1,720,957 research outputs found
Urinary toxicity in patients treated with radical EBRT for prostate cancer: Analysis of predictive factors in an historical series
Get PDFAim and background > The present study aims to identify predictive factors for urinary toxicity and self-reported symptoms after external beam radiotherapy (EBRT) for prostate cancer.Methods > Two-hundred and eighty patients treated with EBRT for prostate cancer were included in the present study. Toxicity was scored following the grading system based on Radiation Therapy Oncology Group (RTOG) scale. International Prostatic Symptom Score (IPSS) and Consultation on Incontinence Questionnaires-Short Form (ICIQ-SF) were used to analyse self-reported symptoms. Acute and late urinary toxicities were correlated to clinical and treatment parameters, radiation dosimetry data, IPSS and ICIQ-SF.Results > Median patient age was 74 years (range, 64-83). Thirty-one percent experienced acute G1 urinary toxicity, 24% G2 and 3% G3. Fourteen percent experienced G1 late urinary toxicity and 3% G2. Bladder volume < 200 cc was associated with acute urinary toxicity (P = 0.014); use of MRI for treatment planning allowed a lower incidence of late toxicity (P = 0.062) and use of IMRT allowed for reduced incidence in late toxicity (P = 0.038). Maximum bladder dose correlated with late urinary toxicity (P = 0.014). The analysis of self-reported symptoms showed a significant correlation between IPSS baseline values (P = 0.009), presence of nocturia (P = 0.002), bladder urgency (P = 0.024) and incontinence (P = 0.024) and development of acute urinary toxicity at univariate analysis. At multivariate logistic regression analysis, bladder filling, IPSS value, nocturia, and urinary incontinence retained significant correlation with acute toxicity (P = 0.0003).Discussion > Significant independent predictors for acute urinary toxicity grade >= 2 were bladder filling, IPSS value, nocturia, and urinary incontinence at baseline assessment
Three-dimensional surface imaging for detection of intra-fraction setup variations during radiotherapy of pelvic tumors
No full textPURPOSE:
Surface-based image guided radiotherapy (IGRT) allows positioning and/or monitoring patients in 3 dimensions (3D), without the use of ionizing radiation. In this study, we report on intra-fraction motion measured by acquisition of multiple images of 3D body surfaces.
MATERIALS AND METHODS:
Twenty-nine patients treated for pelvic tumors were enrolled. Setup variations (SV) through three consecutive body surfaces acquired by the optical IGRT system Align-RT (Vision-RT, London, UK) were analyzed before, during and at the end of treatment delivery. Displacements along the main axes (X, Y and Z) from initial (I) to mid-treatment (MT) and final (F) acquisitions were recorded. Time and direction of SV were assessed.
RESULTS:
A total of 6272 images from 792 fractions of 29 patients were available. The main source of misalignment was between I and MT acquisition (p < 0.001). The dominant SV direction was the vertical one (Z axis), with mean SV of -1.20 ± 0.06 mm and -1.55 ± 0.06 mm for I-MT and I-F acquisitions, respectively. The Y mean components of SV were, respectively, -0.95 ± 0.10 mm and -1.0 ± 0.10 for I-MT and I-F acquisitions, while the X deviations were 0.07 ± 0.08 mm for I-MT and 0.26 ± 0.08 mm I-F.
CONCLUSION:
Three-D surface imaging for patient setup monitoring highlighted remarkable mobility of patients during RT session, especially in the anterior-posterior direction (Z axis). The largest magnitude in patient movements occurred during the first part of delivery. These findings suggest that the initial setup control cannot not to be sufficient to guarantee treatment reproducibility, especially for long-lasting RT treatments
Three-dimensional surface and ultrasound imaging for daily IGRT of prostate cancer
Get PDFBACKGROUND:
Image guided radiotherapy (IGRT) is an essential pre-requisite for delivering high precision radiotherapy. We compared daily variation detected by two non-ionizing imaging modalities (surface imaging and trans-abdominal ultrasound, US) to verify prostate patient setup and internal organ variations.
METHODS:
Forty patients with organ confined prostate cancer and candidates to curative radiotherapy were enrolled in this prospective study. At each treatment session, after laser alignment, all patients received imaging by a 3D-surface and a 3D-US system. The shifts along the three directions (anterior-posterior AP, cranial-caudal CC, and later-lateral LL) were measured in terms of systematic and random errors. Then, we performed statistical analysis on the differences and the possible correlations between the two modalities.
RESULTS:
For both IGRT modalities, surface imaging and US, 1318 acquisitions were collected. According with Shapiro Wilk test, the positioning error distributions were not Gaussian for both modalities. The differences between the systematic errors detected by the two modalities were statistically significant only in LL direction (p < 0.05), while the differences between the random errors were not statistically significant in any directions. The 95% confidence interval of the residual errors obtained by subtracting the random errors detected with surface images to those detected with US was included in the range from -7 mm to 7 mm corresponding to the minimum PTV margin adopted in AP direction in our clinical routine.
CONCLUSIONS:
From our data, it emerges that setup misalignments measured by surface imaging can be predictive of US displacements after the adjustment for systematic errors. Moreover, surface imaging can detect setup errors predictive of registration errors measured by US. This data suggest that the two IGRT modalities could be considered as complementary to each other and could represent a daily "low-cost" and non-invasive IGRT modality in prostate cancer patients
Postoperative radiotherapy in prostate cancer: Analysis of prognostic factors in a series of 282 patients
No full textAIM:
To assess the outcomes of patients treated with postoperative RT in relation to the possible prognostic factors.
BACKGROUND:
Postoperative radiotherapy (RT) has been proved to reduce the risk of biochemical recurrence in high-risk prostate cancer patients. Baseline prostate specific antigen (PSA), pathological Gleason score (GS), positive surgical margins, nodal status and seminal vesicle invasion are independent predictors of biochemical relapse.
MATERIALS AND METHODS:
The clinical records of 282 patients who underwent postoperative RT were retrospectively reviewed. The prognostic value of postoperative PSA, preoperative risk class, nodal status, pathological GS, margins status, and administration of hormonal therapy (HT) was analyzed.
RESULTS:
Postoperative RT was delivered with a median dose to the prostatic fossa of 66 Gy (range 50-72) in 1.8-2 Gy/fraction. Median follow-up was 23.1 months (range 6-119). Five-year actuarial biochemical disease-free survival (bDFS) and overall survival rates were 76% and 95%, respectively. Higher bDFS was found for patients with postoperative PSA <0.02 ng/ml (p = 0.03), low preoperative risk class (p = 0.01), pN0 (p = 0.003), GS 4-6 (p = 0.0006), no androgen deprivation therapy (p = 0.02), and irrespective of surgical margin status (p = 0.10). Multivariate analysis showed that postoperative PSA and Gleason score had a significant impact on bDFS (p = 0.039 and p = 0.05, respectively).
CONCLUSIONS:
Postoperative RT with a dose of 66 Gy offers an acceptable toxicity and an optimal disease control after radical prostatectomy in patients with different risk features. A postoperative PSA >0.02 ng/ml could be considered as a prognostic factor and a tool to select patients at risk for progression
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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