23 -- Dental X-rays and Lead Aprons

In the 1950s, it was decided, absent data, that low dose radiation was as bad as high dose and so no dose would be tolerated. This was called the Linear No-Threshold (LNT) dose hypothesis. Today this is being overturned in medicine and eventually in dentistry. https://www.forbes.com/sites/jamesconca/2020/01/28/ditch-that-lead-apron-in-the-x-ray-room/#227a1e413bd5 https://www.nytimes.com/2020/01/14/well/live/radiation-exposure-x-rays-scans-lead-apron.html https://www.sciencedirect.com/science/article/abs/pii/S0764446999800444