950 resultados para Radiotherapy Setup Errors
Resumo:
BACKGROUND: Stage IIIB non-small-cell lung cancer (NSCLC) is usually thought to be unresectable, and is managed with chemotherapy with or without radiotherapy. However, selected patients might benefit from surgical resection after neoadjuvant chemotherapy and radiotherapy. The aim of this multicentre, phase II trial was to assess the efficacy and toxicity of a neoadjuvant chemotherapy and radiotherapy followed by surgery in patients with technically operable stage IIIB NSCLC. METHODS: Between September, 2001, and May, 2006, patients with pathologically proven and technically resectable stage IIIB NSCLC were sequentially treated with three cycles of neoadjuvant chemotherapy (cisplatin with docetaxel), immediately followed by accelerated concomitant boost radiotherapy (44 Gy in 22 fractions) and definitive surgery. The primary endpoint was event-free survival at 12 months. Efficacy analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00030810. FINDINGS: 46 patients were enrolled, with a median age of 60 years (range 28-70). 13 (28%) patients had N3 disease, 36 (78%) had T4 disease. All patients received chemotherapy; 35 (76%) patients received radiotherapy. The main toxicities during chemotherapy were neutropenia (25 patients [54%] at grade 3 or 4) and febrile neutropenia (nine [20%]); the main toxicity after radiotherapy was oesophagitis (ten patients [29%]; nine grade 2, one grade 3). 35 patients (76%) underwent surgery, with pneumonectomy in 17 patients. A complete (R0) resection was achieved in 27 patients. Peri-operative complications occurred in 14 patients, including two deaths (30-day mortality 5.7%). Seven patients required a second surgical intervention. Pathological mediastinal downstaging was seen in 11 of the 28 patients who had lymph-node involvement at enrolment, a complete pathological response was seen in six patients. Event-free survival at 12 months was 54% (95% CI 39-67). After a median follow-up of 58 months, the median overall survival was 29 months (95% CI 16.1-NA), with survival at 1, 3, and 5 years of 67% (95% CI 52-79), 47% (32-61), and 40% (24-55). INTERPRETATION: A treatment strategy of neoadjuvant chemotherapy and radiotherapy followed by surgery is feasible in selected patients. Toxicity is considerable, but manageable. Survival compares favourably with historical results of combined treatment for less advanced stage IIIA disease. FUNDING: Swiss Group for Clinical Cancer Research (SAKK) and an unrestricted educational grant by Sanofi-Aventis (Switzerland).
Resumo:
We aimed to examine different intratumoral changes after single-dose and fractionated radiotherapy, using diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI in a rat rhabdomyosarcoma model. Four WAG/Rij rats with rhabdomyosarcomas in the flanks received single-dose radiotherapy of 8 Gy, and four others underwent fractionated radiotherapy (five times 3 Gy). In rats receiving single-dose radiotherapy, a significant perfusion decrease was found in the first 2 days post-treatment, with slow recuperation afterwards. No substantial diffusion changes could be seen; tumor growth delay was 12 days. The rats undergoing fractionated radiotherapy showed a similar perfusion decrease early after the treatment. However, a very strong increase in apparent diffusion coefficient occurred in the first 10 days; growth delay was 18 days. DW-MRI and DCE-MRI can be used to show early tumoral changes induced by radiotherapy. Single-dose and fractionated radiotherapy induce an immediate perfusion effect, while the latter induces more intratumoral necrosis.
Resumo:
This paper reviews research findings on entrepreneurial top management teams within the last 20 years. It concentrates on team-based management factors and their influence on a new venture’s growth and ability to raise capital. This paper integrates recent findings and provides an overview of the current state of research. Moreover, it contributes to the overall topic by proposing five clusters of major team-specific influences, derives determinants of success and failure, and reveals recommendations for further research.
Resumo:
Fahrerlose Transportsysteme (FTS) kommen in der Intralogistik immer mehr zum Einsatz. Dabei wer-den neue Anforderungen an die FTS gestellt, die bisherige Aufgaben weit übersteigen. Der Transport von schweren Lasten und die Fahrt mehrere FTS in einer Formation sind dabei nur der Anfang einer Menge zukünftiger Einsatzgebiete. Große Probleme stellen dabei Schlupf und Verschleiß dar, die bisher noch kaum erforscht sind, welche die Performance der Fahrzeuge jedoch stark beeinträchtigen. Um diese Fehlerquellen besser verstehen zu können, wurde ein Versuchsstand entwickelt, mit dessen Hilfe Einzelfahrten aber auch Formationsfahrten in Bezug auf Schlupf und Verschleiß besser untersucht werden können. Dabei kann ein sehr breites Spektrum an Fahrzeugarten abgedeckt werden, da Parameter wie Lenksysteme oder Bereifung variabel gewählt werden können.
Resumo:
We introduce an algorithm (called REDFITmc2) for spectrum estimation in the presence of timescale errors. It is based on the Lomb-Scargle periodogram for unevenly spaced time series, in combination with the Welch's Overlapped Segment Averaging procedure, bootstrap bias correction and persistence estimation. The timescale errors are modelled parametrically and included in the simulations for determining (1) the upper levels of the spectrum of the red-noise AR(1) alternative and (2) the uncertainty of the frequency of a spectral peak. Application of REDFITmc2 to ice core and stalagmite records of palaeoclimate allowed a more realistic evaluation of spectral peaks than when ignoring this source of uncertainty. The results support qualitatively the intuition that stronger effects on the spectrum estimate (decreased detectability and increased frequency uncertainty) occur for higher frequencies. The surplus information brought by algorithm REDFITmc2 is that those effects are quantified. Regarding timescale construction, not only the fixpoints, dating errors and the functional form of the age-depth model play a role. Also the joint distribution of all time points (serial correlation, stratigraphic order) determines spectrum estimation.