Automatic exposure control

The KS-87B camera is in the Department of Defense inventory. It is a pulse-operated frame camera with a high-speed focal plane shutter, integral automatic exposure control and data recording, and forward... 

If automatic exposure controls become faulty or technique begins to slip, it is easy for a high radiation dose to be missed as there is little visible change to the image. The darkness or lightness of an image that traditionally was the guide to exposure is of no... 

C-arm CT systems with automatic exposure control (AEG) adjust X-ray exposure parameters such that the detector entrance dose remains constant. Detector entrance dose is the X-ray dose measured behind the antiscatter grid. System dose is the detector entrance dose evaluated at a reference detector zoom format. System dose is an important set-up parameter for C-arm CT imaging protocols on Artis zee systems (Siemens AG, Healthcare Sector, Forchheim, Germany). Due to internal adjustments, the detector entrance dose for C-arm CT is about half the system dose. 

McCollough CH (2005) Automatic exposure control in CT Are we done yet Radiology 237 755-756 Meyer B, Frericks B, Albrecht T, etal. (2007) Contrast-enhanced abdominal angiographic CT for intra-abdominal tirnior embolization A new tool for vessel and soft tissue visualization. Cardiovasc Intervent Radiol 30 743-749... 

Automatic exposure control 1/8 ratio short/long... 

Splash protection. Splash protection includes enclosure guarding with chemical-resistant panels, automatic feed and ejection systems to minimize the operator s exposure to the chemicals, use of proper personal protective equipment, and automatic shutoff controls at a convenient location. 

The programmable, automatic irradiance control system allows the operator to choose a higher than standard level of irradiance for UV exposure tests. For many materials, this results in faster degradation and therefore shorter test times. ... 

Humidity can be a problem. Whereas it was shown (284) that 33% RH was best for spore inactivation, and that at least 30% RH was needed for effective sterilisation (285), dried spores are difficult to kill, and the spore substrate material and wrappings compete with the spore for the available moisture (286). Therefore, the relative humidity is adjusted to 50—70% to provide sufficient moisture for the spores to equiUbrate. The exposure time depends upon the gas mixture, the concentration of ethylene oxide, the load to be sterilised, the level of contamination, and the spore reduction assurance requited. It may be anywhere from 4—24 hours. In a mn, cycles of pre-conditioning and humidification, gassing, exposure, evacuation, and air washing (Fig. 9) are automatically controlled. 

Provision and use of appropriate health surveillance, e.g. for signs of dermatitis, asthma, effects of specific solvent exposures. Full use of any spray booth, enclosure, exhaust ventilation or dilution systems, and automatic handling equipment. (The efficiency of all local exhaust ventilation and other control systems should be maintained, and checked by testing.) Where appropriate, atmospheric monitoring of airborne pollution levels. 

Figure 4.5 Influence of oxidant stress on action potentials recorded In an isolated rabbit ventricular myocyte, (a) Control action potential, (b) Action potential recorded 3 min after exposure to oxidant stress induced by the photoactivation of rose bengal (50 nu). (c) Spontaneous and repetitive action potential discharges induced 6.5 min after exposure to rose bengal. Action potentials were recorded via a 2.5 MQ suction electrode and a current-clamp amplifier. The cell was stimulated at 0.1 Hz with a 2 ms suprathreshold current pulse and, when the cell showed automaticity (after 6 min), stimulation was stopped. Redrawn from Matsuura and Shattock (1991b).

Light Exposures. Silk fabric samples, 0.25 m x 0.17 m, were mounted in Atlas Electric Devices aluminum sample holders according to AATCC Test Method 16E-1982 (7). An Atlas Ci-35 Weather-Ometer xenon-arc was used on continuous light cycle. Exposures were conducted at an irradiance of 0.35 W/m2 measured at 340 nm and the irradiance was monitored and controlled automatically. Borosilicate inner and outer filters were used to simulate the solar spectrum. The relative humidity was maintained at 65% and the black panel temperature was 50°C. The actual fabric temperature during the irradiation was measured, using small thermocouples threaded into the fabric, and was found to be 35 C. Control samples for these tests were kept in the dark at 35°C and 65% RH for the same time period as the illuminated samples. 

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