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Geiger counter [keywords]
- Method to remove the effect of ambient temperature on radiometric calibration. [Journal Article]
- Appl Opt 2014 Sep 20; 53(27):6274-9.
High precision radiometric calibration is essential for infrared imaging systems, especially in scientific applications where an accurate quantitative analysis is required. Nevertheless, calibration and radiometry are usually not simultaneously performed. Hence the discrepancy of ambient temperature between calibration and actual measurement can generate significant measurement errors unless the calibration results have been properly corrected. To overcome the restriction, we studied the effect of ambient temperature on radiometric calibration, then derived the relationship between calibration results and ambient temperature considering the integration time. A novel method compensating for the impact of ambient temperature on the calibration of a cooled infrared system is proposed. Several experiments are performed, and the results indicate that the proposed method can not only ensure the accuracy of calibration but achieve calibration results under any ambient temperature and arbitrary integration time.
- Impacts of dichroic prism coatings on radiometry of the airborne imaging spectrometer APEX. [Journal Article]
- Appl Opt 2014 Aug 20; 53(24):5344-52.
The generation of well-calibrated radiometric measurements from imaging spectrometer data requires careful consideration of all influencing factors, as well as an instrument calibration based on a detailed sensor model. Deviations of ambient parameters (i.e., pressure, humidity, temperature) from standard laboratory conditions during airborne operations can lead to biases that should be accounted for and properly compensated by using dedicated instrument models. This study introduces a model for the airborne imaging spectrometer airborne prism experiment (APEX), describing the impact of spectral shifts as well as polarization effects on the radiometric system response due to changing ambient parameters. Key issues are related to changing properties of the dichroic coating applied to the dispersing elements within the optical path. We present a model based on discrete numerical simulations. With the improved modeling approach, we predict radiometric biases with an root mean square error (RMSE) below 1%, leading to a substantial improvement of radiometric stability and predictability of system behavior.
- [Peculiarities of serum lipid profile in patients with thyroid pathology professionally exposed to low-dose radiation]. [English Abstract, Journal Article]
- Klin Med (Mosk) 2014; 92(2):38-43.
The study included 90 patients with coronary heart disease (CHD) with NYHA FC I-II cardiac insufficiency professionally exposed to ionizing radiation (IR). 30 patients had isolated CHD, 30 presented with CHD and concomitant euthyroid autoimmune thyroiditis (ALT) and 30 with hypothyroid AIT. The control group consisted of 30 patients with the same pathologies unexposed to IR. Peculiarities of serum lipid profile in the patients of all groups were investigated. It was shown that professional exposure to low-dose radiation had no appreciable effect on the lipid spectrum in professionals with CHD even if it combines with AIT without hormonal disorders (euthyroidism). The only clinically significant effect of IR was hypothyroidism in patients with CDH and AIT. Even then, marked atherogenic changes were diagnosed only in those cases where adequate replacement therapy failed to totally compensate for hormonal insufficiency.
- [Anthropometric differentiation of effects of radiofrequency electromagnetic fields of frequency 100 MHz on workers]. [English Abstract, Journal Article]
- Med Pr 2014; 65(3):351-60.
Thermal effects of radiofrequency electromagnetic fields (REMF) exposure of humans may be assessed by calculations of the parameter recognized as SAR (specific energy absorption rate) in virtual human body models, which actually do not represent anthropometric properties of the entire population. Therefore, it is important to determine the relations between SAR values and anthropometric parameters that enable individualization of SAR estimation independently of body properties of a given person.The analysis concerned 48 exposure scenarios of 4 virtual body models (male and female) to vertically or horizontally polarized REMF of 27 MHz or 100 MHz frequency of various directions of propagation.In the subgroup of results 100 MHz/vertical polarization statistically significant (strong; p < 0.05) correlations were identified between SAR averaged in the whole body and height, mass, BMI, circumference of chest, waist, neck and frontal cross-section area, and between local SAR in head and neck and the height, mass, circumference of chest waist or neck and frontal cross-section area. Identified relations and SAR in the Gustav model were used to estimate the variety of SAR in Polish population of adults (5-95. percentile of female and male): +/- 30% for SAR averaged in the whole body, +/- 50% for localized SAR.It was demonstrated that in the preliminary classified type of assessed REMF exposure (e.g., in terms of field polarization and frequency) it is possible to identify statistical relations between various SAR parameters and anthropometric properties of the exposed body. Related quantities can be used for individualized assessment of worker's electromagnetic hazards.
- [Effect of extremely low frequency magnetic field on glutathione in rat muscles]. [English Abstract, Journal Article]
- Med Pr 2014; 65(3):343-9.
Free radicals (FR) are atoms, molecules or their fragments. Their excess leads to the development of oxidizing stress, the cause of many neoplastic, neurodegenerative and inflammatory diseases, and aging of the organism. Industrial pollution, tobacco smoke, ionizing radiation, ultrasound and magnetic field are the major FR exogenous sources. The low frequency magnetic field is still more commonly applied in the physical therapy. The aim of the presented study was to evaluate the effect of extremely low frequency magnetic field used in the magnetotherapy on the level of total glutathione, oxidized and reduced, and the redox state of the skeletal muscle cells, depending on the duration of exposure to magnetic field.The male rats, weight of 280-300 g, were randomly devided into 3 experimental groups: controls (group I) and treatment groups exposed to extremely low frequency magnetic field (ELF-MF) (group II exposed to 40 Hz, 7 mT for 0.5 h/day for 14 days and group III exposed to 40 Hz, 7 mT for 1 h/day for 14 days). Control rats were kept in a separate room not exposed to extremely low frequency magnetic field. Immediately after the last exposure, part of muscles was taken under pentobarbital anesthesia. Total glutathione, oxidized and reduced, and the redox state in the muscle tissue of animals were determined after exposure to magnetic fields.Exposure to low magnetic field: 40 Hz, 7 mT for 30 min/day and 60 min/day for 2 weeks significantly increased the total glutathione levels in the skeletal muscle compared to the control group (p < 0.001).Exposure to magnetic fields used in the magnetic therapy plays an important role in the development of adaptive mechanisms responsible for maintaining the oxidation-reduction balance in the body and depends on exposure duration.
- Ultrasonography versus computed tomography for suspected nephrolithiasis. [Journal Article, Research Support, U.S. Gov't, P.H.S.]
- N Engl J Med 2014 Sep 18; 371(12):1100-10.
There is a lack of consensus about whether the initial imaging method for patients with suspected nephrolithiasis should be computed tomography (CT) or ultrasonography.In this multicenter, pragmatic, comparative effectiveness trial, we randomly assigned patients 18 to 76 years of age who presented to the emergency department with suspected nephrolithiasis to undergo initial diagnostic ultrasonography performed by an emergency physician (point-of-care ultrasonography), ultrasonography performed by a radiologist (radiology ultrasonography), or abdominal CT. Subsequent management, including additional imaging, was at the discretion of the physician. We compared the three groups with respect to the 30-day incidence of high-risk diagnoses with complications that could be related to missed or delayed diagnosis and the 6-month cumulative radiation exposure. Secondary outcomes were serious adverse events, related serious adverse events (deemed attributable to study participation), pain (assessed on an 11-point visual-analogue scale, with higher scores indicating more severe pain), return emergency department visits, hospitalizations, and diagnostic accuracy.A total of 2759 patients underwent randomization: 908 to point-of-care ultrasonography, 893 to radiology ultrasonography, and 958 to CT. The incidence of high-risk diagnoses with complications in the first 30 days was low (0.4%) and did not vary according to imaging method. The mean 6-month cumulative radiation exposure was significantly lower in the ultrasonography groups than in the CT group (P<0.001). Serious adverse events occurred in 12.4% of the patients assigned to point-of-care ultrasonography, 10.8% of those assigned to radiology ultrasonography, and 11.2% of those assigned to CT (P=0.50). Related adverse events were infrequent (incidence, 0.4%) and similar across groups. By 7 days, the average pain score was 2.0 in each group (P=0.84). Return emergency department visits, hospitalizations, and diagnostic accuracy did not differ significantly among the groups.Initial ultrasonography was associated with lower cumulative radiation exposure than initial CT, without significant differences in high-risk diagnoses with complications, serious adverse events, pain scores, return emergency department visits, or hospitalizations. (Funded by the Agency for Healthcare Research and Quality.).
- In vitro comparison between the image obtained using PSP plates and Kodak E-speed films. [Comparative Study, In Vitro, Journal Article]
- Refuat Hapeh Vehashinayim 2014 Jul; 31(3):33-8, 61.
The aim of this study was to compare the intra-oral radiographic images obtained by a PSP digital radiography system ("Orex", Israel) with that obtained using Kodak Ultra speed films in terms of image quality, radiation dosage and diagnostic value.The physical measurement of image quality was conducted with an aluminum step-wedge. Radiation dosage was measured with a dosimeter. Fog and base levels were measured by developing unexposed films and scanning unexposed PSP plates. The in vitro model included preparation and radiographic evaluation of approximal artificial lesions in premolars and molars in depths ranging from 0.25 mm to 1.00 mm. Radiographs were evaluated for the existence of a lesion and its size by 8 experienced clinicians.Relative contrast was similar in both methods. The resolving power of the digital system was lower than that of the E-speed film. As for the subjective evaluation of artificial lesions, there was no significant difference between the two methods excluding those tooth images without lesions, where the analog method was found to be more accurate.The PSP system ("Orex") provides good image quality and diagnostic information with reduced exposure when compared with E-speed film.
- [Lung cancer screening in Japan -present and future]. [Journal Article]
- Gan To Kagaku Ryoho 2014 Aug; 41(8):955-9.
- The effect of interincisal opening, cavity location and operator experience on the energy delivered by a light-curing unit to a simulated dental restoration. [Comparative Study, Journal Article]
- Prim Dent J 2014 May; 3(2):26-31.
Curing of resin-based composites depends on the delivery of adequate total energy, which may be operator dependent. Aim To determine the effect of interincisal opening, cavity location and operator experience on the total energy delivered to simulated cavity preparation sites.Three cohorts were included: junior dental nurses, senior dental nurses and qualified dentists (N=5, each cohort). Each operator (participant) followed the same procedure and light-cured two simulated restorations in a MARC patient simulator using a Demi light-curing unit for 20 seconds in each of the following situations: left upper second molar (UL7), interincisal opening at both 25 mm and 45 mm; upper central incisor (UR1), interincisal opening at 45mm. The light energy delivered by each operator in each situation was recorded. Five readings for each operator were taken at each interincisal distance. Statistical comparisons of delivered energy (J/cm2) between interincisal openings, location and groups in the total energy delivered were performed using the Kruskal-Wallis nonparametric test: alpha = 0.05.Less total energy was delivered to the posterior cavity at 25mm (12.0 +/- 5.3 J/cm2) than at 45mm (16.9 +/- 5.6 J/cm2) by all operators (P < 0.05). At 45 mm, less total energy was delivered to the posterior cavity compared to the anterior cavity (25.1 +/- 7.4 J/cm2; P < 0.05). There was no statistically significant difference between junior nurses and qualified dentists (P > 0.05) but there was a significant difference in the total energy delivered between senior nurses (20.1 +/- 7.8 J/cm2) and junior nurses (17.5 +/- 7.6 J/cm2) and between senior nurses and qualified dentists (16.6 +/- 8.7 J/cm2) (P < 0.05).Interincisal mouth opening, location of the cavity and operator experience affected the total energy delivered to cavities in a simulated clinical environment.