in-house quality assurance checks including Winston–Lutz test and independent dose verification via MD Anderson IROC SRS head phantom irradiation on Halcyon, fifteen brain SRS patients previously treated with a single dose of 20 Gy on TrueBeam (6MV-FFF) with HyperArc geometry were retrospectively replanned on Halcyon (6MV-FFF). Plan quality metrics including conformity index (CI), gradient index (GI), gradient distance (GD), PTV coverage, gross tumor volume (GTV) dose, heterogeneity index (HI), and doses to organs-at-risk (OAR) including normal brain dose were evaluated. Patient-specific quality assurance (PSQA) and independent dose verification via in-house Monte Carlo (MC) 2nd checks were performed.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The Halcyon was able to provide highly conformal brain SRS plans. When compared to TrueBeam, CI, planning target volume (PTV) coverage, GTV dose (mean and minimum), HI, and doses to brainstem, optic pathway, and cochlea were statistically insignificant. Statistically significant increases in GI (3.76 vs. 3.25, &lt;i&gt;p&lt;/i&gt; &lt; 0.001), GD (0.56 cm vs. 0.48 cm, &lt;i&gt;p&lt;/i&gt; = 0.001), and V&lt;sub&gt;12Gy&lt;/sub&gt; (5.5 cc vs. 4.6 cc, &lt;i&gt;p&lt;/i&gt; = 0.014), on average using Halcyon versus TrueBeam was found, albeit clinically acceptable values for the majority of brain SRS cases. Halcyon plans provided statistically insignificant maximum dose to most adjacent OARs, though there was a statistically significant decrease in the maximum dose to the spinal cord (0.1 Gy vs. 0.4 Gy, &lt;i&gt;p&lt;/i&gt; = 0.009). Halcyon beam-on time increases by a factor of ∼2 (&lt;i&gt;p&lt;/i&gt; &lt; 0.001). However, the faster patient setup on Halcyon results in a comparable estimated overall treatment time for both platforms. Plan deliverability and accuracy was ensured with PSQA (&gt; 95% pass rate for 2%/2 mm clinical gamma criteria) results and MC 2nd check agreement within ± 5.0%.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Halcyon brain SRS plans provided a similar plan quality compared to HyperArc plans, although it demonstrated an inferior intermediate dose fall off thus slightly higher V&lt;sub&gt;12Gy&lt;/sub&gt;. This study suggests that Halcyon provides acceptable treatment for solitary relatively small brain lesions of 1–3 cm in diameter. Treatment of select patients on ","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70105","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144019620","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":"Comprehensive clinical evaluation of novel 4DCT-based lung function imaging methods","authors":"Ehsan Golkar,&nbsp;Taindra Neupane,&nbsp;Lydia Wilson,&nbsp;Jennifer Kwak,&nbsp;Richard Castillo,&nbsp;Edward Castillo,&nbsp;Yevgeniy Vinogradskiy","doi":"10.1002/acm2.70088","DOIUrl":"10.1002/acm2.70088","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Methods have been developed that apply image processing to 4DCTs to generate 4DCT-ventilation/perfusion lung imaging. Traditional methods for 4DCT-ventilation rely on Hounsfield-Unit (HU) density-change methods and suffer from poor numerical robustness while not providing 4DCT-perfusion data. The purpose of this work was to evaluate the clinical differences between classic HU-based 4DCT-ventilation approaches and novel 4DCT-ventilation/perfusion approaches.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Data from 63 lung cancer patients enrolled in a functional avoidance clinical trial were analyzed. 4DCT-data were used to generate four lung-function images: (1) classical HU-based 4DCT-ventilation (“4DCT-vent-HU”), and three novel, statistically robust methods: (2) 4DCT-ventilation based on the Mass Conserving Volume Change (“4DCT-vent-MCVC”), (3) 4DCT-ventilation using the Integrated Jacobian Formulation, and (4) 4DCT-perfusion. A radiologist reviewed all images for ventilation/perfusion defects (scored as yes/no) and the scores for the novel approaches were compared to those of 4DCT-vent-HU using receiver operating characteristic (ROC) analysis. Functional contours were generated using thresholding methods, and the contours from the three novel 4DCT-ventilation methods were compared against that from 4DCT-vent-HU (Dice similarity coefficients [DSC]). Functional mean lung dose (fMLD) and dose-function metrics were compared against dose-function metrics using 4DCT-vent-HU.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;ROC analysis revealed accuracy in the range of 0.55 to 0.73 comparing radiologist interpretations of 4DCT-vent-HU against the three novel approaches. Average DSC values were 0.41 ± 0.19, 0.44 ± 0.16, and 0.42 ± 0.17 comparing 4DCT-vent-HU to 4DCT-vent-IJF, 4DCT-vent-MCVC, and 4DCT-perf, respectively. All novel imaging methods showed significant differences (&lt;i&gt;p&lt;/i&gt; &lt; 0.01) in dose-function metrics compared to those of 4DCT-vent-HU. 4DCT-vent-MCVC and 4DCT-Perf depicted the smallest and largest differences from 4DCT-vent-HU in fMLD (3.51 ± 3.20 Gy and 5.90 ± 5.29 Gy, respectively).&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusion&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;This is the first work to comprehensively compare novel 4DCT-ventilation/perfusion methods against classical formulations. Our data show that significant differences between the 4DCT-based functional imaging methods exist, suggesting that studies are needed to evaluate which methods provide the most robust clinical results.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 &lt;/div","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70088","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143811410","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":"Log file-based quality assurance method for respiratory gating system.","authors":"Wonjoong Cheon, Young Kyu Lee, Yunji Seol, Chan-Beom Park, Hong Qi Tan, Kyu Hye Choi, Young-Nam Kang, Byung Ock Choi","doi":"10.1002/acm2.70101","DOIUrl":"https://doi.org/10.1002/acm2.70101","url":null,"abstract":"<p><strong>Background: </strong>As medical linear accelerator technology advances, enabling higher dose rate deliveries, hypofractionation regimens has increased. This necessitates respiratory gating systems that synchronize radiation delivery with tumor position, requiring simple rigorous quality assurance (QA) to ensure treatment accuracy and patient safety.</p><p><strong>Purpose: </strong>This study aimed to propose log-based QA for respiratory-gated radiation therapy using the respiratory gating system and treatment machine.</p><p><strong>Methods: </strong>4D CT scans were performed with a Varian motion phantom using a Varian Respiratory Gating for Scanner (RGSC). A treatment plan using 25%-75% respiratory phases with 100 MU was created and delivered to a solid water phantom. Treatment logs containing respiratory signals, beam on/off flags, and frame information were extracted from the treatment planning system's offline review. Log file analyses were conducted using in-house softwares to assess temporal synchronization between respiratory phases and beam triggers. Output measurements using a calibrated ion chamber (FC65G) were performed to evaluate dosimetric accuracy. Additionally, EPID images were acquired in cine mode and analyzed frame-by-frame to independently verify beam delivery timing.</p><p><strong>Results: </strong>Log file analysis revealed precise temporal synchronization, with mean time differences of 0.03 s ± 0.05 s between the planned 25% phase and beam-on, and -0.04 s ± 0.05 s between 75% phase and beam-off. The log-derived beam-on duration (2.61 s ± 0.02 s) closely matched the planned duration (2.66 s ± 0.00 s). Three-month log data showed consistent temporal accuracy, with trigger-on times remaining stable at 2.60 s ± 0.01 s across all measurements. Supporting ion chamber measurements confirmed dosimetric agreement between gating and non-gating modes (difference: 0.05 cGy ± 0.09 cGy) CONCLUSIONS: The proposed log file-based QA method demonstrated high accuracy and reproducibility in assessing respiratory gating performance. This approach provides an efficient, objective method for standardizing QA procedures in respiratory-gated radiation therapy, enhancing treatment accuracy and patient safety.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70101"},"PeriodicalIF":2.0,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803294","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":"Development of a generic focal spot measurement method suitable for bore-type linacs","authors":"Hidetoshi Shimizu,&nbsp;Kazuharu Nishitani,&nbsp;Tomoki Kitagawa,&nbsp;Koji Sasaki,&nbsp;Takahiro Aoyama,&nbsp;Takeshi Kodaira","doi":"10.1002/acm2.70077","DOIUrl":"10.1002/acm2.70077","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>In linear accelerators, deviations in the x-ray focal spot position significantly affect the accuracy of radiation therapy. However, as the focal spot position in bore-type linac systems such as the Radixact system, cannot be assessed using conventional methods, a new evaluation method is required. This study aimed to develop a novel method to measure the focal spot position of Radixact and evaluate any deviations from the ideal x-ray focal spot position.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A structurally simplified measurement system was developed to evaluate the focal spot position of the Radixact system. This system consisted of a vertically aligned metal bar and an ionization chamber, which was moved stepwise to acquire the beam profiles. The focal spot position deviation was calculated based on the center differences of the profiles obtained from two different upstream and downstream locations of the metal bar.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The measurement results indicated that the focal spot position shift was 0.42 mm and −0.36 mm at the target height in the IEC-X and -Y directions, respectively. The measurement uncertainty was 0.187 mm, confirming a slight deviation from the ideal focal position.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study developed a novel method to accurately evaluate the x-ray focal spot position of the Radixact system, which can potentially be applied to other conventional linear accelerators and bore-type systems, such as Halcyon, to improve the accuracy of radiotherapy. However, its generalizability and applicability to different radiotherapy machines must be explored further.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 5","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70077","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803291","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":"Open-source deep-learning models for segmentation of normal structures for prostatic and gynecological high-dose-rate brachytherapy: Comparison of architectures","authors":"Andrew J. Krupien,&nbsp;Yasin Abdulkadir,&nbsp;Dishane C. Luximon,&nbsp;John Charters,&nbsp;Huiming Dong,&nbsp;Jonathan Pham,&nbsp;Dylan O'Connell,&nbsp;Jack Neylon,&nbsp;James M. Lamb","doi":"10.1002/acm2.70089","DOIUrl":"10.1002/acm2.70089","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The use of deep learning-based auto-contouring algorithms in various treatment planning services is increasingly common. There is a notable deficit of commercially or publicly available models trained on large or diverse datasets containing high-dose-rate (HDR) brachytherapy treatment scans, leading to poor performance on images that include HDR implants.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;To implement and evaluate automatic organs-at-risk (OARs) segmentation models for use in prostatic-and-gynecological computed tomography (CT)-guided high-dose-rate brachytherapy treatment planning.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods and materials&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;1316 computed tomography (CT) scans and corresponding segmentation files from 1105 prostatic-or-gynecological HDR patients treated at our institution from 2017 to 2024 were used for model training. Data sources comprised six CT scanners including a mobile CT unit with previously reported susceptibility to image streaking artifacts. Two UNet-derived model architectures, UNet++ and nnU-Net, were investigated for bladder and rectum model training. The models were tested on 100 CT scans and clinically-used segmentation files from 62 prostatic-or-gynecological HDR brachytherapy patients, disjoint from the training set, collected in 2024. Performance was evaluated using the Dice-Similarity-Coefficient (DSC) between model predicted contours and clinically-used contours on slices in common with the Clinical-Target-Volume (CTV). Additionally, a blinded evaluation of ten random test cases was conducted by three experienced planners.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Median (interquartile range) 3D DSC on CTV-containing slices were 0.95 (0.04) and 0.87 (0.09) for the UNet++ bladder and rectum models, respectively, and 0.96 (0.03) and 0.88 (0.10) for the nnU-Net. The rank-sum test did not reveal statistically significant differences in these DSC (&lt;i&gt;p&lt;/i&gt; = 0.15 and 0.27, respectively). The blinded evaluation scored trained models higher than clinically-used contours.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusion&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Both UNet-derived architectures perform similarly on the bladder and rectum and are adequately accurate to reduce contouring time in a review-and-edit context during HDR brachytherapy planning. The UNet++ models were chosen for implementation at our institution due to lower computing hardware requirements and are in routine clinical use.&lt;/p&gt;\u0000 ","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70089","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143788426","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}