A dosimetry evaluation of 90y-stent implantation in intracoronary radiation treatment

Ionizing particles have been used for the treatment of atherosclerosis. Internal irradiation is commonly carried out by means of several methods (catheter-based systems, radioactive stents or balloons) to reduce the probability of restenosis. 90Y, due to some of its characteristics, is an appropriate radioisotope for intravascular brachytherapy. However, since there are some critical tissues in the vicinity of the heart like the breast and lymph nodes, it is necessary to perform a dosimetry calculation around the artery under radiotherapy to justify the treatment method. In this study, a 3-D dose distribution was obtained for the coronary vessel and its surrounding tissues for a standard 90Y stent in a MCNPX program. The results were compared with other investigations on restenosis prevention using 90Y-coated stents. The calculations represented a 28-day cumulative dose between 1230 cGy and 2400 cGy at 0.1 mm from the stent surface, while this quantity was about 23.8 cGy at 8.5 mm from the stent surface. An assessment of the dose equivalent and effective dose was also performed at r = 8.5 mm for the mentioned surrounding tissues which may be located in the area, based on the latest changes in ICRP recommendations. Additionally, the dose equivalent calculated within the treatment period for these organs was compared with published dosimetry data for 90Sr/90Y seed sources in order to evaluate radiation protection concerns about these two radiotherapy methods. It has been found that, depending on stent parameters, 90Y stent implantation might increase the unfavorable side effects for the patient, but to a much lesser degree than the other methods

Environmental dose rate assessment of ITER using the Monte Carlo method

Exposure to radiation is one of the main sources of risk to staff employed in reactor facilities. The staff of a tokamak is exposed to a wide range of neutrons and photons around the tokamak hall. The International Thermonuclear Experimental Reactor (ITER) is a nuclear fusion engineering project and the most advanced experimental tokamak in the world. From the radiobiological point of view, ITER dose rates assessment is particularly important. The aim of this study is the assessment of the amount of radiation in ITER during its normal operation in a radial direction from the plasma chamber to the tokamak hall. To achieve this goal, the ITER system and its components were simulated by the Monte Carlo method using the MCNPX 2.6.0 code. Furthermore, the equivalent dose rates of some radiosensitive organs of the human body were calculated by using the medical internal radiation dose phantom. Our study is based on the deuterium-tritium plasma burning by 14.1 MeV neutron production and also photon radiation due to neutron activation. As our results show, the total equivalent dose rate on the outside of the bioshield wall of the tokamak hall is about 1 mSv per year, which is less than the annual occupational dose rate limit during the normal operation of ITER. Also, equivalent dose rates of radiosensitive organs have shown that the maximum dose rate belongs to the kidney. The data may help calculate how long the staff can stay in such an environment, before the equivalent dose rates reach the whole-body dose limits

Test-retest reliability of transcarpal sensory NCV method for diagnosis of carpal tunnel syndrome

Background: Carpal Tunnel Syndrome (CTS) is the most frequent entrapment neuropathy affecting the upper extremity. There are a variety of electrodiagnostic methods available for documenting median neuropathy in CTS. In some studies, determining the sensory NCV across the palm-wrist segment has been introduced as the most sensitive diagnostic procedure for CTS. The aim of this study was to investigate the test-retest reliability of transcarpal median sensory NCV method for the diagnosis of CTS. Materials and Methods: Twenty-three patients with clinical symptoms of CTS were tested two times by two different practitioners in one session and again by the first practitioner after one week. Stimulation of the median nerve was performed in the wrist and palm, with a conduction distance maximum of 7 cm, reliabilities of median nerves sensory nerve action potential latencies with stimulation at wrist and palm (W-SNAP, P-SNAP) and its transcarpal NCV were assessed with intraclass correlation coefficient (ICC). Results: Comparison of the obtained values, which were done by two practitioners in one session showed ICC of W-SNAP latency, P-SNAP latency and transcarpal NCV of 0.93, 0.88 and 0.87, respectively and values that were done by one practitioner in two sessions with one-week interval showed ICC of 0.60, 0.50 and 0.47, respectively. Conclusion: Our findings suggest excellent interpractitioner test-retest reliability of transcarpal median sensory NCV method for diagnosing CTS

Automated Brain Tumor Segmentation on Multi-MR Sequences to Determine the Most Efficient Sequence using a Deep Learning Method

Brain tumor segmentation is an important step in the diagnosis and treatment planning of cancer patients. The procedure of manual brain tumor segmentation suffers from a long processing time. In this light, automatic brain tumor segmentation is highly appealing in the clinical routine. This study sets out to segment the tumors from brain MR images and to investigate the effectiveness/usefulness of the different MRI sequences for this purpose. Here, the MR images from the BRATS challenge were utilized. 310 patients with four different MRI sequences, including T1, T1ce, T2, and FLAIR were employed to train a ResNet deep CNN. Four separate models were trained with each of the input MR sequences to identify the best sequence for brain tumor segmentation. To assess the performance of these models, 60 patients (external dataset) were quantitatively evaluated. The quantitative results indicated that the FLAIR sequence is more reliable for automatic brain tumor segmentation than other sequences with an accuracy of 0.77±0.10 in terms of Dice compared to Dice indices of 0.73±0.12, 0.73±0.15, and 0.62±0.17 obtained from T1, T2, and T1ce sequences, respectively. Based on the results of this study, FLAIR is a more reliable sequence than other sequences for brain tumor segmentation

Preference Analysis of Formal and Informal Information Sources in Decision Making of Managers in SMEs

Objective: This survey aimed to determine the priorities of formal and informal sources of information for decision-making among managers of small and medium-sized enterprises (SMEs) in the Jey Industrial Zone (Shahrak-e Sanati-e Jey) in Isfahan, Iran. Materials and Methods: This quantitative research was done as a descriptive survey to determine the priorities of formal and informal sources of information for decision-making among managers of small and medium industrial enterprises. Jey Industrial Zone (Shahrak-e Sanati-e Jey) was selected for the study with 183 industrial enterprises, and 124 industrial enterprises were selected as the sample. Data was collected via a researcher-designed questionnaire. The validity of the data gathering tool was confirmed by the content validity method, and the reliability was determined using the Cronbach’s alpha internal consistency coefficient, with a result of 0.93. Data analysis was performed using SPSS software. Results: Technical information, information on the competition, and customer information are the types of information used in decision-making by managers in SMEs. Past documents archives, annual reports, and mission, vision, and goals of the industrial enterprises had the highest priority in internal and formal information sources and search tools, websites, web blogs, etc., and special books had the highest priority in external and formal sources. Knowledge and personal information (based on experience), experts, and colleagues had the highest priority in using informal sources. Conclusion: It can be concluded that managers in SMEs in Isfahan prefer internal formal information sources rather than external sources. Thus, there is a difference between the amount of internal and external sources usage. It is also revealed that informal information sources are used more than formal information sources in decision-making by managers in SMEs in Isfahan. Moreover, managers in middle-sized enterprises use informal information sources more than managers in micro and small enterprises

The role of central oxytocin in stress-induced cardioprotection in ischemic-reperfused heart model

Background and purpose: There is growing evidence that stress contributes to cardiovascular disease and triggers the release of oxytocin. Moreover previous studies confirmed oxytocin mimics the protection associated with ischemic preconditioning. The present study was aimed to assess the possible cardioprotective effects of the centrally released oxytocin in response to stress and intracerebroventricular (i.c.v.) administration of exogenous oxytocin in ischemic-reperfused isolated rat heart. Methods and subjects: Rats were divided in two main groups and all of them were subjected to i.c.v. infusion of vehicle or drugs: unstressed rats control: vehicle, oxytocin (OT; 100 ng/5 mu l), atosiban (ATO; 4.3 mu g/5 mu l) as oxytocin antagonist, ATO + OT] and stressed rats St: stress, OT + St, ATO + St]. After anesthesia, hearts were isolated and subjected to 30 min regional ischemia and 60 min reperfusion (IR). Acute stress protocol included swimming for 10 min before anesthesia. Myocardial function, infarct size, coronary flow, ventricular arrhythmia, and biochemical parameters such as creatine kinase and lactate dehydrogenase were measured. Ischemia-induced ventricular arrhythmias were counted during the occlusion period. Results: The plasma levels of oxytocin and corticosterone were significantly elevated by stress. Unexpectedly hearts of stressed rats showed a marked depression of IR injury compared to control group. I.c.v. infusion of oxytocin mimicked the cardioprotective effects of stress, yet did not elevate plasma oxytocin level. The protective effects of both stress and i.c.v. oxytocin were blocked by i.c.v. oxytocin antagonist. Conclusions: These findings suggest that i.c.v. infusion of exogenous oxytocin and centrally released endogenous oxytocin in response to stress could play a role in induction of a preconditioning effect in ischemic-reperfused rat heart via brain receptors. (C) 2012 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved