Yes, you can use a couple different programs.
Alcohol 120% or CloneCD
I believe both have special profiles for ripping PlayStation One games. It won't really matter since you're using an emulator, but these programs both get the job done..
There is also Nero, but I think that saves in the proprietary NRG file format only so I wouldn't bother unless someone says it can save .ISO files. Alcohol can output MDF/MDS (a CD image and its cue sheet) and CloneCD saves CCD cue sheets, IMG for CD images, and SSD I think is the extension for subchannel data. Sot with CloneCD you usually get 3 files instead of 1 file (the CD image) or 2 files (the image and a cue sheet) with other programs.
In the end it doesn't matter. If your emulator supports the file format you end up with, you can change your config options to use an internal image mounter (if it has one) or install daemon-tools. DT emulates a CD/DVD-ROM drive. So you "mount" the CD Image you make of your game Disc(s) with Daemon Tools and then select the drive letter assigned to the virtual drive it creates and it reads it just like a CD/DVD-ROM, only its a hell of a lot faster.