There's been a long discussion about this (and by long I mean it spans several Audition versions starting at CS and also spans several forum pages). I warn you it also gets rather acrimonious at times. You can view it here.
The long and short of it is that there's little you can do. Some people claim that there's a 3rd party programme called RX3 that can help; others (myself included) think the digital artifacts from that programme are more disturbing than the original echo. Since the problem on your recording is very subtle, my personal advice is not to mess with it but others may (or possibly will) disagree.
However, although it's too late for this shoot, it's worth saying that you could have all but eliminated any issues by positioning your lav differently. It's WAY too far down the lapel (it should be about half the distance from the mouth you have it) and, since the doctor is stood so as to speak slightly towards his left shoulder, the mic should either have been on the tie or on the left lapel. Have a look at the positioning of lavs on programmes like Letterman--they may seem random but they're always closer to the mouth and biased towards the side the talent will be mainly talking. It may seem simple but there's a bit of a skill to positioning clip on mics.