4,846 research outputs found
Health-Related Quality of Life in Patients with CVID Under Different Schedules of Immunoglobulin Administration: Prospective Multicenter Study
We assessed the health-related quality of life (HRQoL) in CVID adults receiving different schedules of immunoglobulin replacement therapy (IgRT) by intravenous (IVIG), subcutaneous (SCIG), and facilitated (fSCIG) preparations. For these patients, IgRT schedule was chosen after a period focused on identifying the most suitable individual option
Quasiperiodic tilings under magnetic field
We study the electronic properties of a two-dimensional quasiperiodic tiling,
the isometric generalized Rauzy tiling, embedded in a magnetic field. Its
energy spectrum is computed in a tight-binding approach by means of the
recursion method. Then, we study the quantum dynamics of wave packets and
discuss the influence of the magnetic field on the diffusion and spectral
exponents. Finally, we consider a quasiperiodic superconducting wire network
with the same geometry and we determine the critical temperature as a function
of the magnetic field.Comment: 6 pages, 5 EPS figure
Feasibility of intensity-modulated and image-guided radiotherapy for functional organ preservation in locally advanced laryngeal cancer
Purpose: The study aims to assess the feasibility of intensity-modulated and image-guided radiotherapy (IMRT, and IGRT, respectively) for functional preservation in locally advanced laryngeal cancer. A retrospective review of 27 patients undergoing concurrent chemoradiation for locally advanced laryngeal cancers (8 IMRT, 19 IGRT) was undertaken. In addition to regular clinical examinations, all patients had PET imaging at 4 months and 10 months after radiotherapy, then yearly. Loco-regional control, speech quality and feeding-tube dependency were assessed during follow-up visits. Results: At a median follow-up of 20 months (range 6-57 months), four out of 27 patients (14.8%) developed local recurrence and underwent salvage total laryngectomy. One patient developed distant metastases following salvage surgery. Among the 23 patients who conserved their larynx with no sign of recurrence at last follow-up, 22 (95%) reported normal or near normal voice quality, allowing them to communicate adequately. Four patients (14.8%) had long-term tube feeding-dependency because of severe dysphagia (2 patients) and chronic aspiration (2 patients, with ensuing death from aspiration pneumonia in one patient). Conclusions and Clinical Relevance: Functional laryngeal preservation is feasible with IMRT and IGRT for locally advanced laryngeal cancer. However, dysphagia and aspiration remain serious complications, due most likely to high radiation dose delivery to the pharyngeal musculatures. © 2012 Nguyen et al
Optimization of treatment planning workflow and tumor coverage during daily adaptive magnetic resonance image guided radiation therapy (MR-IGRT) of pancreatic cancer
Abstract Background To simplify the adaptive treatment planning workflow while achieving the optimal tumor-dose coverage in pancreatic cancer patients undergoing daily adaptive magnetic resonance image guided radiation therapy (MR-IGRT). Methods In daily adaptive MR-IGRT, the plan objective function constructed during simulation is used for plan re-optimization throughout the course of treatment. In this study, we have constructed the initial objective functions using two methods for 16 pancreatic cancer patients treated with the ViewRayâą MR-IGRT system: 1) the conventional method that handles the stomach, duodenum, small bowel, and large bowel as separate organs at risk (OARs) and 2) the OAR grouping method. Using OAR grouping, a combined OAR structure that encompasses the portions of these four primary OARs within 3 cm of the planning target volume (PTV) is created. OAR grouping simulation plans were optimized such that the target coverage was comparable to the clinical simulation plan constructed in the conventional manner. In both cases, the initial objective function was then applied to each successive treatment fraction and the plan was re-optimized based on the patientâs daily anatomy. OAR grouping plans were compared to conventional plans at each fraction in terms of coverage of the PTV and the optimized PTV (PTV OPT), which is the result of the subtraction of overlapping OAR volumes with an additional margin from the PTV. Results Plan performance was enhanced across a majority of fractions using OAR grouping. The percentage of the volume of the PTV covered by 95% of the prescribed dose (D95) was improved by an average of 3.87â±â4.29% while D95 coverage of the PTV OPT increased by 3.98â±â4.97%. Finally, D100 coverage of the PTV demonstrated an average increase of 6.47â±â7.16% and a maximum improvement of 20.19%. Conclusions In this study, our proposed OAR grouping plans generally outperformed conventional plans, especially when the conventional simulation plan favored or disregarded an OAR through the assignment of distinct weighting parameters relative to the other critical structures. OAR grouping simplifies the MR-IGRT adaptive treatment planning workflow at simulation while demonstrating improved coverage compared to delivered pancreatic cancer treatment plans in daily adaptive radiation therapy
Use of IV contrast media in pre-treatment radiotherapy planning CT scans: A UK study (Abstract only)
Technical Note: Enhancing Soft Tissue Contrast And RadiationâInduced Image Changes With DualâEnergy CT For Radiation Therapy
Purpose
The purpose of this work is to investigate the use of lowâenergy monoenergetic decompositions obtained from dualâenergy CT (DECT) to enhance image contrast and the detection of radiationâinduced changes of CT textures in pancreatic cancer. Methods
The DECT data acquired for 10 consecutive pancreatic cancer patients during routine nongated CTâguided radiation therapy (RT) using an inâroom CT (Definition AS Open, Siemens Healthcare, Malvern, PA) were analyzed. With a sequential DE protocol, the scanner rapidly performs two helical acquisitions, the first at a tube voltage of 80 kVp and the second at a tube voltage of 140 kVp. Virtual monoenergetic images across a range of energies from 40 to 140 keV were reconstructed using an imageâbased material decomposition. Intravenous (IV) bolusâfree contrast enhancement in pancreas patient tumors was measured across a spectrum of monoenergies. For treatment response assessment, the changes in CT histogram features (including mean CT number (MCTN), entropy, kurtosis) in pancreas tumors were measured during treatment. The results from the monoenergetic decompositions were compared to those obtained from the standard 120 kVp CT protocol for the same subjects. Results
Data of monoenergetic decompositions of the 10 patients confirmed the expected enhancement of soft tissue contrast as the energy is decreased. The changes in the selected CT histogram features in the pancreas during RT delivery were amplified with the lowâenergy monoenergetic decompositions, as compared to the changes measured from the 120 kVp CTs. For the patients studied, the average reduction in the MCTN in pancreas from the first to the last (the 28th) treatment fraction was 4.09 HU for the standard 120 kVp and 11.15 HU for the 40 keV monoenergetic decomposition. Conclusions
Lowâenergy monoenergetic decompositions from DECT substantially increase soft tissue contrast and increase the magnitude of radiationâinduced changes in CT histogram textures during RT delivery for pancreatic cancer. Therefore, quantitative DECT may assist the detection of early RT response
A multiregion general equilibrium analysis of fiscal consolidation in South Africa:
A multiregion applied general equilibrium model is used to examine the financial interactions among spheres of government in the context of fiscal consolidation. The framework combines nine regional submodels interacting through the trading of goods and services and the mobility of labor and capital. The model integrates intergovernmental fiscal transfers, which play an important role in reducing the disparity in living standards between regions. The analysis demonstrates that the current intergovernmental revenue transfer system has significant inter- and intraregional equity effects, although its nationwide impact is less important. Reducing intergovernmental transfers leads to a reduction in welfare in the four regions where the net transfers were initially positive (Limpopo, Eastern Cape, KwaZulu-Natal, and North West Province). In contrast, welfare increases in the five other regions (Northern Cape, Mpumalanga, Free State, Gauteng, and the Western Cape). When transfer revenues fall and, consequently, regional and local government revenues drop, poor households are the most affected, as they depend more on public services that are essentially financed by governments. When the government's fiscal position improves, it is also poor households that benefit more from additional government expenses.intergovernmental transfer, multiregion applied general equilibrium, consolidation, welfare,
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