Easy!
Actually could be done a couple of different ways:
1) You set your base rate at whichever level you want. Could even be $0. Then have a selection field where the user chooses their registration type... doctor, spouse, child, etc. Each selection value can have a matching fee value that adds a price amount or applies a discount. You could setup for group registration so say a doctor wants to register with a spouse and child. He'd register as a group of 3... then each group member selects their type so each one adds the correct price. This option would give a count of how many people are included towards the event capacity.
2) If your capacity is not a concern, you can go this route and not do group registrations. Set it for individual only. Give the doctor rate as the base fee. Add a selection field giving an option of including the spouse or not. If yes, then $X are added to the total. Then add a selection field (dropdown) for how many children to include. Add the appropriate fee for each value of the dropdown. These fields will add up all of the fees to give the total needed. This would probably be the simpler route for the user (maybe, matter of opinion) but would count as only ONE registrant in the event capacity.
So, either of these routes will work. Just determine what makes the most sense for your needs. Watch our video tutorial on Selection Fields. It will help a lot on this type of setup. Thanks!