Journal of Applied Clinical Medical Physics最新文献

{"title":"Attention 3D UNET for dose distribution prediction of high-dose-rate brachytherapy of cervical cancer: Intracavitary applicators.","authors":"Suman Gautam, Alexander F I Osman, Dylan Richeson, Somayeh Gholami, Binod Manandhar, Sharmin Alam, William Y Song","doi":"10.1002/acm2.14568","DOIUrl":"https://doi.org/10.1002/acm2.14568","url":null,"abstract":"<p><strong>Background: </strong>Formulating a clinically acceptable plan within the time-constrained clinical setting of brachytherapy poses challenges to clinicians. Deep learning based dose prediction methods have shown favorable solutions for enhancing efficiency, but development has primarily been on external beam radiation therapy. Thus, there is a need for translation to brachytherapy.</p><p><strong>Purpose: </strong>This study proposes a dose prediction model utilizing an attention-gating mechanism and a 3D UNET for cervical cancer high-dose-rate intracavitary brachytherapy treatment planning with tandem-and-ovoid/ring applicators.</p><p><strong>Methods: </strong>A multi-institutional data set consisting of 77 retrospective clinical brachytherapy plans was utilized in this study. The data were preprocessed and augmented to increase the number of plans to 252. A 3D UNET architecture with attention gates was constructed and trained for mapping the contour information to dose distribution. The trained model was evaluated on a testing data set using various metrics, including dose statistics and dose-volume indices. We also trained a baseline UNET model for a fair comparison.</p><p><strong>Results: </strong>The attention-gated 3D UNET model exhibited competitive accuracy in predicting dose distributions similar to the ground truth. The average values of the mean absolute errors were 0.46 ± 11.71 Gy (vs. 0.47 ± 9.16 Gy for a baseline UNET) in CTV_HR, 0.55 ± 0.67 Gy (vs. 0.70 ± 1.54 Gy for a baseline UNET) in bladder, 0.42 ± 0.46 Gy (vs. 0.49 ± 1.34 Gy for a baseline UNET) in rectum, and 0.31 ± 0.65 Gy (vs. 0.20 ± 3.76 Gy for a baseline UNET) in sigmoid. Our results showed that the mean individual differences in ΔD_2cc for bladder, rectum, and sigmoid were 0.38 ± 1.19 (p = 0.50), 0.43 ± 0.71 (p = 0.41), and -0.47 ± 0.79 (p = 0.30) Gy, respectively. Similarly, the mean individual differences in ΔD_1cc for bladder, rectum, and sigmoid were 0.09 ± 1.21 (p = 0.36), 0.20 ± 0.95 (p = 0.24), and -0.21 ± 0.59 (p = 0.30) Gy. The mean individual differences for ΔD₉₀, ΔV_100%, ΔV_150%, and ΔV_200% of the CTV_HR were -0.45 ± 2.42 (p = 0.26) Gy, 0.55 ± 9.42% (p = 0.78), 0.82 ± 4.21% (p = 0.81), and -0.80 ± 10.48% (p = 0.36), respectively. The model requires less than 5 s to predict a full 3D dose distribution for a new patient plan.</p><p><strong>Conclusion: </strong>Attention-gated 3D UNET revealed a promising capability in predicting voxel-wise dose distributions compared to 3D UNET. This model could be deployed for clinical use to predict 3D dose distributions for near real-time decision-making before planning, quality assurance, and guiding future automated planning, making the current workflow more efficient.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14568"},"PeriodicalIF":2.0,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142638935","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":"Supported bridge position in one-stop coronary and craniocervical CT angiography: A randomized clinical trial.","authors":"Heng Zhou, Cheng Yan, Min Ji, Zhang Shi, Chun Yang, Mengsu Zeng","doi":"10.1002/acm2.14561","DOIUrl":"https://doi.org/10.1002/acm2.14561","url":null,"abstract":"<p><strong>Objective: </strong>The routine patient arm position differs between coronary CT angiography (CTA) and craniocervical CTA protocols. To investigate the clinical feasibility of supported bridge position (SBP) in combined coronary and craniocervical CTA.</p><p><strong>Methods: </strong>Prospective enrollment included patients with suspected coronary artery disease (CAD) or craniocervical artery disease (CCAD) from February 2022 to November 2022. Patients were divided into three groups: coronary or craniocervical CTA according to CAD or CCAD using standard position (group 1), combined CTA with naturally arm-down position (group 2) and SBP (group 3). Statistical analysis of objective image quality, such as noise and contrast-to-noise ratio (CNR), subjective image quality, patient position and radiation dose was performed among the three groups.</p><p><strong>Results: </strong>Two hundred and one patients (median age, 67 years; 138 men) were included. In terms of CNR for cardiac segment, group 1 and group 3 had no statistical difference, both significantly higher than group 2 (group 1, 12.56 ± 2.05; group 2, 10.4 ± 2.43; group 3, 11.94 ± 2.22; P < 0.05). Subjective image evaluation revealed no statistically significant differences among the three groups of coronary arteries (P > 0.05). Additionally, the lateral project value of scout images at the heart level indicated a significant difference (119.48 ± 12.19, 182.34 ± 25.09, and 140.58 ± 19.68 of patients, for group 1, group 2, and group 3, respectively, P < 0.05). No statistical differences were observed in <math> <semantics><msub><mi>CTDI</mi> <mi>vol</mi></msub> <annotation>${mathrm{CTDI}}_{{mathrm{vol}}}$</annotation></semantics> </math> between group 1 and group 3 (cardiac scan, 15.77 [15.07-16.37] mGy vs. 14.88 [12.19-18.81] mGy; craniocervical scan, 7.85 [7.69-8.01] mGy vs. 7.88 [7.88-7.89] mGy; all P > 0.05). However, group 2 had a higher dose (19.54 [16.86-22.85] mGy and 10.87 [10.86-10.87] mGy, for cardiac and craniocervical scans, respectively).</p><p><strong>Conclusions: </strong>In comparison with a naturally arm-down position, SBP, which aligns the humerus bones with the spinal column, can provide diagnostic image quality at routine dose level of standard position CTA.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14561"},"PeriodicalIF":2.0,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142638970","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":"Deep learning based ultra-low dose fan-beam computed tomography image enhancement algorithm: Feasibility study in image quality for radiotherapy","authors":"Hua Jiang,&nbsp;Songbing Qin,&nbsp;Lecheng Jia,&nbsp;Ziquan Wei,&nbsp;Weiqi Xiong,&nbsp;Wentao Xu,&nbsp;Wei Gong,&nbsp;Wei Zhang,&nbsp;Liqin Yu","doi":"10.1002/acm2.14560","DOIUrl":"10.1002/acm2.14560","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objective</h3>\u0000 \u0000 <p>We investigated the feasibility of deep learning-based ultra-low dose kV-fan-beam computed tomography (kV-FBCT) image enhancement algorithm for clinical application in abdominal and pelvic tumor radiotherapy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A total of 76 patients of abdominal and pelvic tumors were prospectively selected. The Catphan504 was acquired with the same conditions as the standard phantom test set. We used a CycleGAN-based model for image enhancement. Normal dose CT (NDCT), ultra-low dose CT (LDCT) and deep learning enhanced CT (DLR) were evaluated by subjective and objective analyses in terms of imaging quality, HU accuracy, and image signal-to-noise ratio (SNR).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The image noise of DLR was significantly reduced, and the contrast-to-noise ratio (CNR) was significantly improved compared to the LDCT. The most significant improvement was the acrylic which represented soft tissue in CNR from 1.89 to 3.37, improving by 76%, nearly approaching the NDCT, and in low-density resolution from 7.64 to 12.6, improving by 64%. The spatial frequencies of MTF10 and MTF50 in DLR were 4.28 and 2.35 cycles/mm in DLR, respectively, which are higher than LDCT 3.87 and 2.12 cycles/mm, and even slightly higher than NDCT 4.15 and 2.28 cycles/mm. The accuracy and stability of HU values of DLR were similar to NDCT. The image quality evaluation of the two doctors agreed well with DLR and NDCT. A two-by-two comparison between groups showed that the differences in image scores of LDCT compared with NDCT and DLR were all statistically significant (<i>p</i> &lt; 0.05), and the subjective scores of DLR were close to NDCT.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The image quality of DLR was close to NDCT with reduced radiation dose, which can fully meet the needs of conventional image-guided adaptive radiotherapy (ART) and achieve the quality requirements of clinical radiotherapy. The proposed method provided a technical basis for LDCT-guided ART.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11633815/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142620927","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":"Surrogate gating strategies for the Elekta Unity MR-Linac gating system.","authors":"Samuel D Rusu, Blake R Smith, Joel J St-Aubin, Nathan Shaffer, Daniel Ellis Hyer","doi":"10.1002/acm2.14566","DOIUrl":"https://doi.org/10.1002/acm2.14566","url":null,"abstract":"<p><strong>Purpose: </strong>MRI-guided adaptive radiotherapy can directly monitor the anatomical positioning of the intended target during treatment with no additional imaging dose. Elekta has recently released its comprehensive motion management (CMM) solution that enables automatic radiation beam-gating on the Unity MR-Linac. Easily visualized targets that are distinct from the surrounding anatomy can be used to drive automatic gating decisions from the MRI cine imaging. However, poorly visualized targets can compromise the tracking and gating capabilities and may require surrogate tracking structures. This work presents strategies to generate robust tracking surrogates for a variety of treatment sites, enabling a wider application of CMM.</p><p><strong>Methods: </strong>Surrogate tracking strategies were developed from a cohort of patients treated using the CMM system on the Unity MR-Linac for treatment sites of the lung, pancreas, liver, and prostate. These sites posed challenging visualization or tracking of the primary target thereby compromising the tracking accuracy. Surrogate structures were developed using site-specific strategies to improve the imaging textured detail within the tracking volume while avoiding the dynamic overwhelming hypo- or hyper-intense anatomical structures. These surrogate volumes were applied within the anatomical positioning monitoring system as a proxy that drove the CMM gating decisions on the treatment unit.</p><p><strong>Results: </strong>Robust site-specific surrogate structures were developed. Surrogate tracking structures for centrally located thoracic targets were created by expanding the target peripherally away from the heart and great vessels and into the lung. Pancreas surrogates required a vertically expanded column intersecting with the inferior liver edge. For the liver and prostate, surrogate structures consisted of a uniform expansion of the target, with liver surrogates intersecting the proximal liver edge or diaphragm while avoiding nearby ribs.</p><p><strong>Conclusion: </strong>These surrogate strategies have enabled the gating of complex moving targets among different treatment sites at our institution.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14566"},"PeriodicalIF":2.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142620930","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":"<ArticleTitle xmlns:ns0=\"http://www.w3.org/1998/Math/MathML\">Enhancing safety: Multi-institutional FMEA and FTA on <ns0:math> <ns0:semantics> <ns0:mrow><ns0:msup><ns0:mrow /> <ns0:mn>177</ns0:mn></ns0:msup> <ns0:mi>Lu</ns0:mi></ns0:mrow> <ns0:annotation>$^{177}{rm Lu}$</ns0:annotation></ns0:semantics> </ns0:math> -based radio-pharmaceutical therapy.","authors":"Siju C George, Santiago Aguirre, Nichole M Maughan, Ranjini Tolakanahalli, E James Jebaseelan Samuel, Sven L Gallo, Jacqueline E Zoberi, Yongsook C Lee","doi":"10.1002/acm2.14550","DOIUrl":"https://doi.org/10.1002/acm2.14550","url":null,"abstract":"<p><strong>Purpose: </strong>This study investigates potential failure modes and conducts failure mode and effects analysis (FMEA) and fault tree analysis (FTA) on the administration of <math> <semantics> <mrow><msup><mrow></mrow> <mn>177</mn></msup> <mi>Lu</mi></mrow> <annotation>$^{177}{rm Lu}$</annotation></semantics> </math> DOTATATE (LUTATHERA) and <math> <semantics> <mrow><msup><mrow></mrow> <mn>177</mn></msup> <mi>Lu</mi></mrow> <annotation>$^{177}{rm Lu}$</annotation></semantics> </math> PSMA-617 (PLUVICTO). The quality management (QM) process in radiopharmaceutical therapies (RPTs) requires collaboration between nuclear medicine (NM) and radiation oncology (RO) departments. As part of a multi-institutional study, we surveyed various departments to identify and analyze failure modes, leading to a proposed comprehensive QM program. RPT teams in RO or NM clinics can benefit from this study by continually improving their practice.</p><p><strong>Methods: </strong>We reviewed the literature to investigate the administration of Pluvicto and Lutathera, focusing on prospective procedural failures and potential failure modes (PFMs) and their outcomes. We distributed an FMEA survey to multiple experienced centers in <math> <semantics> <mrow><msup><mrow></mrow> <mn>177</mn></msup> <mi>Lu</mi></mrow> <annotation>$^{177}{rm Lu}$</annotation></semantics> </math> -based RPTs and calculated risk priority number (RPN) for various PFM. We conducted an FTA using this information to pinpoint the root causes of potential failures.</p><p><strong>Results: </strong>The findings from the literature review and survey responses on the prospective study have identified several critical areas at risk of failure. These areas include non-optimized treatment delivery, inadequate patient monitoring, and lack of safety training, leading to radiation contamination from the dose excreted by the patients after treatment administration. A segmented FTA was created based on the FMEA results, focusing on radiation contamination with a high RPN value.</p><p><strong>Conclusion: </strong>By identifying the root causes of failures and proposing targeted improvements to the existing QM measures, this analysis enhances safety in treatment delivery of <math> <semantics> <mrow><msup><mrow></mrow> <mn>177</mn></msup> <mi>Lu</mi></mrow> <annotation>$^{177}{rm Lu}$</annotation></semantics> </math> -based RPTs. Given the limited number of prospective risk analysis studies in RPTs, our research addresses the necessity for more such studies and recommends methods to apply this study to other RPTs.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14550"},"PeriodicalIF":2.0,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142620919","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":"Clinical commissioning and introduction of an in-house artificial intelligence (AI) platform for automated head and neck intensity modulated radiation therapy (IMRT) treatment planning.","authors":"Xinyi Li, Yang Sheng, Qingrong Jackie Wu, Yaorong Ge, David M Brizel, Yvonne M Mowery, Dongrong Yang, Fang-Fang Yin, Qiuwen Wu","doi":"10.1002/acm2.14558","DOIUrl":"10.1002/acm2.14558","url":null,"abstract":"<p><strong>Background and purpose: </strong>To describe the clinical commissioning of an in-house artificial intelligence (AI) treatment planning platform for head-and-neck (HN) Intensity Modulated Radiation Therapy (IMRT).</p><p><strong>Materials and methods: </strong>The AI planning platform has three components: (1) a graphical user interface (GUI) is built within the framework of a commercial treatment planning system (TPS). The GUI allows AI models to run remotely on a designated workstation configured with GPU acceleration. (2) A template plan is automatically prepared involving both clinical and AI considerations, which include contour evaluation, isocenter placement, and beam/collimator jaw placement. (3) A well-orchestrated suite of AI models predicts optimal fluence maps, which are imported into TPS for dose calculation followed by an optional automatic fine-tuning. Six AI models provide flexible tradeoffs in parotid sparing and Planning Target Volume (PTV)-organ-at-risk (OAR) preferences. Planners could examine the plan dose distribution and make further modifications as clinically needed. The performance of the AI plans was compared to the corresponding clinical plans.</p><p><strong>Results: </strong>The average plan generation time including manual operations was 10-15  min per case, with each AI model prediction taking ∼1 s. The six AI plans form a wide range of tradeoff choices between left and right parotids and between PTV and OARs compared with corresponding clinical plans, which correctly reflected their tradeoff designs.</p><p><strong>Conclusion: </strong>The in-house AI IMRT treatment planning platform was developed and is available for clinical use at our institution. The process demonstrates outstanding performance and robustness of the AI platform and provides sufficient validation.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14558"},"PeriodicalIF":2.0,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142583191","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 and validation of a questionnaire on radiation protection knowledge, attitudes, and practices among Moroccan dentists.","authors":"Naoual Elmorabit, Majdouline Obtel, Mohamed Azougagh, Asmaa Marrakchi, Oum Keltoum Ennibi","doi":"10.1002/acm2.14555","DOIUrl":"https://doi.org/10.1002/acm2.14555","url":null,"abstract":"<p><strong>Purpose: </strong>This study aimed to develop and evaluate the validity and reliability of dentists' radiation protection knowledge, attitudes, and practices (DRP-KAPs) questionnaire.</p><p><strong>Methods: </strong>This study was conducted using a stepwise approach. In the first step, items were generated to determine the relevant content and domains after a thorough literature review. In the second step, the content validity of the questionnaire was assessed by seven experts using face and content validity. The content validity index for relevance and clarity (I-CVI, S-CVI/Av, and S-CVI/UA) and the content validity ratio (CVR) were performed. Then, the questionnaire was pre-tested with 10 dentists for face validation. In the third step, reliability was assessed using internal consistency (Kuder-Richardson-20 (KR-20) and Cronbach's alpha) and test-retest (Kappa and intraclass correlation coefficient [ICC]) methods by filling out the questionnaire by 100 dentists practicing in the Rabat-Salé-Kénitra region, in Morocco.</p><p><strong>Results: </strong>The finalized DRP-KAPs questionnaire contains 41 items covering knowledge, attitudes and practices (KAPs). The I-CVIs, S-CVI/UA and S-CVI/AV and CVR values of the 41 items were ≥0.86 for each item, ≥0.82, ≥0.97, and ≥0.71, respectively. With regard to internal consistency reliability, the KR-20 coefficients for the knowledge and practice domains were 0.70 and 0.68, respectively, and the Cronbach alpha for the attitude domain was 0.73. The DRP-KAPs questionnaire has good reliability with the ICC coefficients for attitude items ranging from 0.57 to 0.95 and Kappa coefficients for knowledge and practice items ranging from 0.64 to 1 and 0.77 to 1, respectively.</p><p><strong>Conclusion: </strong>The developed DRP-KAPs questionnaire was found to be a noteworthy tool for assessing radiation protection among dentists, with acceptable internal consistency, good ICC and Kappa coefficients, and good content validity indices.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14555"},"PeriodicalIF":2.0,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142583200","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":"Comparative analysis of fetal dose sparing between a C-arm linac and an O-ring linac in a SIB-VMAT sarcoma treatment for a pregnant patient: A technical note and case report.","authors":"Wesley Rivais, Louis Constine, Matthew Pacella, Neil Joyce, Maimuna Nagey, Matthew Webster, Jihyung Yoon, Hyunuk Jung, Sean Tanny, Olga Maria Dona Lemus, Dandan Zheng","doi":"10.1002/acm2.14556","DOIUrl":"https://doi.org/10.1002/acm2.14556","url":null,"abstract":"<p><strong>Purpose: </strong>To compare the effect of two linacs designs on fetal dose sparing on a pregnant patient, including estimation of the fetal dose, and the effect of a lead apron.</p><p><strong>Methods: </strong>A patient with a high-grade sarcoma located in the right knee/lower thigh was prescribed 51 Gy (1.7 Gy/Fx) with a simultaneous-integrated-boost (SIB) of 60 Gy to a smaller volume, starting in the 26th gestational week. Volumetric modulated radiation therapy (VMAT) plans with 6MV-FFF were developed using identical dosimetric constraints on a Varian Truebeam Edge with HD-MLC and a Varian Halcyon with double-stacked MLC. Based on patient dimension measurements, an anthropomorphic phantom was constructed using a Rando phantom and saline bags in the patient's Vac-Lok bag. Phantom measurements were performed using OSLDs and TLDs placed at three different planes, corresponding to the pubis, the umbilicus, and the fundus based on patient measurements and projected gestational age, to estimate the fetal dose. Three experimental scenarios were measured, each with CBCT-based image guidance for an accurate, reproducible setup: Edge, Halcyon, and Halcyon with a tri-folded lead apron (0.5 mm × 3 = 1.5 mm Pb) over the phantom abdomen.</p><p><strong>Results: </strong>Plan quality and total MUs are comparable between the Edge and Halcyon plans. The OSLD-measured whole-course dose to the pubis, umbilicus, and fundus were 18.8, 13.1, and 11.7 cGy, respectively, on Halcyon, on average 27.8% lower than Edge. The repeatability within either dosimeter was good, although TLD showed systematically lower doses. Importantly, both dosimetry systems showed a lower measured fetal dose for the Halcyon plan compared with the Edge plan. Adding a tri-folded lead apron over the abdomen did not meaningfully lower the measured dose.</p><p><strong>Conclusion: </strong>In this case study, Halcyon demonstrated a better sparing of out-of-field fetal dose compared to TrueBeam Edge. It was shown that lead aprons do not provide additional fetal dose sparing.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14556"},"PeriodicalIF":2.0,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574998","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":"Analysis of sagittal plane cine magnetic resonance imaging for measurement of pancreatic tumor residual motion during breath hold and evaluation of gating margins used in radiotherapy treatment.","authors":"Adam Phipps, Maxwell Robinson, Ben George, Tom Whyntie","doi":"10.1002/acm2.14557","DOIUrl":"https://doi.org/10.1002/acm2.14557","url":null,"abstract":"<p><strong>Background and purpose: </strong>In pancreatic radiotherapy, residual tumor motion during treatment increases the risk of toxicity. Cine imaging acquired during magnetic resonance guided radiotherapy (MRgRT) enables real-time treatment gating in response to anatomical motion, which can reduce this risk; however, treatment gating can negatively impact the efficiency of treatment. This study aimed to quantify the extent of residual tumor motion during breath hold and evaluate the appropriateness of the treatment gating margins used in current clinical practice.</p><p><strong>Materials and methods: </strong>Cine imaging acquired during pancreatic MRgRT of 11 patients on the ViewRay MRIdian was analyzed. The total duration of treatment analyzed was 12 h 13 min. Improved methods for processing and analyzing cine imaging were developed: breath holds were systematically separated with frequency analysis, residual motion was measured with consideration of both the tracking structure contour and centroid, and residual motion measurements were supported by phantom measurements of image scaling, resolution, and noise. Residual motion was measured at angles 0°, 45°, 90°, and 135° to the superior-inferior (SI) direction. Total residual motion was measured by combining directional measurements.</p><p><strong>Results: </strong>The minimum tracking structure displacement resolvable through cine imaging was found to be 1.5 mm; therefore, residual motion analysis was limited to 1.5 mm spatial resolution. Total residual motion was contained within margins <math> <semantics><mrow><mi>Δ</mi> <mo>=</mo> <mspace></mspace></mrow> <annotation>$Delta =, $</annotation></semantics> </math> ±1.5, ±3, and ±4.5mm with mean percentage frequencies of 97.0%, 91.1%, and 67.8%. Most residual motion was observed in the SI direction, and significantly more residual motion was measured for the tracking structure contour than the centroid.</p><p><strong>Conclusion: </strong>The results demonstrate that patients are largely able to maintain breath hold positions to within a 3 mm margin, thus provide evidence that supports the use of a 3mm gating margin in clinical practice. Residual motion frequently exceeded 1.5 mm so a reduction in gating margin would have an undesirable impact on treatment efficiency.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14557"},"PeriodicalIF":2.0,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574841","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":"Beyond a constant proton relative biological effectiveness: A survey of clinical and research perspectives among proton institutions in Europe and the United States.","authors":"Jakob Ödén, Kjell Eriksson, Suryakant Kaushik, Erik Traneus","doi":"10.1002/acm2.14535","DOIUrl":"https://doi.org/10.1002/acm2.14535","url":null,"abstract":"<p><strong>Purpose: </strong>Although proton relative biological effectiveness (RBE) depends on factors like linear energy transfer (LET), tissue properties, dose, and biological endpoint, a constant RBE of 1.1 is recommended in clinical practice. This study surveys proton institutions to explore activities using functionalities beyond a constant proton RBE.</p><p><strong>Methods: </strong>Research versions of RayStation integrate functionalities considering variable proton RBE, LET, proton track-ends, and dirty dose. A survey of 19 institutions in Europe and the United States, with these functionalities available, investigated clinical adoption and research prospects using a 25-question online questionnaire.</p><p><strong>Results: </strong>Of the 16 institutions that responded (84% response rate), 13 were clinically active. These clinical institutions prescribe RBE = 1.1 but also employ planning strategies centered around special beam arrangements to address potentially enhanced RBE effects in serially structured organs at risk (OARs). Clinical plan evaluation encompassed beam angles/spot position (69%), dose-averaged LET (LET_d) (46%), and variable RBE distributions (38%). High ratings (discrete scale: 1-5) were reported for the research functionalities using linear LET_d-RBE models, LET_d, track-end frequency and dirty dose (averages: 4.0-4.8), while LQ-based phenomenological RBE models dependent on LET_d scored lower for optimization (average: 2.2) but congruent for evaluation (average: 4.1). The institutions preferred LET reported as LET_d (94%), computed in unit-density water (56%), for all protons (63%), and lean toward LET_d-based phenomenological RBE models for clinical use (> 50%).</p><p><strong>Conclusions: </strong>Proton institutions recognize RBE variability but adhere to a constant RBE while actively mitigating potential enhancements, particularly in serially structured OARs. Research efforts focus on planning techniques that utilize functionalities beyond a constant RBE, emphasizing standardized LET and RBE calculations to facilitate their adoption in clinical practice and improve clinical data collection. LET_d calculated in unit-density water for all protons as input to adaptable phenomenological RBE models was the most suggested approach, aligning with predominant clinical LET and variable RBE reporting.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14535"},"PeriodicalIF":2.0,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142568091","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}