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PurposeTo define optimal planning target volume (PTV) margins for intensity modulated radiotherapy (IMRT) ± knee-heel support (KHS) in patients treated with adjuvant radiotherapy.MethodsComputed tomography (CT) scans ± KHS of 10 patients were taken before and at 3rd and 5th week of treatment, fused and compared with initial IMRT plans.ResultsA PTV margin of 15 mm in anteroposterior (AP) and superoinferior (SI) directions and 5 mm in lateral directions were found to be adequate without any difference between ± KHS except for the SI shifts in CTV-primary at the 3rd week. Five mm margin for iliac CTV was found to be inadequate in 10–20% of patients in SI directions however when 7 mm margin was given for iliac PTV, it was found to be adequate. For presacral CTV, it was found that the most striking shift of the target volume was in the direction of AP. KHS caused significantly less volume of rectum and bladder in the treated volume.ConclusionsPTV margin of 15 mm in SI and AP, and 5 mm in lateral directions for CTV-primary were found to be adequate. A minimum of 7 mm PTV margin should be given to iliac CTV. The remarkable shifting in presacral CTV was believed to be due to the unforeseen hip malposition of obese patients. The KHS seems not to provide additional beneficial effect in decreasing the shifts both in CTV-primary and lymphatic, however it may have a beneficial effect of decreasing the OAR volume in PTV margins.  相似文献   
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A potential effective treatment for prevention of osteoporotic hip fractures is augmentation of the mechanical properties of the femur by injecting it with agents such as (PMMA) bone cement – femoroplasty. The operation, however, is only in research stage and can benefit substantially from computer planning and optimization. We report the results of computational planning and optimization of the procedure for biomechanical evaluation. An evolutionary optimization method was used to optimally place the cement in finite element (FE) models of seven osteoporotic bone specimens. The optimization, with some inter-specimen variations, suggested that areas close to the cortex in the superior and inferior of the neck and supero-lateral aspect of the greater trochanter will benefit from augmentation. We then used a particle-based model for bone cement diffusion simulation to match the optimized pattern, taking into account the limitations of the actual surgery, including limited volume of injection to prevent thermal necrosis. Simulations showed that the yield load can be significantly increased by more than 30%, using only 9 ml of bone cement. This increase is comparable to previous literature reports where gross filling of the bone was employed instead, using more than 40 ml of cement. These findings, along with the differences in the optimized plans between specimens, emphasize the need for subject-specific models for effective planning of femoral augmentation.  相似文献   
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A hierarchical approach to restoration planning at the regional, catchment and local scales is proposed and examined. Restoration projects limited to a local scale and focused on habitat improvement for individual species ended in failure, which has led to the recognition that there is a need for ecosystem-based management at the landscape level. The first landscape-level restoration in Japan is under way in the Kushiro and Shibetsu River Basins, in northern Japan. However, public consensus on these large-scale restoration projects has not yet matured and there are very few projects that have progressed even as far as mapping to classify intact and disturbed ecosystems. Classification of habitat quality using physical and biological indicators appears to be the core element of analysis of ecological degradation at the regional scale (100–1,000 km2). This mass-screening process is critical to identify areas in potential need of restoration. The causes and mechanisms of ecosystem degradation are then examined at the catchment scale (10–100 km2) by linking material flows and habitat conditions. Direct environmental gradient analysis is useful to determine cause and effect relationships between species and habitat quality. Finally, we recommend implementation of field experiments with a clear hypothesis at the local scale (0.01–1 km2). At this stage, key variables causing degradation of the target ecosystem are manipulated to verify the hypothesis. Based on the results of local-scale analyses, the possibility of restoration success can be evaluated, which directs us to practical schemes for future restoration projects at larger scales.  相似文献   
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The Pantanal wetland is a vast seasonally inundated area of extraordinary landscape and biological diversity and complexity. It is located in the upper portion of the Paraguay River basin in central South America. During the rainy season, increased stream discharge from the surrounding basin produces an annual flood pulse through the Pantanal. Increasing human impact, such as dam construction, deforestation, agricultural related activities, and the Hidrovia project in the Parana-Paraguay waterway, threaten the ecological stability of the Pantanal area. As a result, there is an urgent need to introduce new management practices in the Pantanal Basin. In this paper we present a concept for managing the Pantanal catchment based on the integration of ecological knowledge, institutional organization, and involvement of different stakeholders. We propose approaches for an integrated management of the Pantanal and its catchment based on improving data bases and the empowerment of the stakeholder groups. The latter depends on increasing the level of education and access to information, as well as implementing procedures to improve public involvement and enforcement of environmental regulations.This revised version was published online in March 2005 with corrections to the issue cover date.  相似文献   
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在适形放疗中需要在肿瘤体积周围加上三维边缘形成计划靶体积。传统的靶体积到计划体积的扩展方法是在组成靶体积的每层轮廓线外手动勾画一个边缘,费时且结果不准确,本文介绍一种新的三维边缘扩展方法,具有思路简洁,结果准确,节约时间等优点。  相似文献   
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目的分析放疗科设备之间信息的整合。材料与方法通过对DICOM RT(Radiotherapy in DICOM)标准的了解,利用Pinnacle放射治疗计划系统(Treatment Planning System,TPS)、PrecisePLAN放射治疗计划系统和Eclipse放射治疗计划系统对某一选定病人进行轮廓勾画和剂量计算。然后,把轮廓勾画好的病人信息及计算完毕的病人信息分别在这三台TPS之间进行相互传递,并比较传递前后病人信息的差异。结果1)大孔径CT得到的CT图像可以传递给TPS;2)Pinnacle TPS的数据信息可以传递给PrecisePLAN TPS和Eclipse TPS,但是存在轮廓缺陷;3)PrecisePLAN TPS和Eclipse TPs之间不能互相传递数据,也不能把数据信息传递给Pinnacle TPS;4)三台TPS都不能把病人的治疗计划传递给另外的TPS。结论在当前三家国外生产加速器的大公司并存及国内生产加速器的企业落后的情况下,医院设备主管部门应当考虑购买兼容性较好的设备或者购买同一家公司的放射治疗设备。  相似文献   
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Achievement of environmental management goals and objectives in coastal areas, including how to measure success, remains a significant subject for discussion among scholars and practitioners, meanwhile four distinct management efforts potentially converge within the coastal zone: land-use planning (LUP), river basin management (RBM), marine spatial planning (MSP) and integrated coastal management (ICM). This paper examines the general lack of attention being paid to overlapping spatial boundaries within the landward and marine areas and proposes an indicator-based framework to measure the effectiveness of the individual planning instruments, as opposed to specific initiatives, in achieving management goals. The six indicators used in the framework (planning; participation; communication; integration; responsibility and balance) are based on a modified version of the Coastal Sustainability Standard methodology described by Gallagher (2010). The framework provides for four scenarios of progress in three geographical dimensions (river, municipality and marine area) to be assessed. For this study, the Caribbean coast of Colombia and Cuba were identified as the areas to test the feasibility and relevance of the indicator framework to monitor progress in the different management approaches established to achieve coastal sustainability. Several key observations and lessons from the indicator-based framework are discussed in order to analyze the overlapping of the four space-based instruments, identify areas for targeted intervention and improve their integration.  相似文献   
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IntroductionTargeted Radionuclide Therapy (TRT) is a branch of cancer medicine dealing with the therapeutic use of radioisotopes associated with biological vectors accumulating in the tumors/targets, indicated as Molecular Radiotherapy (MRT), or directly injected into the arteries that supply blood to liver tumour vasculature, indicated as Selective RT (SRT). The aim of this work is to offer a panoramic view on the increasing number of commercially-available TRT treatment planning systems (TPSs).Materials and methodsA questionnaire was sent to manufacturers' representatives. Academic software were not considered. Questions were grouped as follows: general information, clinical workflow, calibration procedure, image processing/reconstruction, image registration and segmentation tools, time-activity curve (TAC) fitting and absorbed dose calculation.ResultsAll software reported have CE-marking. TPSs were divided between SRT-dedicated software [4] and MRT [5] dosimetry software. In SRT, since no kinetic process is involved, absorbed dose calculation does not require TAC fitting, and image registration is not fully developed in all TPS. All software requires a radionuclide-specific calibration. In SRT, a relative image calibration can be obtained by scaling the counts to a known activity. Automated VOI contouring and rigid/deformable propagation between different acquisitions time-points is implemented in most TPSs, although DICOM export is rare. Different TAC fits are available depending on the number of time-points. Voxel S-value and Local deposition methods are the most frequent dosimetric approaches; dose-voxel kernel convolution and semi-Monte Carlo method are also available.ConclusionsAvailable TPSs allows performing personalized dosimetry in clinical practice. Individual variations in methodology/algorithms must be considered in the standardisation/harmonization processes.  相似文献   
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PurposeVMAT delivery technique is currently not applicable to Magnetic Resonance-guided radiotherapy (MRgRT) hybrid systems. Aim of this study is to evaluate an innovative VMAT-like (VML) delivery technique.Material and methodsFirst, planning and dosimetric evaluation of the MRgRT VML treatment have been performed on 10 different disease sites and the results have been compared with the corresponding IMRT plans. Then, in the second phase, 10 of the most dosimetrically challenging locally advanced pancreas treatment plans have been retrospectively re-planned using the VML approach to explore the potentiality of this new delivery technique. Finally, VML robustness was evaluated and compared with the IMRT plans, considering a lateral positioning error of ± 5 mm.ResultsIn phase one, all VML plans were within constraint for all OARs. When PTV coverage is considered, in the 50% of the cases VML PTV coverage is equal or higher than in IMRT plan. In the remaining 50%, the highest target under coverage difference in comparison with IMRT plan is −1.71%. The mean and maximum treatment time differences (VML-IMRT) is 0.2 min and 3.1 min respectively. In phase two, the treatment time variation (VML-IMRT), shows a mean, maximum and minimum variations of 1.3, 4.6 and −0.6 min respectively. All VML plans have a better target coverage if compared with IMRT plans, keeping in any case the OARs constraints within tolerance. VML doesn’t increase plan robustness.ConclusionVMAT-like treatment approach appeared to be an efficient planning solution and it was decided to clinically implement it in daily practice, especially in the frame of hypo fractionated treatments.  相似文献   
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