Are there any resources or literature that spell out the factors affecting image quality for each of the main imaging techniques or can someone provide such a list?
Here are some resources and books you can use but before that check out FDA ,radiologyeducation.com, virginia.edu , emory.edu and sprawls.org i think they can pretty much give you the information you want.
For fundamental information and physic of radiography ( which i think is the answer to your question) :
For MRI i recommend :
For PET scan :
CT scan :