![]() ![]() While proton machines can be used for shoot-through techniques, the benefits of FLASH irradiation would have to be quite high to outweigh the conformality of a standard proton therapy delivery that leverages the sharp drop-off and low entry dose of the Bragg peak. For eventual applications to proton therapy, it is important to consider whether the effects observed in these studies can be combined with the superior conformality offered by the Bragg peak. Many industry leaders suggest that FLASH is a revolutionary discovery in the field of radiotherapy, expanding applications of radiotherapy to previously contraindicated cases. Results from these experiments support the claim that higher dose rate treatments with total treatment time under 1 second exhibit less normal tissue toxicity while maintaining tumor control typical of conventional treatments. Multiple groups have demonstrated this effect using photons, electrons, and protons. Better prediction of flash droughts is an active area of research.Research into the differential effect of high- and low-dose rates for radiotherapy has shown that higher dose rates (typically over 40 Gy/s) lead to improved normal tissue sparing. 2020).ĭespite the importance of prediction, scientists have found that flash droughts occur even when conditions just two months prior to the event appeared to be unfavorable for drought development, demonstrating that flash drought can occur even when there are no preceding signs that can be detected with known metrics ( Christian et al. 2019 ). They concluded that changes in evapotranspiration rates are a strong indicator of flash drought, and have developed a flash drought prediction tool to advance our ability to forecast these events ( Chen et al. Soil moisture was plentiful prior to the onset of drought, but decreased as evapotranspiration rates rose. In one study, researchers found that all flash droughts studied were preceded by sudden increases in evapotranspiration rates caused by changes in heat, wind, and radiation. Changes in evapotranspiration correspond with flash drought in the contiguous United States, indicating that it may be a primary mechanism involved in the sudden onset and intensification of drought conditions. Scientists have identified evapotranspiration and soil moisture as early warning indicators for the development of flash drought. The prediction of flash drought is critical to successfully mitigating and preventing damages whenever possible. For all climate regions, flash drought intensity tended to increase toward the beginning of the growing season and then decrease. The frequency of flash drought in the Southeast region generally peaked in May. In contrast, flash drought frequency across the central and parts of the eastern U.S. occurred more frequently in May and June, with the Northwest climate region seeing an additional peak at the end of the growing season. One study found that between 1979–2016, flash droughts in the western U.S. In contrast with conventional drought-which may occur throughout the year at any location-flash drought typically occurs during warm seasons in the central United States. Geographic differences and climate patterns also impact the development of flash drought. These sometime-rapid changes can quickly raise evapotranspiration rates and remove available water from the landscape. Unlike slow-evolving drought, which is caused by a decline in precipitation, flash drought occurs when low precipitation is accompanied by abnormally high temperatures (e.g., heat waves), high winds, and/or changes in radiation.
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