checking integrity of already written CD/DVD

[Angelin Lalev <lalev.angelin@gmail.com>]

Greetings,

I'm about to lend my entire DVD set with Debian 5.0 to a friend. I
have no doubt in my friend, but this occasion awakened the curious
person in me and here is the question:

Is there a way to check that the DVD I give to somebody is the same
that the DVD I'll get later?

More complex:

Is there a way to check a written DVD against the checksum of the iso
image written on it?

(For example to check that Debian 5.0 Lenny Official i386 Binary-1 DVD
I got from someone has written on it
exactly the .iso file from debian.org)