Hello
This require the customization of osirix plug-in for ROI. First of all, needs to check how the ROI is drawn over the DICOM image. If its already a plug in, may be the things are easier. Still, it will require the usage of VTK (visualization tool kit) to finish this task. As per my understanding, PHP is not at all required. We have experience in working with medical applications like PACS and Workstations. Cocoa + VTK + DCMTK (as the ROIs are usually kept in annotation sequence in exported DICOM files, the saving feature also will have to be modified, if my understanding is correct ) will be the technology stack to be applied here. I am not sure about how much time it will take. If you have more details, may be it will be easier to change. Please share any additional information you have. I can start working on this once you are ready to award me the project.
praveen at atomrise dot com