new method to monitor the surface contamination on some devices in hot cells is presented. According to the straight propagation of γ rays

their interaction with materials

and the pinhole imaging principle

a pinhole camera

made of 238U material

was developed. With this camera

both contaminations on the device and the device itself can be imaged. Overlapping of the two photos by a computer will give a new picture

which can tell both distribution and intensity of the contaminations. This method ensures a more direct and clear γ-contamination monitoring

and a less exposure dose to the monitoring workers.