Flash :: Manage Multiple Sizes (dimensions) Of Bitmaps?

I have a custom Image class that I am using to store individual image information for a gallery application:

package mtm.test
{
public class Image extends Object
{

[Code]....

This is how I would implement the above:

var image:Image = new Image();
//I would be loading external bitmaps but for the example I'll just create new ones:
image[BitmapThumbnail] = new BitmapThumbnail(new BitmapData(65,65,false,0x000000));

[Code]....

Is there a simpler way to do this? I feel that there is a lot of repeated code within the BitmapType sub-classes.

At the least, this helps to avoid a bunch of for loops trying to find the requested size, and it seems portable to situations where more or less sizes of Bitmaps are required.