九九九在线_国产精品无码久久久久一区二区_秋霞午夜鲁丝一区二区老狼_久草91_久热99_精品福利一区二区三区_爱爱福利社_一级α片免费看刺激高潮视频_九九精品网_激烈娇喘叫1v1高h糙汉_av天天干_操操操av_日韩视频一区二区三区_欧美黑人xxx_欧美性猛交xxxx乱大交退制版

Medical radioactivity meter is an instrument for measuring radioactive decay rate. Radioactive decay rate was once called radioactivity and radioactivity intensity. In 1962, the International Commission on Radiological Units recommended the use of radioactivity. In 1975, the international metrology conference stipulated that the standard unit of activity is "BQ" (BQ), one decay per second is equal to one Becquerel. "Curie" (CI) is still a temporary unit. 1Ci=3.7×1010Bq。


Application of medical radioactivity meter


The activity meter is widely used in hospitals, radioactive pharmaceutical plants, nuclear power plants, radioactive source manufacturers, scientific research departments and radioactive measurement and testing departments. With the development of nuclear medicine, new isotope diagnosis and treatment drugs are emerging, and the application of new isotopes is increasing. It is necessary for the long-term development of the hospital to have a medical radioactivity meter with good performance and can measure various nuclides. It is also essential for the activity detection and quality control before medication.


The basic component of standard activity meter is 4 π γ high pressure well type ionization chamber. When the radioactive source is put into the well, the gamma ray is emitted to all directions. The borehole wall is used as the receiving window, and the solid angle is close to 4 π. Therefore, the detection efficiency is very high, and the detection efficiency depends on the absorption of the borehole wall. The lower the energy, the stronger the absorption. For example, the main gamma ray energy of 125I is 27.5kev, so it is difficult to penetrate stainless steel shaft wall, only aluminum shaft wall can be measured. It is internationally recognized that aluminum is the best material for shaft lining. However, aluminum welding is a difficult problem, which has not been solved in China for a long time. This problem has been overcome by our company.


Another characteristic of medical radioactivity meter is that it can measure many nuclides and has good stability. Especially for low activity measurement, many types of activity meters at home and abroad can not give stable measurement values for nuclides < 10 μ Ci, and the error of our products can be less than or equal to 5%.