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Measurement Techniques
Published in Marvin C. Ziskin, Peter A. Lewin, Ultrasonic Exposimetry, 2020
Marvin C. Ziskin, Peter A. Lewin
In most practical applications, the target is chosen as large as possible and the aim is to determine the total, time-average ultrasonic power. The type of instrument used to accomplish this task is generally referred to as the radiation force balance, although gravimetric balances in the strict sense constitute only one group of these devices. The use of a radiation force balance will be dealt with in detail here. Another type of instrument is the suspended sphere radiometer. Here, a small sphere is used as the target and the aim is to determine the local values of the time-average ultrasonic intensity. This is beyond the scope of the present text. The sphere radiometer suffers from its limited sensitivity1 and from the complicated force/intensity relation, strongly dependent on frequency and on the individual properties of the sphere material.2
Radiation Sources and Interaction with Skin
Published in Henry W. Lim, Herbert Hönigsmann, John L. M. Hawk, Photodermatology, 2007
In the clinic, the irradiance is measured with a radiometer. For a specified delivered radiation dose, the duration of exposure can be calculated from the above formula. Each radiation source requires its own specific radiometer, since the spectral sensitivity should match the source’s spectral output.
Animal Models for Phototoxicity Testing
Published in Francis N. Marzulli, Howard I. Maibach, Dermatotoxicology Methods: The Laboratory Worker’s Vade Mecum, 2019
Lark A. Lambert, Wayne G. Warner, Andrija Kornhauser
Regular measurement of the radiation emitted from irradiation sources is essential for reliable phototoxicity testing. Instruments for measuring optical radiation are of two types: spectroradio-meters and broadband detectors. Spectroradiometers allow measurement of spectral intensity from a radiation source with a bandpass, or increment, of 1 or 2 nm. Standard lamps, such as those obtained from the National Institute of Standards and Technology in the United States, are used to calibrate spectroradiometers before measurements of sources used in phototoxicological studies (Landry and Andersen, 1982). Broadband radiometers, which display radiation intensity over an entire spectral region rather than small nanometer intervals, are the more frequently used instruments in measurements of source radiation. As with spectroradiometers, calibration of broadband radiometers is critical to their proper use. Since spectral power distributions differ between radiation sources used in phototoxicity testing, and detector response varies with the wavelength of radiation measured, broadband radiometers must be calibrated separately for each source to be measured (Levin, 1986). For accurate measurement of radiation-source emission, adequate time must be allowed for the source to stabilize. Diffey (1988) showed that the time required for different sources to warm up can vary significantly. Finally, the intensity of radiation can vary significantly throughout the field illuminated by a radiation source (Hitchins et al., 1986). It is prudent, therefore, to make multiple measurements over the area being exposed in a phototoxicity test.
Imaging-based internal body temperature measurements: The journal Temperature toolbox
Published in Temperature, 2020
Juho Raiko, Kalle Koskensalo, Teija Sainio
In 1974, Edrich et al. [100] and Enander et al. [101] suggested that internal body temperatures could be measured by a radiometer measuring millimeter wavelength thermal noise signals. A microwave radiometer is a passive receiver measuring the intensity of thermally generated microwave electromagnetic noise by all substances with a temperature above 0 K. The intensity of the microwave noise signal correlates directly with the absolute temperature of the target tissue [102]. The antenna of the radiometer device is placed on the surface of the body above the target tissue to perform the measurement of the deep temperature (see Figure 8). The microwave radiation received by the antenna is then converted to absolute temperature based on the weighted average of the radiation pattern of the target material [103]. The advantage of microwaves over infrared radiation is the higher tissue penetration of radio waves with high wavelength: while infrared has poor penetration and can be used to measure only the surface temperature, radio waves penetrate several centimeters of subcutaneous tissue and can be used to measure internal tissue temperature. The power P of the radio length radiation of the examined tissue can be described as:
Quality planning and control strategy for AQT90 flex Radiometer® in point of care testing
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2020
Claudio Ilardo, Cecile Reynaud, Regine Bonneton, Joel Barthes
Seven parameters used in the AQT90 flex Radiometer® (Bronshoj, Denmark) were studied: Troponin, NT-proBN, Myoglobin, HCG, Procalcitonin, CRP and D-Dimer. The analytical performance was evaluated according to the technical validation protocol in accordance with the requirements ISO 15189:2012 [3]. Imprecisions was estimated in each event by two level quality controls of the company Radiometer®. External quality assessments provided by Probioqual ® (Lyon, France) and Bio-Rad ® (Hercules, USA) were regularly evaluated for each parameter. For the calculation of imprecision, the IQC data were collected for two months with thirty-five results per parameter. For bias estimation, external quality control results were collected over a year, and the number of results varied between 8 and 12 results depending on the external programs.
Efficacy of single phototherapy with low-cost reflective sheets versus single phototherapy alone in mild-to-moderate unconjugated hyperbilirubinaemia in full-term neonates
Published in Paediatrics and International Child Health, 2021
Amira M. Sabry, Mortada H. F. El- Shabrawi, Abdelrahman A. Abdelrazek, Mahmoud F. Ali
Several factors affect the efficacy of phototherapy such as the spectral qualities, irradiance of the light source, exposed patient surface area and distance from the light source [4]. Conventional phototherapy units provide minimal levels of effective phototherapy (about 6–12 μw/cm2/nm) [5], while intensive phototherapy gives greater irradiance in the blue-green spectrum (wavelength approximately 430–490 nm) of at least 30 μw/cm2/nm. Radiometers (bilimeters) are used to measure the spectral irradiance [6].