Specialty Segmentation: I would ask what type of "doctors" are you marketing to? MD, DO or perhaps PA's, NP's or ND's? Also are you looking to market to primary care, specialty, employed, private practice? Rural or Urban? Hospital-based or community outpatient based? Depending on your target market there are a variety of affinity groups you could then look to, all of which have various digital channels. An example would be radiologist (physicians who interpret medical imaging exam). They have many online forums they use frequently such as Auntminnie.com. The site has advertising, industry articles, and blogs. This might be the right place to target radiologists. Happy to have a conversation to help you think more about segmenting and targeting.