Many healthcare organizations are already using Microsoft Office 365 Business Essentials, including exchange online for email. Office 365 Business Essentials includes OneDrive Online, which is a convenient platform for storing and sharing files.
Microsoft supports HIPAA-compliance and many of its cloud services, including OneDrive, can be used without violating HIPAA Rules, however you will need to obtain "Business Associate Agreement (BAA). Microsoft offers a BAA through the Online Services Terms. If you are using Microsoft Office 365, you might already have one. Given Microsoft offers a HIPAA-compliant secure storage option, it means OneDrive, in conjunction with PicSafe, can use used to help you comply with HIPAA and HITECH. Please see the Microsoft and HIPAA and the HITECH Act page on their website for more detailed information.
The "Office 365 Business Essentials" plan, may be all you need. That gives you 1TB of storage which should be enough for roughly 200,000 photos. If you require more storage space, you can upgrade to various paid plans.