Where do you buy CDs that hold 10GB?
A CD holds 700 MB of data. A DVD holds 4.7GB of data.
The image file is compressed. usually 2 to 1 at standard settings. So 80GB of data will create about a 40GB image.
Because the system image is just one big compressed file it is highly unlikely that the image would be infected by a virus or malware (unless you make a image that contains one). And you can scan your external drive with AV before you restored an image.
But yes, your image on DVDs would be "safer".
But way more inconvenient.
And there can be issues with restoring an image that spans multiple DVDs. The more disks, the greater the possibility of error.
EDIT: And please don't cross post!