Mask in AS3 cross object/multi object masking

I have a as3 class that loads a number of images from a given location, they are all loaded dynamically with imageloader. However I’m trying to make a Xray screen for all of them, so when I click and drag the Xray screen around, it will reveal the images loaded under each picture, creating a sort of Xray effect.

I tried using masks, however since the images are all loaded dynamically they are its own class with its own layers, I’m trying to make a mask that will work for all of them (I load 2 picture for each image, example car.jpg and carb.jpg, b.jpg being the inside image).

so I have my stage —> [MyXray Box, and my Images]

so my question is how can I use my Xray Box as a mask for all the Images?
Since Xray Box is a object of its own, it cannot use its own layers as the mask of another object. How do I do cross object masking?