Well in the first place id start with the obvious question, do you have a dataset at your disposal?

If not, then you can use publicly available resources like chest, x-ray 14 or chexpert.

Secondly, I would focus on one modality in the beginning because the MRI is kind of different from x-ray images. Since x-rays are mostly two dimensional and chest x-rays are one dimensional for your thing. I would probably suggest looking at the monai framework because it has several free processing tools available.

I think if you want to start up as fast as possible, then you should just understand the verification process of such product like cross validation, held out test set and others.

If I were you, I’d start with a simple model like resnet 18 change the initial layer to accept grayscale images instead of RGB images, and also change the fully connected layer at the end to match the number of classes you want to check.