You'll need to restructure your database or design a different layout to achieve the same purpose. Here's one way you might achieve this:
Define a related table, Regions with at least these two fields:
Region (Text, with values North, West, South, etc.)
Relate it to your original table, (I'll call it Doctors) like this:
Doctors::MD_ID = Regions::MD_ID (Enable allow creation of records via this relationship for Regions, but NOT for Doctors.)
Doctors::MD_ID should be an auto-entered serial number.
Place a portal to Regions on your layout. Place Regions::Region inside this portal and format it as a drop down with a value list listing the possible regions.
Now you can assign a doctor to multiple regions by selecting different regions in successive rows in the portal.
To get the listing you specify, create a list view, summary report based on the Regions table. You can add info from the related Doctors record by adding fields from the Doctors table to your layout.
If you don't want your regions listed in alpabetical order, you can speciy the same order as order of your regions in your value list to get an arbitrary order.