The first non-destructive testing method for internal defects was implemented in the beginning with X-ray films after the discovery of X-rays by Wilhelm Conrad Röntgen in 1895. With many standards and testing instructions, this technology is very well established and safe. This is probably why film consumption has remained stable at a high level for many years.
The world is becoming increasingly "digital," and with a film digitizer, this established technology can be transferred to the digital age — but the demands on the digital images are very high, simply because the film contains an extremely large amount of information. A normal camera or smartphone can't be used for this task.