While you could use a DVDRW disc and software that does packet writing most folk are very upset if this works 999 times out of 1000. DO NOT DO THIS!
Keep the photos safe on some HDD and USB stick and when you want them on DVD get out a DVDRW then with your recording software erase the DVDRW then make a data DVD with said software. Said software could be CDBURNERXP which is free, works with Windows XP, Vista, 7 and has tutorials so I don't write further about it.
I want to add pictures to dvd as I get them and do not know what dvd to buy.And the people at stores are stupid otherwise I would not have about 50 dvds that are useless to me.