Calling Windows DLL Files

I don't know if this is possible, but I figured there is a small limitation on php.... The scenario... I have a client that wants his application revamped from MS Access to mySQL and PHP. Now, he is a doctor in an office and he scans patients information in. He wants the ability to click a button on the GUI which launches the scan program(TWAIN32.DLL I think) then automatically saving the scanned file in the designated folder or location. I informed him its the scanning applications responsibility to scan and automatically save it, so in order to designate the location I need to either: 1. Find a program that does that, 2. Write a new scanning application. I think this guy is starting to want too much, but if it is possible I would like to give it a whirl. Is this possible?