PubMed · 7454764
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
P J Rudd. 1980. An automatic timer control unit for the Farmer dosemeter type 2501/3.. https://doi.org/10.1088/0031-9155%2F25%2F4%2F013
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
When the absorbed dose conversion factor of the x-rays is looked for, generally it is being done how to measure the effective energy (keV) from the half-value layer. But, spectrum measurement is necessary to evaluate quality of x-ray precisely. So, 2.94% of the maximum differences were in the water, soft tissue, and 20.93% of the maximum differences were in search of absorbed dose conversion factor due to the half-value layer and the spectrum as a compared result by cortical bone. And, when a x-ray tube voltage rose, this difference showed a tendency of spreading out. A cause was because the rates of the photon of the higher energy than the energy measured with effective energy increased by a x-ray tube voltage's rising. The ratio of the mass energy absorption coefficient which faces air like cortical bone should be careful because an error by the absorbed dose conversion factor grows big when a absorbed dose conversion factor is measured by the big absorption medium, though it is as the difference in absorbed dose conversion factor is compared with an error by the dosimeter and there is no problem in the water, soft tissue.
This paper outlines how objective measurements of both image quality, in terms of signal-to-noise ratio, and effective dose may be used as tools to find the optimum kVp range for a digital chest radiography system. Measurements were made with Thoravision, an amorphous selenium-based digital chest X-ray system. The entrance surface dose and the effective dose to an anthropomorphic chest phantom were determined demonstrating how effective dose is related to beam quality. The image quality was measured using detective quantum efficiency, threshold contrast and a radiologist preference trial involving 100 patients. The results show that, despite the fact that the entrance surface dose decreases as the kVp increases, the effective dose, a better measure of the risk, reaches a minimum value between 90 and 110 kVp; however, the image quality decreases as the kVp increases. In this study the optimum kVp for chest radiography, using a selenium-based radiography system, is in the range 90-110 kVp. This is contrary to the 120- to 150-kVp range that is commonly used. Also, this study shows how objective measurements can be used to optimise radiographic technique without prolonged patient trials.
The concentrations of 222Rn (radon) and its progeny with surrounding environmental gamma-dose rates were measured simultaneously inside and outside of buildings at 10 locations around Taipei and Hualien in Taiwan. For summer radon in Taiwan, indoor concentrations were estimated to be about 20 Bq m(-3) with about 90 nSv h- of environmental gamma, and outdoors, about 10 Bq m(-3) with about 70 nSv h(-1). The equilibrium factors were calculated to be 0.2-0.3 indoors and 0.3-0.4 outdoors. Indoor radon concentration had a weak positive correlation with gamma-dose rate. Since there is a possibility that high radon concentrations exist indoors during the cool season in Taiwan because of extremely low ventilation rates in the dwellings, a winter survey in January through February will be needed for future estimation of the annual effective dose.