Well yes, but I wanted low color count.

The challenge limit is 19 colors?

Ok, tried to make bg more contrast to foreground.
It was a bit hard with 6 colors.
  And this is more zombie green than radioactive glow.

It seems better now, you can maybe change the bg colors in order to bring the portrait forward.

I'm bad with colors.
Tried to make it less greenish, what do you think?
 

I like the pixelling but not sure about the highly saturated green colors. If you wanted a "radiation glow" effect, you should choose more desaturated colors with few high saturation green beams or glowing places.

Or at least address the green background, which makes the piece even more monotonous.