Medical physics最新文献

{"title":"Cover","authors":"","doi":"10.1002/mp.15762","DOIUrl":"https://doi.org/10.1002/mp.15762","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"51 12","pages":"C1"},"PeriodicalIF":3.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.15762","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"List of Advertisers","authors":"","doi":"10.1002/mp.15763","DOIUrl":"https://doi.org/10.1002/mp.15763","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"51 12","pages":"9405"},"PeriodicalIF":3.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.15763","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An automated treatment planning portfolio for whole breast radiotherapy","authors":"Hana Baroudi, Leonard Che Fru, Deborah Schofield, Dominique L. Roniger, Callistus Nguyen, Donald Hancock, Christine Chung, Beth M. Beadle, Kent A. Gifford, Tucker Netherton, Joshua S. Niedzielski, Adam Melancon, Manickam Muruganandham, Meena Khan, Simona F. Shaitelman, Sanjay Shete, Patricia Murina, Daniel Venencia, Sheeba Thengumpallil, Conny Vrieling, Joy Zhang, Melissa P. Mitchell, Laurence E. Court","doi":"10.1002/mp.17588","DOIUrl":"10.1002/mp.17588","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Automation in radiotherapy presents a promising solution to the increasing cancer burden and workforce shortages. However, existing automated methods for breast radiotherapy lack a comprehensive, end-to-end solution that meets varying standards of care.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aims to develop a complete portfolio of automated radiotherapy treatment planning for intact breasts, tailored to individual patient factors, clinical approaches, and available resources.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We developed five automated conventional treatment approaches and utilized an established RapidPlan model for volumetric arc therapy. These approaches include conventional tangents for whole breast treatment, two variants for supraclavicular nodes (SCLV) treatment with/without axillary nodes, and two options for comprehensive regional lymph nodes treatment. The latter consists of wide tangents photon fields with a SCLV field, and a photon tangents field with a matched electron field to treat the internal mammary nodes (IMNs), and a SCLV field. Each approach offers the choice of a single or two isocenter setup (with couch rotation) to accommodate a wide range of patient sizes. All algorithms start by automatically generating contours for breast clinical target volume, regional lymph nodes, and organs at risk using an in-house nnU-net deep learning models. Gantry angles and field shapes are then automatically generated and optimized to ensure target coverage while limiting the dose to nearby organs. The dose is optimized using field weighting for the lymph nodes fields and an automated field-in-field approach for the tangents. These algorithms were integrated into the RayStation treatment planning system and tested for clinical acceptability on 15 internal whole breast patients (150 plans) and 40 external patients from four different institutions in Switzerland, Argentina, Iran, and the USA (360 plans). Evaluation criteria included ensuring adequate coverage of targets and adherence to dose constraints for normal structures. A breast radiation oncologist reviewed the single institution dataset for clinical acceptability (5-point scale) and a physicist evaluated the multi-institutional dataset (use as is or edit).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The dosimetric evaluation across all datasets (510 plans) showed that 100% of the automated plans met the dose coverage requirements for the breast, 99% for the SCLV, 98% for the axillary nodes, and 91% for the IMN. As exp","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1779-1788"},"PeriodicalIF":3.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17588","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction method for ionization chamber dosimetry in flattening filter free radiotherapy based on Monte Carlo simulation","authors":"Guolong Zhang, Ji Huang, Guoxin Wu, Sunjun Jin, Kun Wang, Hao Wu, Hui Zhang, Haizheng Yue, Ruijie Yang, Yujie Wang, Zhipeng Wang, Yaping Qi","doi":"10.1002/mp.17585","DOIUrl":"10.1002/mp.17585","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The clinical use of flattening filter free (FFF) radiotherapy has significantly increased in recent years due to its effective enhancement of dose rates and reduction of scatter dose. A proposal has been made to adjust the incident electron angle of the accelerator to expand the application of FFF beams in areas such as large planning target volumes (PTVs). However, the inherent softening characteristics and non-uniformity of lateral dose distribution in FFF beams inevitably lead to increased dosimetry errors, especially for ionization chambers widely used in clinical practice, which may result in serious accidents during FFF radiotherapy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study constructs a comprehensive Monte Carlo model that encompasses not only conventional FFF beams but also incorporates FFF beams with varying incident electron angles, to investigate dosimetry errors and correction methods in FFF radiotherapy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We have innovatively introduced a FFF output correction factor (<span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>k</mi>\u0000 <mrow>\u0000 <msub>\u0000 <mi>Q</mi>\u0000 <mrow>\u0000 <mi>F</mi>\u0000 <mi>F</mi>\u0000 <mi>F</mi>\u0000 </mrow>\u0000 </msub>\u0000 <mo>,</mo>\u0000 <msub>\u0000 <mi>Q</mi>\u0000 <mrow>\u0000 <mi>W</mi>\u0000 <mi>F</mi>\u0000 <mi>F</mi>\u0000 </mrow>\u0000 </msub>\u0000 </mrow>\u0000 </msub>\u0000 <annotation>${k}_{{Q}_{FFF},{Q}_{WFF}}$</annotation>\u0000 </semantics></math>) to address dosimetry errors in various ionization chambers under different incident electron angle conditions in FFF beams. The primary variations in <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>k</mi>\u0000 <mrow>\u0000 <msub>\u0000 <mi>Q</mi>\u0000 <mrow>\u0000 <mi>F</mi>\u0000 <mi>F</mi>\u0000 <mi>F</mi>\u0000 </mrow>\u0000 </msub>\u0000 <mo>,</mo>\u0000 ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1833-1844"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Model-based CBCT scatter correction with dual-layer flat-panel detector","authors":"Xin Zhang, Jixiong Xie, Yuhang Tan, Ting Su, Jiongtao Zhu, Han Cui, Dongmei Xia, Hairong Zheng, Dong Liang, Yongshuai Ge","doi":"10.1002/mp.17567","DOIUrl":"10.1002/mp.17567","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Recently, the popularity of dual-layer flat-panel detector (DL-FPD) based dual-energy cone-beam CT (CBCT) imaging has been increasing. However, the image quality of dual-energy CBCT remains constrained by the Compton scattered x-ray photons.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>The objective of this study is to develop a novel scatter correction method, named e-Grid, for DL-FPD based CBCT imaging.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>In DL-FPD, a certain portion of the x-ray photons (mainly low-energy [LE] primary and scattered photons) passing through the object are captured by the top detector layer, while the remaining x-ray photons (mainly high-energy [HE] primary and scattered photons) are collected by the bottom detector layer. A linear signal model was approximated between the HE primary and scatter signals and the LE primary and scatter signals. Physical calibration experiments were performed on cone beam and fan beam to validate the aforementioned signal model via linear fittings. Monte Carlo (MC) simulations of a 10 cm diameter water phantom were conducted on GATE at first to verify this newly developed scatter estimation method. In addition, physical validation experiments of water phantom, head phantom, and abdominal phantom were carried out on a DL-FPD based benchtop CBCT imaging system. The image non-uniformity (NU), which represents the relative difference between the center and the edges of CT images, was measured to quantify the reduction of image shading artifacts. Finally, multi-material decomposition was conducted.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The MC results, CBCT images and line profiles, showed that the newly proposed e-Grid approach was able to accurately predict the scatter distributions in both shape and intensity. As a result, uniform CBCT images that are close to the scatter artifact-free reference images can be obtained. Moreover, the physical experiments demonstrated that the e-Grid method can greatly reduce the shading artifacts in both LE and HE CBCT images acquired from DL-FPD. Results also demonstrated that the e-Grid method is effective for varied objects that having different diameters (from 10 to 28 cm). Quantitatively, the NU value was reduced by over 77% in the LE CBCT image and by over 66% in the HE CBCT image on average. As a consequence, the accuracy of the decomposed multi-material bases, iodine and gadolinium, was substantially improved.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The Compton scattered x-ray signals could be sign","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1500-1514"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Virtual imaging trials in medicine: A brief takeaway of the lessons from the first international summit","authors":"Ehsan Samei,&nbsp;Ehsan Abadi,&nbsp;Predrag Bakic,&nbsp;Kristina Bliznakova,&nbsp;Hilde Bosmans,&nbsp;Ann-Katherine Carton,&nbsp;Alejandro F. Frangi,&nbsp;Stephen Glick,&nbsp;Joseph Y. Lo,&nbsp;Paul Kinahan,&nbsp;Andrew Maidment,&nbsp;Francesco Ria,&nbsp;Ioannis Sechopoulos,&nbsp;William Paul Segars,&nbsp;Rie Tanaka,&nbsp;Liesbeth Vancoillie","doi":"10.1002/mp.17587","DOIUrl":"10.1002/mp.17587","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The rapid advancement of medical technologies presents significant challenges for researchers and practitioners. While traditional clinical trials remain the gold standard, they are often limited by high costs, lengthy durations, and ethical constraints. In contrast, in-silico trials and digital twins have emerged not only as efficient and ethical alternatives but also as a complementary technology that can extend beyond classical trials to predict and design new strategies. The successful application of digital twins in industries like nuclear energy, automotive engineering, and aviation underscores their potential in human health.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>In April 2024, Duke University hosted the first international summit on Virtual Imaging Trials in Medicine (VITM). The summit brought together over 130 experts from academia, industry, and regulatory bodies to discuss the latest developments, challenges, and future directions in this field. The event featured plenary speakers, presentations, and panel discussions, emphasizing the integration of clinical and in-silico methods to enhance medical evaluations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Key takeaways included the necessity of diverse and realistic digital patient representations, the integration of physics and biology in simulations, and the development of robust validation frameworks. The summit also highlighted the importance of regulatory science and the establishment of Good Simulation Practices to ensure the credibility and reliability of virtual trials.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The key discussions and insights from the VITM summit underscore the potential of in-silico trials to revolutionize medical research and patient care through personalized, efficient, and ethical evaluation methods. The collaborative efforts and recommendations from this summit aim to drive future advancements in virtual imaging trials in medicine.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1950-1959"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17587","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longitudinal in silico imaging study comparing digital mammography and digital breast tomosynthesis systems","authors":"Miguel A. Lago,&nbsp;Aldo Badano","doi":"10.1002/mp.17571","DOIUrl":"10.1002/mp.17571","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>In silico clinical trials are becoming more sophisticated and allow for realistic assessment and comparisons of medical image system models. These fully computational models enable fast and affordable trial designs that can closely capture trends seen on real clinical trials.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To evaluate three breast imaging system models for digital mammography (DM) and digital breast tomosynthesis (DBT) in a fully-in-silico longitudinal study.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We developed in silico models for three different breast imaging systems by modeling relevant characteristics such as detector technology, pixel size, number of projections, and angular span. We use a computational image reader to detect masses at different growing stages to compute the relative system performance. Similarly, we compare calcification cluster detectability across systems. The Detectability area under the ROC curve (AUC) was calculated for each combination of breast density, device model, lesion size and type, and search area. We compared the absolute and relative AUC values for DM and DBT. The trial consisted of 45 000 simulated images corresponding to 750 virtual digital patient models.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We observed proportional AUC values with increasing mass size. On the other hand, higher breast densities showed lower AUC values. For masses, we found significant performance differences between device models. The highest average AUC difference between DBT and DM was 0.109, benefiting DBT. For calcifications, DM showed higher performance than DBT, especially in highly dense breasts. The highest AUC difference on a model was –0.055, benefiting DM.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>In this fully-in-silico imaging trial, we compared three imaging systems with different detector technologies on the same cohort of virtual digital patient models. We found that breast device systems can lead to visibility differences in masses and calcifications. Our longitudinal, multi-device in silico study was possible because of the versatility and flexibility of in silico methods. This study shows the advantages of this in silico methodology in lowering the resources needed for device development, optimization, and regulatory evaluation.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1960-1968"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and 3D printing of pelvis phantoms for cementoplasty","authors":"Cléa Sieffert,&nbsp;Laurence Meylheuc,&nbsp;Bernard Bayle,&nbsp;Julien Garnon","doi":"10.1002/mp.17560","DOIUrl":"10.1002/mp.17560","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;Percutaneous image-guided cementoplasty is a medical procedure for strengthening bones structurally altered by disease, such as osteolytic metastasis. This procedure involves injecting biocompatible liquid bone cement, through one or more trocars into the damaged bone. Within a few minutes the bone cement hardens and restores the rigidity of the bony structure. The introduction of this technique in the case of large cancellous bones, such as the pelvis, raises some practical issues such as: how to manage the flow of cement with variable viscosity over time and how to inject a large amount of cement under fluoroscopy to effectively restore the patient's ability to bear weight?&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;As a means of training for young practitioners to ensure maximal filling of a metastatic bone area, we have designed and manufactured a pelvic phantom capable of replicating cement diffusion in healthy and metastatic bone under fluoroscopic and computed tomography guidance.&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;The preliminary stage of the study consisted of an analysis of various lattice structures, with the objective of reproducing the haptic feedback experienced during the needle insertion and diffusion of cement within the trabecular bone. Cementoplasty tests were conducted by an experienced radiologist under fluoroscopy and CT guidance to evaluate the performance of the lattice structure. The initial analysis provided the groundwork for the design of the phantom pelvis, which was then evaluated against a patient case. The phantom was divided into two distinct components: a disposable section with lattice structure, intended for the injection of cement, and a reusable part representing the pelvic bones. Two additive manufacturing methods were selected for the production of the phantom: Stereolithography (SLA) for the lattice structure and Fused Deposition Modeling (FDM) for the pelvic bones. The disposable component was composed of different lattice structures, selected to best match the anatomic conditions of both healthy and diseased areas visible on the patient images. Subsequently, the performance of the phantom was validated against patient images through a cementoplasty test.&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;A total of 12 distinct lattice structures were subjected to three tests of cementoplasty. Stochastic lattices with 500 microns beam thickness and densities varying from 15% to 5% demonstrated the most effective replication of the needle haptic feedback, as w","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1454-1467"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17560","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A 2D detector array for relative dosimetry and beam steering for FLASH radiotherapy with electrons","authors":"Andreas A. Schönfeld,&nbsp;Jeff Hildreth,&nbsp;Alexandra Bourgouin,&nbsp;Veronika Flatten,&nbsp;Jakub Kozelka,&nbsp;William Simon,&nbsp;Andreas Schüller","doi":"10.1002/mp.17573","DOIUrl":"10.1002/mp.17573","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;FLASH radiotherapy is an emerging treatment modality using ultra-high dose rate beams. Much effort has been made to develop suitable dosimeters for reference dosimetry, yet the spatial beam characteristics must also be characterized to enable computerized treatment planning, as well as quality control and service of a treatment delivery device. In conventional radiation therapy, this is commonly achieved by beam profile scans in a water phantom using a point detector. In ultra-high dose rate beams, the delivered dose needed for a set of beam profile scans may exceed the regulatory dose limit specified for a typical treatment room, or degrade components of the scanning system and scanning detector. Point detector scans also cannot quantify the pulse-to-pulse stability of a beam profile. Detector arrays can overcome these challenges, but to date, no detector arrays suitable for ultra-high dose rate beams are commercially available.&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;The study presents the development and characterization of a two-dimensional detector array for measuring pulse-resolved spatial fluence distributions in real-time and temporal structure of intra-pulse dose rate of ultra-high pulsed dose rate (UHPDR) electron beams used in FLASH radiotherapy.&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;The performance of the SunPoint 1 diode was evaluated by measuring the response of the EDGE Detector in a 20 MeV UHPDR electron beam with a dose per pulse of 0.04 Gy – 6 Gy at a pulse duration of 1 µs or 1.9 µs, and instantaneous dose rates of 0.040 – 3.2 MGy·s&lt;sup&gt;−1&lt;/sup&gt;. Based on the findings regarding a suitable signal acquisition technique, a PROFILER 2 detector array made of SunPoint 1 diodes was then modified by minimizing trace resistance, applying a reverse bias, and implementing an RC component to each diode to optimize the transfer of the collected charge during a pulse. The resultant “FLASH Profiler” was then tested in the same UHPDR electron beam.&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 FLASH Profiler exhibited a linear response within ± 3% deviation over the investigated dose per pulse range. The FLASH Profiler array showed good agreement with the absolute dose measured using a flashDiamond point detector and an integrating current transformer for dose-per-pulse values of up to 6 Gy. The FLASH Profiler was able to measure lateral beam profiles in real-time and on a single-pulse basis. The ability to capture and display the profiles during steering of UHPDR beams was demonstrated. ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1845-1857"},"PeriodicalIF":3.2,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17573","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dosimetric study of synchrotron rapid beam off control and skip spot function for high beam intensity proton therapy","authors":"Masashi Yagi,&nbsp;Keith M. Furutani,&nbsp;Toshiyuki Ogata,&nbsp;Takuya Nomura,&nbsp;Masumi Umezawa,&nbsp;Xiaoying Liang,&nbsp;Kei Yamada,&nbsp;Hideya Yamazaki,&nbsp;Shinichi Shimizu,&nbsp;Chris J. Beltran","doi":"10.1002/mp.17589","DOIUrl":"10.1002/mp.17589","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;All Hitachi proton pencil beam scanning facilities currently use discrete spot scanning (DSS). Mayo Clinic Florida (MCF) is installing a Hitachi particle therapy system with advanced technologies, including fast scan speeds, high beam intensity, rapid beam off control (RBOC), a skip spot function, and proton pencil beam scanning using dose driven continuous scanning (DDCS). A potential concern of RBOC is the generation of a shoulder at the end of the normal spot delivery due to a flap spot (FS) with a flap dose (FD), which has been investigated for carbon synchrotron but not for proton delivery. While investigated, for instance, for Hitachi's installation at MCF, this methodology could be applicable for all future high intensity proton deliveries.&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;No Hitachi proton facility currently uses the proposed RBOC. This study aimed to understand the dosimetric impact of proton FD at MCF by simulating the FS with a Hitachi proton machine in research mode, reflecting the higher proton intensities expected with RBOC at MCF.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Method&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Experiments were conducted to simulate MCF RBOC at Kyoto Prefecture University of Medicine (KPUM) in research mode, reducing delay time (Td) from 1.5 ms to 0.1 ms. 5,000 contiguous spots were delivered on the central axis for proton energies of 70.2, 142.5, and 220.0 MeV; at normal, high dose rate (HDR), and ultra-high dose rate (uHDR) intensities; and at vertical and horizontal gantry angles for different Td. Measurements were taken using a fast oscilloscope and the nozzle's spot position monitor (SPM) and dose monitor (DM). A model was developed to predict FD dependence on beam intensity and assess the dosimetric impact for prostate and brain treatment plans. Two simulation types were planned: a flap DSS plan with FS at every spot and a flap DDCS plan with FS only at the end of each layer.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Result&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;FD was observed for RBOC with Td = 0.1 ms, showing no gantry angle dependence. FD increased with higher delayed dose rate (DDR), that is, beam intensity. The planning study showed dose volume histogram deterioration with increased FD compared to the clinical plan, but it was only significant for uHDR intensities. Deterioration was marginal in flap DSS plans for the HDR intensities planned at MCF, and flap DDCS plans were even less sensitive than flap DSS plans.&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;MCF is installing proton DDCS with higher beam intensities, a skip spot fu","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 3","pages":"1867-1877"},"PeriodicalIF":3.2,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}