To make everybody aware of a hazard in any area where there exists a source of radiation and one can get exposed to it or may get contaminated and should take precautionary measures to avoid it, generally the trefoil ionizing radiation symbols are used (Fig. 1, 2). These are magenta or black propellers on yellow background. For radiation hazard associated with an X-ray machine the symbol used is given in Fig. 3. For internal components inside a device/machine that contains radiation hazard the symbol recommended by ISO and IAEA is given in Fig. 4. The chart that is supposed be posted on AERB approved X-ray facility is given in Fig. 5.

Fig. 1: Trefoil radiation Symbol 1 for radiation hazard	Fig. 2: Trefoil radiation Symbol 2 for radiation hazard
Fig. 3: Radiation Symbol for X-Ray radiation hazard	Fig. 4. Radiation symbol for sealed sources

For inner circle of radius R, the inside radius of the blades is 1.5R and the outer radius of the blades is 5R. The blades are separated by 60°.

This is the mandatory symbol that has to be posted in and around a facility using an X-ray machine.

Hazard Symbol of radiation source, associated hazard and precaution on a component containing sealed source inside a machine/device

For details please see IAEA Page