159 resultados para . neutron radiation field
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This study reports on the development and characterization of bovine serum albumin (BSA) nanospheres containing Silicon(IV) phthalocyanine (NzPc) and/or maghemite nanoparticles (MNP), the latter introduced via ionic magnetic fluid (MF). The nanosized BSA-loaded samples were designed for synergic application while combining Photodynamic Therapy and Hyperthermia. Incorporation of MNP in the albumin-based template, allowing full control of the magnetic content, was accomplished by adding a highly-stable ionic magnetic fluid sample to the albumin suspension, following heat denaturing. The material`s evaluation was performed using Zeta potential measurements and scanning electron microscopy. The samples were characterized by steady-state techniques and time-resolved fluorescence. The in vitro assay, using human fibroblasts, revealed no cytotoxic effect in all samples investigated, demonstrating the potential of the tested system as a synergistic drug delivery system.
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Purpose: To evaluate the risk of geographic miss associated with the classic four-field ""box"" irradiation technique and to define the variables that predict this risk. Materials and Methods: The study population consisted of 80 patients with uterine cervix cancer seen between 2001 and 2006. Median age was 55 years (23-82 years), and 72 (90%) presented with squamous cell carcinoma. Most patients (68.7%) presented with locally advanced disease (IIb or more). Magnetic resonance imaging findings from before treatment were compared with findings from simulation of the conventional four-field ""box"" technique done with rectal contrast. Study variables included tumor volume; involvement of vagina, parametrium, bladder, or rectum; posterior displacement of the anterior rectal wall; and tumor anteroposterior diameter (APD). Margins were considered adequate when the target volume (primary tumor extension, whole uterine body, and parametrium) was included within the field limits and were at least 1 cm in width. Results: Field limits were inadequate in 45 (56%) patients: 29 (36%) patients at the anterior and 28 (35%) at the posterior border of the lateral fields. Of these, 12 patients had both anterior and posterior miss, and this risk was observed in all stages of the disease (p = 0.076). Posterior displacement of the anterior rectal wall beyond S2-S3 was significantly correlated with the risk of geographic miss (p = 0.043). Larger tumors (APD 6 cm or above and volume above 50 cm(3)) were also significantly correlated with this risk (p = 0.004 and p = 0.046, respectively). Conclusions: Posterior displacement of the anterior rectal wall, tumor APD, and volume can be used as guidance in evaluating the risk of geographic miss. (C) 2009 Elsevier Inc.
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Purpose The aim of this study was to test the correlation between Fourier-domain (FD) optical coherence tomography (OCT) macular and retinal nerve fibre layer (RNFL) thickness and visual field (VF) loss on standard automated perimetry (SAP) in chiasmal compression. Methods A total of 35 eyes with permanent temporal VF defects and 35 controls underwent SAP and FD-OCT (3D OCT-1000; Topcon Corp.) examinations. Macular thickness measurements were averaged for the central area and for each quadrant and half of that area, whereas RNFL thickness was determined for six sectors around the optic disc. VF loss was estimated in six sectors of the VF and in the central 16 test points in the VF. The correlation between VF loss and OCT measurements was tested with Spearman`s correlation coefficients and with linear regression analysis. Results Macular and RNFL thickness parameters correlated strongly with SAP VF loss. Correlations were generally stronger between VF loss and quadrantic or hemianopic macular thickness than with sectoral RNFL thickness. For the macular parameters, we observed the strongest correlation between macular thickness in the inferonasal quadrant and VF loss in the superior temporal central quadrant (rho=0.78; P<0.001) whereas for the RNFL parameters the strongest correlation was observed between the superonasal optic disc sector and the central temporal VF defect (rho=0.60; P<0.001).
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Neutron activation analysis was applied to assess trace elements concentrations in head hair from healthy elderly people living in the Sao Paulo metropolitan area. Concentrations of As, Br, Ca, Cl, Co, Cr, Cu, Fe, K, La, Mn, Na, Sb, Se and, Zn were determined. Comparisons were made between the results obtained for dyed and non-dyed hair as well as for hair from females and males of two different age groups. The results were also compared with range values established by clinical laboratories and published data.
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Radiation dose calculations in nuclear medicine depend on quantification of activity via planar and/or tomographic imaging methods. However, both methods have inherent limitations, and the accuracy of activity estimates varies with object size, background levels, and other variables. The goal of this study was to evaluate the limitations of quantitative imaging with planar and single photon emission computed tomography (SPECT) approaches, with a focus on activity quantification for use in calculating absorbed dose estimates for normal organs and tumors. To do this we studied a series of phantoms of varying complexity of geometry, with three radionuclides whose decay schemes varied from simple to complex. Four aqueous concentrations of (99m)Tc, (131)I, and (111)In (74, 185, 370, and 740 kBq mL(-1)) were placed in spheres of four different sizes in a water-filled phantom, with three different levels of activity in the surrounding water. Planar and SPECT images of the phantoms were obtained on a modern SPECT/computed tomography (CT) system. These radionuclides and concentration/background studies were repeated using a cardiac phantom and a modified torso phantom with liver and ""tumor"" regions containing the radionuclide concentrations and with the same varying background levels. Planar quantification was performed using the geometric mean approach, with attenuation correction (AC), and with and without scatter corrections (SC and NSC). SPECT images were reconstructed using attenuation maps (AM) for AC; scatter windows were used to perform SC during image reconstruction. For spherical sources with corrected data, good accuracy was observed (generally within +/- 10% of known values) for the largest sphere (11.5 mL) and for both planar and SPECT methods with (99m)Tc and (131)I, but were poorest and deviated from known values for smaller objects, most notably for (111)In. SPECT quantification was affected by the partial volume effect in smaller objects and generally showed larger errors than the planar results in these cases for all radionuclides. For the cardiac phantom, results were the most accurate of all of the experiments for all radionuclides. Background subtraction was an important factor influencing these results. The contribution of scattered photons was important in quantification with (131)I; if scatter was not accounted for, activity tended to be overestimated using planar quantification methods. For the torso phantom experiments, results show a clear underestimation of activity when compared to previous experiment with spherical sources for all radionuclides. Despite some variations that were observed as the level of background increased, the SPECT results were more consistent across different activity concentrations. Planar or SPECT quantification on state-of-the-art gamma cameras with appropriate quantitative processing can provide accuracies of better than 10% for large objects and modest target-to-background concentrations; however when smaller objects are used, in the presence of higher background, and for nuclides with more complex decay schemes, SPECT quantification methods generally produce better results. Health Phys. 99(5):688-701; 2010
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Purpose: Erlotinib, an oral tyrosine kinase inhibitor, is active against head-and-neck squamous cell carcinoma (HNSCC) and possibly has a synergistic interaction with chemotherapy and radiotherapy. We investigated the safety and efficacy of erlotinib added to cisplatin and radiotherapy in locally advanced HNSCC. Methods and Materials: In this Phase I/II trial 100 mg/m(2) of cisplatin was administered on Days 8, 29, and 50, and radiotherapy at 70 Gy was started on Day 8. During Phase I, the erlotinib dose was escalated (50 mg, 100 mg, and 150 mg) in consecutive cohorts of 3 patients, starting on Day 1 and continuing during radiotherapy. Dose-limiting toxicity was defined as any Grade 4 event requiring radiotherapy interruptions. Phase 11 was initiated 8 weeks after the last Phase I enrollment. Results: The study accrued 9 patients in Phase I and 28 in Phase II; all were evaluable for efficacy and safety. No dose-limiting toxicity occurred in Phase I, and the recommended Phase 11 dose was 150 mg. The most frequent nonhematologic toxicities were nausea/vomiting, dysphagia, stomatitis, xerostomia and in-field dermatitis, acneiform rash, and diarrhea. Of the 31 patients receiving a 150-mg daily dose of erlotinib, 23 (74%; 95% confidence interval, 56.8%-86.3%) had a complete response, 3 were disease free after salvage surgery, 4 had inoperable residual disease, and 1 died of sepsis during treatment. With a median 37 months` follow-up, the 3-year progression-free and overall survival rates were 61% and 72%, respectively. Conclusions: This combination appears safe, has encouraging activity, and deserves further studies in locally advanced HNSCC. (C) 2010 Elsevier Inc.
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Gamma and beta radiation emitting radiopharmaceuticals are handled in nuclear medicine services, and in many cases there is only individual monitoring of gamma radiation. In this paper, the results obtained using a wrist dosimeter prototype (CaSO(4):Dy + Teflon pellets) show that the doses for workers occupationally exposed to beta radiation from (153)Sm are not negligible. It is important that this dose is evaluated, and it has to be taken into consideration in the individual monitoring system.
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Objective: To determine intraocular pressure (IOP)-dependent and IOP-independent variables associated with visual field (VF) progression in treated glaucoma. Design: Retrospective cohort of the Glaucoma Progression Study. Methods: Consecutive, treated glaucoma patients with repeatable VF loss who had 8 or more VF examinations of either eye, using the Swedish Interactive Threshold Algorithm (24-2 SITA-Standard, Humphrey Field Analyzer II; Carl Zeiss Meditec, Inc, Dublin, California), during the period between January 1999 and September 2009 were included. Visual field progression was evaluated using automated pointwise linear regression. Evaluated data included age, sex, race, central corneal thickness, baseline VF mean deviation, mean follow-up IOP, peak IOP, IOP fluctuation, a detected disc hemorrhage, and presence of beta-zone parapapillary atrophy. Results: We selected 587 eyes of 587 patients (mean [SD] age, 64.9 [13.0] years). The mean (SD) number of VFs was 11.1 (3.0), spanning a mean (SD) of 6.4 (1.7) years. In the univariable model, older age (odds ratio [OR], 1.19 per decade; P = .01), baseline diagnosis of exfoliation syndrome (OR, 1.79; P = .01), decreased central corneal thickness (OR, 1.38 per 40 mu m thinner; P < .01), a detected disc hemorrhage (OR, 2.31; P < .01), presence of beta-zone parapapillary atrophy (OR, 2.17; P < .01), and all IOP parameters (mean follow-up, peak, and fluctuation; P < .01) were associated with increased risk of VF progression. In the multivariable model, peak IOP (OR, 1.13; P < .01), thinner central corneal thickness (OR, 1.45 per 40 mu m thinner; P < .01), a detected disc hemorrhage (OR, 2.59; P < .01), and presence of beta-zone parapapillary atrophy (OR, 2.38; P < .01) were associated with VF progression. Conclusions: IOP-dependent and IOP-independent risk factors affect disease progression in treated glaucoma. Peak IOP is a better predictor of progression than is IOP mean or fluctuation.
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The present study was carried out to evaluate the effectiveness of a specific program regarding the occurrence of vocal attrition symptoms in telemarketers. A total of 71 subjects participated in this study: 28 completed the Vocal Symptoms questionnaire to test its reliability, and 43 were randomly assigned to two groups: an 8-week vocal training group (n = 14) and a no-training control group (n = 29), to evaluate the effectiveness of the training program with this tool. The voice training group also filled in the posttraining questionnaire `Benefits Obtained with Voice Training` (BVT). The vocal training program was not considered effective with regard to the occurrence of vocal symptoms. However, due to a probable increase in symptoms in untrained telemarketers, it can work as a protective factor. According to BVT answers, the vocal training contributed to an improvement in vocal use as a communication tool for telemarketers. Copyright (C) 2009 S. Karger AG, Basel
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BACKGROUND: Among the various occupations which necessarily require long-term and chronic sun exposure is that of a fisherman. However, clinical experience in dermatology earned over several years of medical practice does not seem to confirm this hypothesis. OBJECTIVE: To evaluate clinical, histological and immunological effects of long-term and chronic exposure to ultraviolet radiation in fishermen. METHODS: A prospective, cross-sectional and observational study characterized skin lesions, immunological markers and histological alterations in fishermen, as well as lymphocyte subpopulations compared to a control group. Mann-Whitney, Fisher`s and Wilcoxon statistical tests were used at a significance level of 0.05. RESULTS: There were significant differences between the exposed group and the group protected due to elastosis (p = 0.03), ectasia of dermal vessels (p = 0.012) and number of cells in the epidermal layers between cones (p = 0.029). Most common among fishermen were CD45RO, CD68 + and mastocytes in the skin (p = 0.040, p < 0.001, p = 0.001) and CD3CD8CD45RO in the blood (p = 0.016). CONCLUSION: The alterations suggest that long-term and chronic sun exposure promotes tolerance to ultraviolet radiation, which protects against immunosuppression.
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Epidemiological studies have demonstrated the adverse effects of particulate matter (PM) inhalation on the respiratory and cardiovascular systems. It has been reported that air pollution may affect the central nervous system and decrease cognitive function. In rats, residual oil fly ash (ROFA) instillation causes decreased motor activity and increased lipid peroxidation in the striatum and the cerebellum. Our objective was to determine whether chronic instillation of particles induces changes in learning and memory in rats and whether oxidants in the hippocampus may contribute to these adverse effects. Forty-five-day-old male Wistar rats were exposed to ROFA by intranasal instillation and were treated with N-acetylcysteine (NAC) at 150 mg/kg i.p. for 30 days. Control groups were exposed to ROFA, NAC, or neither. On days 1, 8, and 30 of the protocol, rats were submitted to the open field test to evaluate habituation. After the last open field session, the rats were killed by decapitation. The hippocampus was used to determine lipid peroxidation (LP) by the thiobarbituric acid-reactive substances test. ROFA instillation induced an increase in LP in the hippocampus compared to all treatment groups (p = .012). NAC treatment blocked these changes. All of the treatment groups presented a decrease in the frequency of peripheral walking (p = .001), rearing (p = .001), and exploration (p = .001) over time. Our study demonstrates that exposure to particles for 30 days and/or NAC treatment do not modify habituation to an open field, a simple form of learning and memory in rats, and that oxidative damage induced by ROFA does not modulate these processes.
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Purpose: To evaluate rates of visual field progression in eyes with optic disc hemorrhages and the effect of intraocular pressure (IOP) reduction on these rates. Design: Observational cohort study. Participants: The study included 510 eyes of 348 patients with glaucoma who were recruited from the Diagnostic Innovations in Glaucoma Study (DIGS) and followed for an average of 8.2 years. Methods: Eyes were followed annually with clinical examination, standard automated perimetry visual fields, and optic disc stereophotographs. The presence of optic disc hemorrhages was determined on the basis of masked evaluation of optic disc stereophotographs. Evaluation of rates of visual field change during follow-up was performed using the visual field index (VFI). Main Outcome Measures: The evaluation of the effect of optic disc hemorrhages on rates of visual field progression was performed using random coefficient models. Estimates of rates of change for individual eyes were obtained by best linear unbiased prediction (BLUP). Results: During follow-up, 97 (19%) of the eyes had at least 1 episode of disc hemorrhage. The overall rate of VFI change in eyes with hemorrhages was significantly faster than in eyes without hemorrhages (-0.88%/year vs. -0.38%/year, respectively, P < 0.001). The difference in rates of visual field loss pre- and post-hemorrhage was significantly related to the reduction of IOP in the post-hemorrhage period compared with the pre-hemorrhage period (r = -0.61; P < 0.001). Each 1 mmHg of IOP reduction was associated with a difference of 0.31%/year in the rate of VFI change. Conclusions: There was a beneficial effect of treatment in slowing rates of progressive visual field loss in eyes with optic disc hemorrhage. Further research should elucidate the reasons why some patients with hemorrhages respond well to IOP reduction and others seem to continue to progress despite a significant reduction in IOP levels. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2010; 117: 2061-2066 (C) 2010 by the American Academy of Ophthalmology.
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OBJECTIVES To describe the use of pulsed fluoroscopic guidance, to perform endoscopic procedures in pregnant women, by inverting the fluoroscope`s c-arm using a lead thyroid collar to shield the fetus from the direct X-ray beam. The use of radiation during treatment of pregnant patients with urolithiasis remains a recurring dilemma. METHODS Between May 2006 and December 2008, endoscopic treatment due to ureteral stones was attempted in 8 pregnant women. In all cases, we use an inverted fluoroscope`s c-arm during endoscopic treatment associated with 2 lead neck thyroid collars to shield the uterus, protecting the fetus from direct radiation. Indication for treatment was symptomatic ureteral stones unresponsive to medical treatment in 7 and persistent fever in 1. RESULTS Mean ureteral stone size was 8.1 +/- 4.8 mm, located in the left ureter in 5 (62.5%) cases. Three (37.5%) patients had stone located in the upper ureter, 2 (25%) in the middle ureter, and 3 (37.5) in the distal ureter. In 6 cases, ureteral stones were treated using the semi-rigid ureteroscope, whereas in 1 case a flexible ureteroscope was needed. One woman was treated with insertion of a double-J stent due to associated urinary infection. No women has early delivery related to the endoscopic procedure, and all neonates were perfectly normal. CONCLUSIONS We present a technique for endoscopic procedures in pregnant women inverting the fluoroscope`s c-arm and protecting the fetus from the direct X-ray beam. This practical approach should be specially considered when no portable ultrasound and radiologic assistance in available in the operating room. UROLOGY 75: 1505-1508, 2010. (c) 2010 Published by Elsevier Inc.
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Background: Oncologic outcomes in men with radiation-recurrent prostate cancer (PCa) treated with salvage radical prostatectomy (SRP) are poorly defined. Objective: To identify predictors of biochemical recurrence (BCR), metastasis, and death following SRP to help select patients who may benefit from SRP. Design, setting, and participants: This is a retrospective, international, multi-institutional cohort analysis. There was amedian follow-up of 4.4 yr following SRP performed on 404 men with radiation-recurrent PCa from 1985 to 2009 in tertiary centers. Intervention: Open SRP. Measurements: BCR after SRP was defined as a serum prostate-specific antigen (PSA) >= 0.1 or >= 0.2 ng/ml (depending on the institution). Secondary end points included progression to metastasis and cancerspecific death. Results and limitations: Median age at SRP was 65 yr of age, and median pre-SRP PSA was 4.5 ng/ml. Following SRP, 195 patients experienced BCR, 64 developed metastases, and 40 died from PCa. At 10 yr after SRP, BCR-free survival, metastasis-free survival, and cancer-specific survival (CSS) probabilities were 37% (95% confidence interval [CI], 31-43), 77% (95% CI, 71-82), and 83% (95% CI, 76-88), respectively. On preoperative multivariable analysis, pre-SRP PSA and Gleason score at postradiation prostate biopsy predicted BCR (p = 0.022; global p < 0.001) and metastasis (p = 0.022; global p < 0.001). On postoperative multivariable analysis, pre-SRP PSA and pathologic Gleason score at SRP predicted BCR (p = 0.014; global p < 0.001) and metastasis (p < 0.001; global p < 0.001). Lymph node involvement (LNI) also predicted metastasis (p = 0.017). The main limitations of this study are its retrospective design and the follow-up period. Conclusions: In a select group of patients who underwent SRP for radiation-recurrent PCa, freedom from clinical metastasis was observed in > 75% of patients 10 yr after surgery. Patients with lower pre-SRP PSA levels and lower postradiation prostate biopsy Gleason score have the highest probability of cure from SRP. (C) 2011 European Association of Urology. Published by Elsevier B. V. All rights reserved.
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Neutron activation analysis was applied to assess trace element concentrations in brain tissues from normal (n = 21) and demented individuals (n = 21) of both genders aged more than 50 years. Concentrations of the elements Br, Fe, K, Na, Rb, Se and Zn were determined. Comparisons were made between the results obtained for the hippocampus and frontal cortex tissues, as well as, those obtained in brains of normal and demented individuals. Certified reference materials, NIST 1566b Oyster Tissue and NIST 1577b Bovine Liver were analyzed for quality of the analytical results.