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排序方式: 共有298条查询结果,搜索用时 15 毫秒
1.
Background: A new VMAT method called “Augmented Arc” (or simply Aug Arc) is proposed. The aim of this study is to demonstrate the validity of the proposed method in different clinical cases. Basically, Aug Arc refers to the portion(s) of the VMAT arc that is augmented with an additional arc to improve the plan quality. The Aug Arc portions in the Arc is determined using an objective function-based scoring method called “ψ – score”. Methods: To validate our approach, we have applied it in four clinical cases: Lung, Abdomen, Gynecologic (Gyn) and Pancreas. Basically, for Lung and Pancreas cases, four sets of plans were created, which are: (1) Single arc plan (S Arc), (2) Double arc plan (D Arc), (3) Partial Arc plan without Aug Arc (P Arc) and (4) Partial plan with Aug Arc (P+Aug Arc). For Abdomen and Gyn cases, three sets of plans were created, which are: (1) Single arc plan (S Arc), (2) Double arc plan (D Arc) and (3) Single Arc with Aug Arc (S+Aug Arc). To compute the “ψ – score”, an initial optimization was performed by using full Arc with 4-degree gantry spacing. Subsequently, Aug Arc portions were identified using the ψ – score plot in the single arc and partial arc scenarios. Results: The study finds that the proposed method is useful to improve the plan quality and plan deliverability for both centrically and non-centrically located tumors in terms of reducing the OAR dose, monitor units, beam on time and low dose volume without compromising the target coverage. Conclusion: The results indicate that the proposed approach could strike a balance between full double arc and single arc or partial arc in such a way that the planner can find a sweet spot of delivery parameters that result in optimal plan quality. 相似文献
3.
Marguerite Tyran Hugues Mailleux Agnes Tallet Pierre Fau Laurence Gonzague Mathieu Minsat Laurence Moureau-Zabotto Michel Resbeut 《Journal of radiation research》2015,56(6):927-937
We compared two intensity-modulated radiotherapy techniques for left-sided breast treatment, involving lymph node irradiation including the internal mammary chain. Inverse planned arc-therapy (VMAT) was compared with a forward-planned multi-segment technique with a mono-isocenter (MONOISO). Ten files were planned per technique, delivering a 50-Gy dose to the breast and 46.95 Gy to nodes, within 25 fractions. Comparative endpoints were planning target volume (PTV) coverage, dose to surrounding structures, and treatment delivery time. PTV coverage, homogeneity and conformality were better for two arc VMAT plans; V95%PTV-T was 96% for VMAT vs 89.2% for MONOISO. Homogeneity index (HI)PTV-T was 0.1 and HIPTV-N was 0.1 for VMAT vs 0.6 and 0.5 for MONOISO. Treatment delivery time was reduced by a factor of two using VMAT relative to MONOISO (84 s vs 180 s). High doses to organs at risk were reduced (V30left lung = 14% using VMAT vs 24.4% with MONOISO; dose to 2% of the volume (D2%)heart = 26.1 Gy vs 32 Gy), especially to the left coronary artery (LCA) (D2%LCA = 34.4 Gy vs 40.3 Gy). However, VMAT delivered low doses to a larger volume, including contralateral organs (mean dose [Dmean]right lung = 4 Gy and Dmeanright breast = 3.2 Gy). These were better protected using MONOISO plans (Dmeanright lung = 0.8 Gy and Dmeanright breast = 0.4 Gy). VMAT improved PTV coverage and dose homogeneity, but clinical benefits remain unclear. Decreased dose exposure to the LCA may be clinically relevant. VMAT could be used for complex treatments that are difficult with conventional techniques. Patient age should be considered because of uncertainties concerning secondary malignancies. 相似文献
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The purpose of this study was to design a toolkit that interacts with the Monaco (Elekta AB, Stockholm, Sweden) treatment planning system (TPS) for optimization of intensity-modulated radiation therapy and volumetric-modulated arc therapy without the need for a dedicated application programming interface. Successful inverse planning of radiotherapeutic treatment depends on the tweaking of many parameters; a tool was thus needed to explore these parameters more exhaustively without significantly increasing planning time. The software that we used was based on an open-source library that mimics human interaction with Microsoft Windows applications. We developed a simple Autoflow software routine that analyzes and optimizes calculated plans by considering the relative impact of different cost functions and modifying constraints accordingly. It was also designed to change segmentation parameters to fit more complex treatments. The toolkit is publicly available for download at https://bitbucket.org/hgugmradiofisica/pymonaco/src/master/. A study of prostate cancer cases was conducted to compare automatically created plans with previously treated cases. The toolkit fully automated the radiotherapy planning procedure, allowing the TPS to calculate or optimize plans during nonworking hours. In the prostate study, the use of this tool reduced the dose to organs at risk with a negligible decrease in target coverage. This tool enables the efficient use of the TPS, allowing research and clinical applications to coexist without conflict. It provides consistency and efficiency throughout the treatment planning process, which may be of great value to clinics with few resources. The impact of this tool on clinical workflow is important, as it not only provides better efficiency, but also increases treatment quality. 相似文献
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《Journal of Medical Imaging and Radiation Sciences》2020,51(1):103-107
BackgroundTraditionally, rectal cancer radiation therapy uses bony landmark fields to cover common lymphatic drainage sites, including the internal iliac, presacral, and perirectal lymph nodes. We aimed to investigate if bony landmark borders sufficiently cover the internal iliac nodes and to compare tumor volume and normal tissue avoidance using classic bony landmarks (c3DCRT), contoured elective clinical target volume (f3DCRT), and volumetric modulated arc therapy (VMAT) planning in locally advanced rectal cancer.MethodsComputed tomography datasets of 11 patients with locally advanced rectal cancer who had completed treatment in the prone position on a bellyboard in c3DCRT technique. The elective clinical target volumes and organs at risk were contoured, and a f3DCRT VMAT plan generated for all patients. Planning target volume, gross tumor volume, and normal tissue dose limits were evaluated.ResultsThe mean planning target volume 95% coverages were significantly lower for c3DCRT plans, and the lymph node coverage was better for f3DCRT. No differences were found in PTV coverages between f3DCRT and volumetric modulated arc therapy plans. No significant differences among all techniques were found for organs-at-risk constraints. The bladder dosage was higher in the VMAT plan. The c3DCRT technique missed coverage of the internal iliac lymph nodes and exposed smaller bowel, compared with the other methods.Discussion and ConclusionTumor volume coverage was improved by f3DCRT planning, without significant differences in doses to critical structures compared with c3DCRT and was noninferior to VMAT planning. It is recommended that f3DCRT be used in routine clinical practice in radiotherapy treatments for locally advanced rectal cancer. 相似文献
8.
Hongying Han Xiaowei Xia Huirong Zheng Chongbang Zhao Yanming Xu Jiong Tao Xianglan Wang 《Psychiatry investigation》2020,17(11):1073
ObjectiveTo investigate the association between gene polymorphism of vesicular monoamine transporter type 2(VMAT2) and schizophrenia in Han Chinese population. Methods430 patients with schizophrenia and 470 age-sex matched controls were recruited from four mental health centers. All patients were diagnosed by two psychiatrists based on the Structured Clinical Interview for DSM Disorders (SCID). The ligase detection reactions (LDR) method was used to assess the polymorphism of the two SNPs (rs363371 and rs363324) of VMAT2. ResultsNo associations of two SNPs with schizophrenia was found. When we stratified males and females for the analysis, we found that that in the recessive model of rs363371, there was an obvious significant association between rs363371 and schizophrenia in males (OR=0.564, 95% CI=0.357–0.892, p=0.014) but not females. For the association between rs363324 and schizophrenia, no association was found in either males or females. No association was found when stratifying early-onset schizophrenia and late-onset schizophrenia. ConclusionOur findings indicate that both rs363371 and rs363324 were not associated with schizophrenia, while it seemed that the AA genotype of rs363371 plays a protective effect in male Chinese in developing schizophrenia. 相似文献
9.
Emily Behling MD Candidate Luis C. Farhat MD Angeli Landeros-Weisenberger MD Michael H. Bloch MD MS 《Movement disorders》2022,37(4):684-693
Vesicular monoamine transporter type 2 (VMAT2) inhibitors may be an effective therapy for chronic tic disorders (CTD), including Tourette syndrome (TS), but there has not been a meta-analysis compiling available evidence from randomized controlled trials (RCTs). We performed a systematic review and meta-analysis to evaluate the efficacy, acceptability, and tolerability of VMAT2 inhibitors for CTD/TS. PubMed, CENTRAL, and Embase were searched for double-blinded RCTs of VMAT2 inhibitors versus placebo for the treatment of CTD/TS. Change in tic severity measured by the Yale Global Tic Severity Scale (efficacy) and rates of discontinuation attributed to adverse effects (tolerability) or all causes (acceptability) were extracted closest to 12 weeks. Mean difference (MD) and odds ratio (OR) were the effect size indexes for efficacy and acceptability/tolerability, respectively. Data were pooled through random-effects meta-analysis weighted by inverse variance. Five RCTs involving eight comparisons were included. Meta-analysis found a nonsignificant effect on efficacy (k = 8; N = 583; MD = −0.71; 95% confidence interval [CI], −1.93 to 0.50; P = 0.24), and there was certainty that the true effect is nonclinically meaningful (high quality of evidence). Meta-analysis found decreased tolerability (k = 7; N = 626; OR = 2.67; 95% CI, 1.21–5.92; P = 0.01) and decreased acceptability (k = 8; N = 626; OR = 1.90; 95% CI, 1.14–3.18; P = 0.01), although those comparisons were limited because of the relatively small number of events across trials. Meta-analyses did not support the efficacy of VMAT2 inhibitors in the short-term treatment of tic disorders and suggested no clinically meaningful effect of these agents on tic symptoms. © 2022 International Parkinson and Movement Disorder Society 相似文献
10.
NBI‐98854, a selective monoamine transport inhibitor for the treatment of tardive dyskinesia: A randomized,double‐blind,placebo‐controlled study 下载免费PDF全文