Highlights • SBRT for inoperable pulmonary metastases achieved excellent LC and promising OS. • LC was mainly influenced by BED at both isocenter and periphery. • Important prognostic factors were ...identified for selecting patients for SBRT treatment. • Important prognostic factors for OS were performance status, metastasis diameter and tumor histology. • OS was further significantly affected by number of metastases and time interval between primary tumor diagnosis and SBRT treatment.
Abstract Background and purpose To evaluate whether local tumor control probability (TCP) in stereotactic body radiotherapy (SBRT) varies between lung metastases of different primary cancer sites and ...between primary non-small cell lung cancer (NSCLC) and secondary lung tumors. Materials and methods A retrospective multi-institutional ( n = 22) database of 399 patients with stage I NSCLC and 397 patients with 525 lung metastases was analyzed. Irradiation doses were converted to biologically effective doses (BED). Logistic regression was used for local tumor control probability (TCP) modeling and the second-order bias corrected Akaike Information Criterion was used for model comparison. Results After median follow-up of 19 months and 16 months (n.s.), local tumor control was observed in 87.7% and 86.7% of the primary and secondary lung tumors (n.s.), respectively. A strong dose–response relationship was observed in the primary NSCLC and metastatic cohort but dose–response relationships were not significantly different: the TCD90 (dose to achieve 90% TCP; BED of maximum planning target volume dose) estimates were 176 Gy (151–223) and 160 Gy (123–237) (n.s.), respectively. The dose–response relationship was not influenced by the primary cancer site within the metastatic cohort. Conclusions Dose–response relationships for local tumor control in SBRT were not different between lung metastases of various primary cancer sites and between primary NSCLC and lung metastases.
Many technological and methodical advances have made stereotactic body radiotherapy (SBRT) more accurate and more efficient during the last years. This study aims to investigate whether experience in ...SBRT and technological innovations also translated into improved local control (LC) and overall survival (OS).
A database of 700 patients treated with SBRT for lung metastases in 20 German centers between 1997 and 2014 was used for analysis. It was the aim of this study to investigate the impact of fluorodeoxyglucose positron-emission tomography (FDG-PET) staging, biopsy confirmation, image guidance, immobilization, and dose calculation algorithm, as well as the influence of SBRT experience, on LC and OS.
Median follow-up time was 14.3 months (range, 0-131.9 months), with 2-year LC and OS of 81.2% (95% confidence interval CI 75.8%-85.7%) and 54.4% (95% CI 50.2%-59.0%), respectively. In multivariate analysis, all treatment technologies except FDG-PET staging did not significantly influence outcome. Patients who received pre-SBRT FDG-PET staging showed superior 1- and 2-year OS of 82.7% (95% CI 77.4%-88.6%) and 64.8% (95% CI 57.5%-73.3%), compared with patients without FDG-PET staging resulting in 1- and 2-year OS rates of 72.8% (95% CI 67.4%-78.8%) and 52.6% (95% CI 46.0%-60.4%), respectively (P=.012). Experience with SBRT was identified as the main prognostic factor for LC: institutions with higher SBRT experience (patients treated with SBRT within the last 2 years of the inclusion period) showed superior LC compared with less-experienced centers (P≤.001). Experience with SBRT within the last 2 years was independent from known prognostic factors for LC.
Investigated technological and methodical advancements other than FDG-PET staging before SBRT did not significantly improve outcome in SBRT for pulmonary metastases. In contrast, LC was superior with increasing SBRT experience of the individual center.
Most radiobiological models for prediction of tumor control probability (TCP) do not account for the fact that many events could remain unobserved because of censoring. We therefore evaluated a set ...of TCP models that take into account this censoring.
We applied 2 fundamental Bayesian cure rate models to a sample of 770 pulmonary metastasis treated with stereotactic body radiation therapy at German, Austrian, and Swiss institutions: (1) the model developed by Chen, Ibrahim and Sinha (the CIS99 model); and (2) a mixture model similar to the classic model of Berkson and Gage (the BG model). In the CIS99 model the number of clonogens surviving the radiation treatment follows a Poisson distribution, whereas in the BG model only 1 dominant recurrence-competent tissue mass may remain. The dose delivered to the isocenter, tumor size and location, sex, age, and pretreatment chemotherapy were used as covariates for regression.
Mean follow-up time was 15.5 months (range: 0.1-125). Tumor recurrence occurred in 11.6% of the metastases. Delivered dose, female sex, peripheral tumor location and having received no chemotherapy before RT were associated with higher TCP in all models. Parameter estimates of the CIS99 were consistent with the classical Cox proportional hazards model. The dose required to achieve 90% tumor control after 15.5 months was 146 (range: 114-188) Gy10 in the CIS99 and 133 (range: 101-164) Gy10 in the BG model; however, the BG model predicted lower tumor control at long (≳20 months) follow-up times and gave a suboptimal fit to the data compared to the CIS99 model.
Biologically motivated cure rate models allow adding the time component into TCP modeling without being restricted to the follow-up period which is the case for the Cox model. In practice, application of such models to the clinical setting could allow for adaption of treatment doses depending on whether local control should be achieved in the short or longer term.
Two studies (one longitudinal) were designed to extend Butler's model of teachers' goal orientations for teaching. In Study 1, results from 281 teachers in Germany confirmed the predicted four-factor ...model comprising mastery, ability-approach, ability-avoidance, and work-avoidance goal orientations. As expected, mastery orientation and work avoidance emerged as positive and negative predictors, respectively, of adaptive patterns of instruction (mastery-oriented practices and cognitive stimulation) and high interest in teaching and low burnout; associations for both ability orientations were less consistent. In Study 2, 69 Israeli teachers completed the measures of instructional practices, interest in teaching and burnout several months after reporting their goal orientations. Results were very similar to those of Study 1. The two studies confirm that research on teachers' goal orientation is promising and has implications for understanding how teacher motivation might influence both teachers and their students.
In this work, a mixed integer linear programming (MIP) approach for the optimal design of energy systems in residential buildings is presented. The optimization model considers the economic criteria ...of the guideline VDI 2067. The objective of the MIP is to minimize the annual costs which comprise the investment as well as demand- and operation-related costs. Conventional boilers, electrical heaters, combined heat and power (CHP) units, heat pumps (HPs), photovoltaic (PV) systems and thermal storages as well as local heating networks (HNs) are defined as options. The investigation on a building level shows that a boiler is the economically optimal solution for small buildings, followed by a HP unit. In multi-family buildings, both boilers and CHP units hold an economical advantage over HPs. For apartment buildings, CHP is identified as the economically optimal system. In the neighbourhood analysis of six buildings, the solver establishes a local HN which allows for both economical and CO
2
-emission reductions.
This paper introduces a decentralized scheduling scheme for electro-thermal heating systems i.e. heat pumps and combined heat and power units. The scheduling is modeled as a mixed integer linear ...optimization program (MILP) and reformulated based on the Dantzig–Wolfe decomposition method. The decomposed problem is solved by means of an iterative column generation algorithm that is modified to solve MILPs. The aim is thereby to enhance the integration of renewable energy sources by matching demand and supply. The architecture is based on a cooperative multi-agent system. A centralized scheduling approach is used as a reference to assess the performance of the decentralized concept. The analysis comprises a cluster of existing residential buildings. The results show that the centralized scheduling delivers the best coordination with a limited extendability. The decentralized scheduling presents a slightly lower coordination with a great potential for scalability. Moreover, the decentralized scheduling is based on an emphasized local intelligence which allows for reducing the communication of sensible data.
•Scheduling based energy management concept.•Matching supply and demand from decentralized energy systems.•Enhancing the integration of renewable energy sources.•MILP based on Dantzig–Wolfe decomposition and a column generation algorithm.•MAS enabling robustness, extendibility and scalability as well as data privacy.
Es wird über die Entwicklung eines neuen Fragebogens zur Erfassung des fachlichen, didaktischen und erzieherischen Interesses von Lehrkräften berichtet. In einer Stichprobe von 281 Lehrkräften ...verschiedener Grund-, Haupt- und Gymnasialschulen wurden die Zusammenhänge der drei Interessendimensionen mit der beruflichen Erlebensqualität (Burnout, Vergnügen, Flow) und dem Instruktionsverhalten untersucht. Konfirmatorische Faktorenanalysen bestätigten die dreidimensionale Struktur des neuen Fragebogens. Belege für die Konstruktvalidität ergaben sich aufgrund von Strukturgleichungsanalysen, die zeigten, dass das Interesse Beiträge zur Vorhersage von beruflichem Erleben und Instruktionsverhalten leistet, auch wenn Selbstwirksamkeitsüberzeugungen kontrolliert wurden. Im Einzelnen gingen das didaktische und das erzieherische Interesse mit geringerem Burnout einher und erwiesen sich als Prädiktoren förderlichen Instruktionsverhaltens (z. B. kognitive Aktivierung). Darüber hinaus trugen das fachliche und das erzieherische Interesse zur Vorhersage von Vergnügen und Flow im Unterricht bei. (DIPF/Orig.).
This study introduced a new questionnaire on subject, didactic, and educational teacher interest and analyzed their relations to occupational well-being (burnout, enjoyment, flow) and instructional practices in a sample of 281 teachers from elementary and both low- and high-achievement secondary schools. Results of confirmatory factor analysis verified the three-dimensional structure of the newly developed interest measure. Evidence for the construct validity of the interest measure was provided by structural equation analyses showing that teachers' occupational well-being and instructional practices were predicted by their interests, even when controlling for self-efficacy beliefs. Specifically, both didactic and educational interest contributed to lower levels of burnout and predicted beneficial instructional practices (e.g., cognitive stimulation). In addition, subject and educational interest were the main predictors of enjoyment and flow in class. (DIPF/Orig.).
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