1,720,979 research outputs found
Low and medium doses of hypofractionated stereotactic radiotherapy could be suboptimal for early-stage lung cancer
No full textPurpose: This study aimed to analyze the outcome of low and medium doses of hypofractionated stereotactic body radiotherapy (SBRT) in early stage lung cancer. Methods: Thirty-five early stage lung cancer patients were treated with SBRT. Initially, SBRT was administered with a low dose of 5 x 8Gy in all cases. Subsequently, a medium dose of 5 x 10Gy for peripherally located lesions was given, continuing to prescribe 5 x 8Gy in centrally located ones. Study endpoints were local control (LC), LC duration, survival and toxicity. Results: Patients had a good performance status, and T1-2 stage cancer. The SBRT doses of 5 x 8Gy and 5 x 10Gy were administered to 57% and 43% of patients, respectively. At first evaluation after SBRT, local control was obtained in all cases but only 15 (43%) had a complete response. Median duration of LC was 41 months and there was a trend in favor of 5 x 10Gy with respect to 5 x 8Gy in 2- and 3-year LC rates (93% and 69%, versus 60% and 50%, p = 0.1). Four of the 15 (27%) complete responders had local relapse after a quite long median time of 31.5 months. Median overall survival was 40 months. No examined variables (i.e., dose, volume, T stage, and site) significantly conditioned LC, duration of LC, failure rate and survival. Both SBRT schedules were well tolerated. Conclusion: Outcome of low and medium SBRT doses in terms of LC, duration of LC, patterns of failure and survival was suboptimal compared with recently reported results of SBRT in early stage lung cancer patients
Reirradiation of metastatic spinal cord compression: Definitive results of two randomized trials
No full textPurpose: Incidence, outcome and prognostic factors of metastatic spinal cord compression (MSCC) patients reirradiated for in-field recurrence were analyzed. Radiation therapists' attitude in reirradiate spinal cord relapses, doses adopted and incidence of myelopathy were also examined.Materials and methods: Data deriving from 579 evaluable patients entered two randomized trials on radiotherapy (RT) for MSCC were revised.Results: Twenty-four (4.15%) patients had an in-field recurrence and 12 (50%) were reirradiated. At the time of analysis all reirradiated patients had died. Median time from first and second RI was 5 months (range, 2-31). Six patients received an 8 Gy single-dose, 2 patients 5 x 3 Gy and remaining four patients 2 x 8, 5 x 4, or a single dose of 7 and 4 Gy, respectively. The median cumulative Biologically Effective Dose (BED) calculated was 114.5 Gy(2) (range. 80-120 Gy(2)). Six of seven (85.7%) ambulant patients maintained walking ability, whereas none of five not ambulant patients recovered the function. Median duration of response was 4.5 months (range, 1-24). The effect of reirradiation on motor function was significantly associated with walking capacity before reirradiation. Myelopathy was never recorded.Conclusions: In MSCC reirradiation was safe and effective. Patient walking capacity before reirradiation was the strongest prognostic factor for functional outcome. Reirradiation was given in about one-half of patients with in-field recurrence and different doses and fractionations were used, even though cumulative BED was in all cases <= 120 Gy(2). (C) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 98 (2011) 234-23
Stereotactic radiotherapy for oligometastases in the lymph nodes
No full textEven though systemic therapy is standard treatment for lymph node metastases, metastasis-directed stereotactic radiotherapy (SRT ) seems to be a valid option in oligometastatic patients with a low disease burden. Positron emission tomography-computed tomography (PET -CT ) is the gold standard for assessing metastases to the lymph nodes; co-registration of PET -CT images and planning CT images are the basis for gross tumor volume (GTV ) delineation. Appropriate techniques are needed to overcome target motion. SRT schedules depend on the irradiation site, target volume and dose constraints to the organs at risk (OARs) of toxicity. Although several fractionation schemes were reported, total doses of 48–60 Gy in 4–8 fractions were proposed for mediastinal lymph node SRT, with the spinal cord, esophagus, heart and proximal bronchial tree being the dose limiting OAR s. Total doses ranged from 30 to 45 Gy, with daily fractions of 7–12 Gy for abdominal lymph nodes, with dose limiting OARs being the liver, kidneys, bowel and bladder. SRT on lymph node metastases is safe; late side effects, particularly severe, are rar
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Management of Metastatic Spinal Cord Compression
No full text Metastatic spinal cord compression, diagnosed in 3–7% of cancer patients, is one of the most dreaded complications of metastatic cancer. It is an oncologic emergency, which must be diagnosed early and treated promptly to achieve the best results and avoid progressive pain, paralysis, sensory loss and sphincter incontinence. Patients who are ambulatory at the time of the diagnosis have a higher probability of obtaining good response to treatment and a longer survival. In clinical practice, back pain accompanies metastatic spinal cord compression in most cases, even in patients with no neurologic deficits. Magnetic resonance imaging is the best tool for diagnosing metastatic spinal cord compression and is able to identify spinal cord compression in 32–35% patients with back pain, bone metastases and normal neurologic examination. Moreover, magnetic resonance imaging gives the extension of the lesion, can diagnose other unsuspected clinical metastatic spinal cord compression sites, and is useful for the radiation oncologist in defining the target volume. Radiotherapy is the treatment of choice in most cases, whereas surgery is advised only in selected patients (ie, if stabilization is necessary, if radiotherapy has already been given in the same area, when vertebral body collapse causes bone impingement on the cord or nerve roots, when there are diagnostic doubts, or when computed tomography-guided percutaneous vertebral biopsy cannot be performed). Laminectomy should be abandoned in favor of more aggressive surgery (ie, posterior, anterior, and/or lateral approach, tumor mass resection, and stabilization of the spine). Generally, radiotherapy must be administered 7–10 days after surgery. The optimal radiation schedule has not been defined. However, as recently suggested by some clinical trials, even the hypofractionated radiotherapy regimens are effective and can be used without increasing radiation-induced myelopathy. Moderate doses of dexamethasone should be used in the early phases of therapy. After radiotherapy, spinal recurrence is generally found in sites different from the first compression area. A close post-treatment follow-up is suggested using clinical parameters (pain, motor and sphincter function), and magnetic resonance imaging should be performed only when a second metastatic spinal cord compression and/or myelopathy are clinically suspected. </jats:p
Exploring All Avenues for Radiotherapy in Oligorecurrent Prostate Cancer Disease Limited to Lymph Nodes: A Systematic Review of the Role of Stereotactic Body Radiotherapy
Full text linkStereotactic body radiotherapy (SBRT) is emerging as a treatment option in patients affected by oligorecurrent prostate cancer disease limited to lymph nodes, a subgroup of patients who would otherwise be treated only with androgen deprivation therapy (ADT)
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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