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Better radiation protection at doctor‘s surgeries


In the past few years, there has been a change in medicine, industry and research – from continuous X-radiation to pulsed X-radiation. As PTB has discovered, many of the conventional electronic dosemeters therefore do not determine reliable values any more. Thus, in cooperation with the Siemens company, a new facility has been developed which will, for the first time, make the testing of dosemeters for measurements in pulsed radiation fields possible. Worldwide, it is the first facility of its kind.

With this facility, all physical parameters of the radiation pulse – tube current and tube voltage, pulse duration and repetition rate – can be adjusted almost independently of each other. Thereby, a special rotating anode X-ray tube is used. The tube current – and thus the ionising radiation – is switched on and off by a grid inside the tube. During that time, the high voltage is applied continuously, which is called “grid-controlled pulsing”. This has made it possible to generate radiation pulses with very short rise and fall times around 50 µs and pulse durations of only 0.2 ms up to continuous operation. The adjustable tube high voltage lies in the range from 40 kV to 125 kV; the tube current can be selected in the range from 0.5 mA to 800 mA. For electrical powers of up to 4 kW, continuous operation is possible; beyond that, only (short-term) pulsed operation is possible. At the maximum possible power of 80 kW, the maximum pulse duration is still 300 ms. The fact that the facility can generate continuous radiation is important for the metrological comparison with the conventional testing facilities and the primary standards of PTB. The pulse repetition rate can be up to 100 Hz.

To make sure that radiation protection can also be guaranteed in pulsed fields of ionising radiation, industry has already started to develop new electronic dosemeters, and PTB is involved in developing the respective standards within IEC and ISO.


Oliver Hupe
Department 6.3 Radiation Protection Dosimetry
Phone: +49 (0) 531 592-6310
E-Mail: oliver.hupe(at)ptb.de