The model EP917 is a 2nd generation, manually prototyped plaque (ca 2007) intended for small to medium size tumors (base ≤ 8x10 mm, height ≤ 6 mm tall).
The EP917 casting is similar to the prior USC#9 casting (ca 1993) that predates Eye Physics, but it is not exactly the same. The model 917 slots are a bit deeper (approx. 0.7 mm vs approx. 0.4 mm) and the seed coordinates are slightly different. Follow this link for EP917 vs USC#9 History.