967 resultados para cosmic background radiation
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Summary
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BACKGROUND: Cardiac toxicity is a side-effect of anti-cancer treatment including radiotherapy and this translational study was initiated to characterize radiation-induced cardiac side effects in a population of breast cancer patients and in experimental models in order to identify novel therapeutic target. METHODS: The size of the heart was evaluated in CO-HO-RT patients by measuring the Cardiac-Contact-Distance before and after radiotherapy (48months of follow-up). In parallel, fibrogenic signals were studied in a severe case of human radiation-induced pericarditis. Lastly, radiation-induced cardiac damage was studied in mice and in rat neonatal cardiac cardiomyocytes. RESULTS: In patients, time dependent enhancement of the CCD was measured suggesting occurrence of cardiac hypertrophy. In the case of human radiation-induced pericarditis, we measured the activation of fibrogenic (CTGF, RhoA) and remodeling (MMP2) signals. In irradiated mice, we documented decreased contractile function, enlargement of the ventricular cavity and long-term modification of the time constant of decay of Ca(2+) transients. Both hypertrophy and amyloid deposition were correlated with the induction of Epac-1; whereas radiation-induced fibrosis correlated with Rho/CTGF activation. Transactivation studies support Epac contribution in hypertrophy stimulation and showed that radiotherapy and Epac displayed specific and synergistic signals. CONCLUSION: Epac-1 has been identified as a novel regulator of radiation-induced hypertrophy and amyloidosis but not fibrosis in the heart.
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Background and Aims The frequency at which males can be maintained with hermaphrodites in androdioecious populations is predicted to depend on the selfing rate, because self-fertilization by hermaphrodites reduces prospective siring opportunities for males. In particular, high selfing rates by hermaphrodites are expected to exclude males from a population. Here, the first estimates are provided of the mating system from two wild hexaploid populations of the androdioecious European wind-pollinated plant M. annua with contrasting male frequencies.Methods Four diploid microsatellite loci were used to genotype 19-20 progeny arrays from two populations of M. annua, one with males and one without. Mating-system parameters were estimated using the program MLTR.Key Results Both populations had similar, intermediate outcrossing rates (t(m) = 0.64 and 0.52 for the population with and without males, respectively). The population without males showed a lower level of correlated paternity and biparental inbreeding and higher allelic richness and gene diversity than the population with males.Conclusions The results demonstrate the utility of new diploid microsatellite loci for mating system analysis in a hexaploid plant. It would appear that androdioecious M. annua has a mixed-mating system in the wild, an uncommon finding for wind-pollinated species. This study sets a foundation for future research to assess the relative importance of the sexual system, plant-density variation and stochastic processes for the regulation of male frequencies in M. annua over space and time.
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OBJECTIVE: Examination of the rate of grade III or grade IV radiation dermatitis during treatment of head and neck cancer (HNC) with radiotherapy (RT) and concurrent cetuximab in EORTC centres. MATERIALS AND METHOD: A questionnaire was sent to all members of the EORTC Radiation Oncology Group and Head and Neck Group (111 institutions) to evaluate the widespread use of cetuximab and radiotherapy in HNC and to estimate the frequency of grades III and IV skin reactions in the radiation portals associated with this protocol. Co-morbidities, RT schedules and co-medications were also recorded. RESULTS: We received responses from 28 institutions in 11 countries. A total of 125 HNC patients from 15 institutions were treated with cetuximab and concurrent RT. Information about the skin reactions was available from 71 patients. Of these 36 had no grade III/IV adverse effects in the RT field, 15 had a grade III and 20 had grade IV radiation dermatitis. No detectable relation of grades III and IV radiation dermatitis with co-morbidities such as liver insufficiency or renal dysfunction was found. CONCLUSION: According to the results of the questionnaire, grade III/IV radiation dermatitis is observed in 49% of HNC patients treated with cetuximab and concurrent RT. A systematic clinical monitoring of cutaneous side effects during RT plus cetuximab is advised to ensure the safety of this protocol.
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Background: Post-surgical management of stage I seminoma includes: surveillance with repeated CT-scans and treatment reserved for those who relapse, or adjuvant treatment with either immediate radiation therapy (RT) or carboplatin. The cancer specific survival is close to 100%. Cure without long-term sequelae of treatment is the aim. Our goal is to estimate the risk of radiation-induced secondary cancers (SC) death from for patients undergoing S, adjuvant RT or adjuvant carboplatin (AC).Materials and Methods: We measured organ doses from CT scans (3 phases each one) of a seminoma patient who was part of the active surveillance strategy and from a man undergoing adjuvant RT 20-Gy and a 30-Gy salvage RT treatment to the para-aortic area using helical Intensity Modulated RT (Tomotherapy®) with accurate delineation of organs at risk and a CTV to PTV expansion of 1 cm. Effective doses to organs in mSv were estimated according to the tissue-weighting factors recommendations of the International Commission on Radiological Protection 103 (Ann ICRP 2007). We estimated SC incidence and mortality for a 10,000 people population based on the excess absolute risk model from the Biological Effects of Ionizing Radiation (BEIR) VII (Health Risk of Exposure to Low Levels of Ionizing Radiation, NCR, The National Academies Press Washington, DC, 2006) assuming a seminoma diagnosis at age 30, a total life expectancy of 80 years.Results: The nominal risk for a fatal secondary cancers was calculated 1.5% for 15 abdominal CT scans, 14.8% for adjuvant RT (20 Gy paraaortic field) and 22.2% for salvage RT (30 Gy). The calculation assumed that the risk of relapse on surveillance and adjuvant AC was 15% and 4% respectively and that all patients were salvaged at relapse with RT. n CT abdomen/Pelvis = secondary cancer % RT Dose and % receiving treatment = secondary cancer % Total secondary cancer risk in % Active surveillance 15 = 1.5% 30 Gy in 15% of pts = 3.3% 4.8 Adjuvant carboplatin 7 = 0.7% 30 Gy in 4% of pts = 0.88% 1.58 Adjuvant radiotherapy 7 = 0.7% 20 Gy in 100% of pts = 14.8% 15.5Conclusions: These data suggest that: 1) Adjuvant radiotherapy is harmful and should not anymore be regarded as a standard option for seminoma stage I. 2) AC seems to be an option to reduce radiation induced cancers. Limitations: the study does not consider secondary cancers due to chemotherapy with AC (unknown). The use of BEIR VII for risk modeling with higher doses of RT needs to be validated.
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PURPOSE: Ocular anatomy and radiation-associated toxicities provide unique challenges for external beam radiation therapy. For treatment planning, precise modeling of organs at risk and tumor volume are crucial. Development of a precise eye model and automatic adaptation of this model to patients' anatomy remain problematic because of organ shape variability. This work introduces the application of a 3-dimensional (3D) statistical shape model as a novel method for precise eye modeling for external beam radiation therapy of intraocular tumors. METHODS AND MATERIALS: Manual and automatic segmentations were compared for 17 patients, based on head computed tomography (CT) volume scans. A 3D statistical shape model of the cornea, lens, and sclera as well as of the optic disc position was developed. Furthermore, an active shape model was built to enable automatic fitting of the eye model to CT slice stacks. Cross-validation was performed based on leave-one-out tests for all training shapes by measuring dice coefficients and mean segmentation errors between automatic segmentation and manual segmentation by an expert. RESULTS: Cross-validation revealed a dice similarity of 95% ± 2% for the sclera and cornea and 91% ± 2% for the lens. Overall, mean segmentation error was found to be 0.3 ± 0.1 mm. Average segmentation time was 14 ± 2 s on a standard personal computer. CONCLUSIONS: Our results show that the solution presented outperforms state-of-the-art methods in terms of accuracy, reliability, and robustness. Moreover, the eye model shape as well as its variability is learned from a training set rather than by making shape assumptions (eg, as with the spherical or elliptical model). Therefore, the model appears to be capable of modeling nonspherically and nonelliptically shaped eyes.
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OBJECTIVE: The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose. SUBJECTS AND METHODS: Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions. RESULTS: With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage. CONCLUSION: The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.
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Background And Objectives: Isolated limb perfusion with TNF-alpha and melphalan (TM-ILP) is a limb salvage therapy for non-resectable soft tissue sarcomas (STS) of the extremities. It is indicated for patients for whom amputation or debilitating surgery is the only alternative. It can be used either as an exclusive therapy (in palliation) or as a neo-adjuvant treatment, followed by marginal resection of tumor remnants with minimal functional impairment. Methods: Between February 1992 and March 2006, 57 TM-ILPs were performed on 51 patients with 88% high grade and 84% advanced stage tumors. Results: Mean follow-up is 38.9 months (4-159, median 22 months). Twenty-one percent patients had significant early complications, with 3 major re-operations, and 23% suffered long-lasting complications. Complete response was observed in 25%, partial response in 42%, stable disease in 14% and progressive disease in 14%. Resection of the tumor remnants was possible in 65%. A complementary treatment was necessary in 31%, mostly radiation therapy. A local recurrence was observed in 35%, after a mean of 20.3 months (2-78), and distant relapse was seen in 45%, after a mean of 13.4 months (5-196). Mean Disease-free survival was 14.9 months, and overall 5-year-survival 43.5%. Amputation rate at 5 years was 24%. Conclusions: TM-ILP is a conservative treatment with a high complications rate, but it can be successful even for the most severe STS of extremities. As a consequence the limb can be spared from amputation or debilitating surgery on the long term in about 75% of patients
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Purpose. To evaluate the impact of mobile devices and apps on the daily clinical activity of young radiation oncologists. Methods. A web-based questionnaire was sent to 382 young (≤40 years) members of the Italian Association of Radiation Oncology (AIRO). The 14 items investigated the diffusion of mobile devices (smartphones and/or tablets), their impact on daily clinical activity, and possible differences perceived by the participants over time. Results. A total of 158 questionnaires were available for statistical evaluation (response rate 41%). Up to 75% of respondents declared they used an electronic device during their clinical activity. Conversely, 82% considered the impact of smartphones/tables on daily practice low to moderate. Daily device use increased significantly from 2009 to 2012, with high daily use rates rising from 5% to 39.9%. Fulfillment of professional needs was declared by less than 42% of respondents and compliance with app indications by 32%. Almost all physicians desired in 2012 a comprehensive website concerning a variety of apps covering radiation oncologists' needs. Conclusions. Mobile devices are widely used by young Italian radiation oncologists in their daily clinical practice, while the indications so obtained are not always followed. Nevertheless, it would be important to verify the consistency of information found within apps, in order to avoid potential errors that might be detrimental to patients.
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BACKGROUND: A combination of radioimmunotherapy (RIT) and radiotherapy (RT) should allow one to increase the dose of radiation targeting a particular tumour without the concomitant increase of toxic side effects. This might be obtained if the dose limiting side effect of each individual radiation therapy concerned different organs. METHODS: Six patients with limited liver metastatic disease from colorectal cancer were treated with 6.9 GBq (range 4.7 to 8.4 GBq) 131I-labelled anti-CEA MAb F(ab')2 fragments combined with 20 Gy RT to the liver. Both treatments were given in close association, according to timing schedules evaluated in animals that gave the best results. RESULTS: Reversible bone marrow and liver toxicity was observed in 6 and 5 patients, respectively. Three patients who first received 20 Gy RT to the liver, showed a significant platelet drop upon completion of RT. Repeat computerized tomography (CT) after 2 months showed a minor response in 1 patient and stable disease in 3 patients. CONCLUSION: The study shows potential ways of combining RIT and RT, suggesting that this combination is feasible for the treatment of liver metastases.
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A nation-wide survey on radiation doses in diagnostic and interventional radiology was conducted in Switzerland in 1998 aiming at establishing their collective radiological impact on the Swiss population. The study consisted on the one hand of surveying the frequency of more than 250 types of examinations, covering conventional radiology, mammography, fluoroscopy, angiography, interventional radiology, CT, bone densitometry, conventional tomography and dental radiology. On the other hand, for each type of examination the associated patient dose was established by modeling. The results of this study show that about 9.5 million diagnostic and interventional examinations are performed annually in Switzerland (1.34 per caput) and that the associated annual collective dose is of the order of 7100 person.Sv (1.0 mSv per caput). Switzerland is similar to other European countries in terms of the frequency of examinations and the collective dose.
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This article expresses the current view of the European Society of Gastrointestinal Endoscopy (ESGE) about radiation protection for endoscopic procedures, in particular endoscopic retrograde cholangiopancreatography (ERCP). Particular cases, including pregnant women and pediatric patients, are also discussed. This Guideline was developed by a group of endoscopists and medical physicists to ensure that all aspects of radiation protection are adequately dealt with. A two-page executive summary of evidence statements and recommendations is provided. The target readership for this Guideline mostly includes endoscopists, anesthesiologists, and endoscopy assistants who may be exposed to X-rays during endoscopic procedures.
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INTRODUCTION: Adaptive statistical iterative reconstruction (ASIR) can decrease image noise, thereby generating CT images of comparable diagnostic quality with less radiation. The purpose of this study is to quantify the effect of systematic use of ASIR versus filtered back projection (FBP) for neuroradiology CT protocols on patients' radiation dose and image quality. METHODS: We evaluated the effect of ASIR on six types of neuroradiologic CT studies: adult and pediatric unenhanced head CT, adult cervical spine CT, adult cervical and intracranial CT angiography, adult soft tissue neck CT with contrast, and adult lumbar spine CT. For each type of CT study, two groups of 100 consecutive studies were retrospectively reviewed: 100 studies performed with FBP and 100 studies performed with ASIR/FBP blending factor of 40 %/60 % with appropriate noise indices. The weighted volume CT dose index (CTDIvol), dose-length product (DLP) and noise were recorded. Each study was also reviewed for image quality by two reviewers. Continuous and categorical variables were compared by t test and free permutation test, respectively. RESULTS: For adult unenhanced brain CT, CT cervical myelography, cervical and intracranial CT angiography and lumbar spine CT both CTDIvol and DLP were lowered by up to 10.9 % (p < 0.001), 17.9 % (p = 0.005), 20.9 % (p < 0.001), and 21.7 % (p = 0.001), respectively, by using ASIR compared with FBP alone. Image quality and noise were similar for both FBP and ASIR. CONCLUSION: We recommend routine use of iterative reconstruction for neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality.