Persistent luminescent materials for medical imaging

Persistent luminescent materials or glow-in-the-dark compounds have been known for centuries [1], but due to their limited performance in terms of total light output, they were never used for large scale applications. It is only since 1996 [2], when SrAl2O4:Eu,Dy was introduced as a new persistent phosphor, that a leap forward in both brightness and decay time was achieved. This paper has initiated substantial research, which has led to an entire family of materials, showing an appreciable afterglow for more than 24 hours [3,4].