Source:http://linkedlifedata.com/resource/umls/id/C3203759
UMD: Measuring instruments designed primarily to measure very small (in the order of femto coulombs) electric charge values; the instruments are frequently based on the accurate measurement of voltages. These devices typically consist of electronic instruments including a high-input impedance solid state amplifier (e.g., such as field-effect transistors, FETs), voltage supplies, and a display to show charge, voltage, and current values; they may also include external connections to attach ionization chambers to perform radiation measurements. Electrometers are frequently intended for radiation therapy dosimetry; they can measure charge from electrons, x-rays and gamma rays emitted by linear accelerators, cobalt 60 units, and other radiation sources.