Hello Sheldon,
I am also a canadian radiologist (province of Quebec) and computer engineer, starting research using deep learning. That is good to know your interest !
I would first try to copy the grayscale channel in the RGB channels and just try different pretrained models (VGG16, Inception V3, Xception, Resnet50) with different images resolution to see the result. Depending on the results, this will give you hints on where to go after.
Your point about using easy known labels as pretraining is an excellent point. I am trying a similar idea with cerebral CT ! Basically, the intuition is that a model needs to learn anatomy before learning pathology ! I totally agree with your hypothesis !
I am actually in the process of getting the approvals for data access. We basically want to follow the same path. So that could be a nice opportunity to collaborate and share our experience in this area.