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In this study, we constructed an image reader system for two-dimensional radiation dosimetry based on radiophotoluminescence (RPL). The reader system mainly consists of a Peltier-cooled CMOS camera and an LED excitation source, as well as control units, and it offers an arbitrary excitation wavelength (e.g., 365, 405, 460, 530, and 630 nm) and a wide spectral detection range (200-1000 nm) to be used for a wide range of prototype image detectors having different spectral features. Using the developed system, we were able to successfully obtain X-ray projection images recorded on a commercial RPL detector [Ag-doped phosphate glass (Ag-PG) plate] as well as custom-made prototypes of flexible imaging plates (IPs). Furthermore, the reader system is applicable not only for RPL imaging but also for conventional optically stimulated luminescence (OSL) imaging, which was demonstrated by using a commercial IP for medical diagnosis. [ABSTRACT FROM AUTHOR]

Crucial questions in the debate on the origin of quintessential human behaviours are whether modern cognition and associated innovations are unique to our species and whether they emerged abruptly, gradually or as the result of a discontinuous process. Three scenarios have been proposed to account for the origin of cultural modernity. The first argues that modern cognition is unique to our species and the consequence of a genetic mutation that took place approximately 50 ka in Africa among already evolved anatomically modern humans. The second posits that cultural modernity emerged gradually in Africa starting at least 200 ka in concert with the origin of our species on that continent. The third states that innovations indicative of modern cognition are not restricted to our species and appear and disappear in Africa and Eurasia between 200 and 40 ka before becoming fully consolidated. We evaluate these scenarios in the light of new evidence from Africa, Asia and Europe and explore the mechanisms that may have led to modern cultures. Such reflections will demonstrate the need for further inquiry into the relationship between climate and demographic/cultural change in order to better understand the mechanisms of cultural transmission at work in Neanderthals and early Homo sapiens populations. [ABSTRACT FROM AUTHOR]

A new bubble counter has been developed based on the well-established approach of detecting vaporization events acoustically in superheated drop detectors (SDDs). This counter is called the Framework Scientific ABC 1260, and it represents a major improvement over prior versions of this technology. By utilizing advanced acoustic pattern recognition software, the bubble formation event can be differentiated from ambient background noise, as well as from other acoustic signatures. Additional structural design enhancements include a relocation of the electronic components to the bottom of the device; thus allowing for greater stability, easier access to vial SDDs without exposure to system electronics. Upgrades in the electronics permit an increase in the speed of bubble detection by almost 50%, compared with earlier versions of the counters. By positioning the vial on top of the device, temperature and sound insulation can be accommodated for extreme environments. Lead shells can also be utilized for an enhanced response to high-energy neutrons. [ABSTRACT FROM AUTHOR]

The superheated emulsion chamber (SEC) consists of superheated droplets of halocarbons in an aqueous gel. The gel resides in a pressure chamber. Brachytherapy sources can be implanted in the SEC for radiation dosimetry studies. Upon irradiation by ionizing radiation, the metastable droplets vaporize to form microbubbles. MRI can be used to determine the distribution of bubbles following irradiation of the SEC. In order to generate sufficient statistical accuracy in the determination of dose distributions around brachytherapy sources, it is necessary to use hundreds of irradiation cycles. Susceptibility-weighted images provide contrast between the gel and the vapor microbubbles. This article describes a 3D, blipped, double-sampled, segmented echo-planar imaging technique for rapidly imaging the SEC at 650 μm isotropic 3D resolution in about 2 min. This method was used with a pressure cycling SEC to acquire hundreds of images in several hours. Results are presented showing the 2D dose distribution generated by an 125I source as measured in the SEC using this new imaging method. Magn Reson Med 49:675–681, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

High-energy x-rays produced by radiotherapy accelerators operating at potentials above 10 MV may activate the air via (γ, n) reactions with both oxygen and nitrogen. While the activation products are relatively short-lived, personnel entering the accelerator room may inhale some radioactive air, which warrants internal dosimetry assessments. This work illustrates a method based on the use of ammonium nitrate solutions for the evaluation of photon-induced air activation and for the estimate of internal doses to radiotherapy personnel. Air activation and internal dosimetry assessments based on our method are presented for some widespread radiotherapy linear accelerator models. Our results indicate that the equivalent dose to the lungs of radiotherapy personnel is negligible for beam energies below 18 MeV. [ABSTRACT FROM AUTHOR]