Installing DOS doesn't do any good for 还原 your original image because GHOST will erase whatever you have on the disk or partition. The only thing that you will need is a GHOST bootable floppy disk. (you can create a GHOST bootable floppy disk from the GHOST application)
Here is a way how to reload GHOST image back to your machine:
Start your machine with this GHOST boot disk.
Then do the steps as 半个人 says, "按照图形界面:local-partition-from image,然后找到你的备份镜像来恢复"
Hope this help!