public function buildImgs(imgs:Array):void{

for(var i:int=0;i<imgs.length;i++){

        var loader:Loader = new Loader();

        loader.contentLoaderInfo.addEventListener(Event.INIT, initImg);

             loader.load(new URLRequest("a/1/"+imgs[i]+".png"));

        }

}

public function initImg(event:Event):void{

var loader:Loader = Loader(event.target.loader);

var info:LoaderInfo = LoaderInfo(loader.contentLoaderInfo);

loader.x=50*i;

...

box.addChild(loader);

}