I mostly agree with the above. Simply put, technologists use imaging devices to produce images for radiologists to interpret medically. They have an important job in producing high quality imaging for the physician. In addition, technologists are generally very familiar with the particular device that they use-- they know the intimate specifics of a particular machine.
Having said that, in terms of the fundamentals of image production which MacGyver is alluding to (i.e. for MR, specific pulse sequences appropriate for imaging different anatomy/pathology), in my experience radiologists are very knowledgeable. Although not everybody is a phd in physics, rads residency includes a lot about the principles of imaging, especially in the context of how to effectively image different pathology (and what is NOT seen...). The radiology dept. is a team environment, not a competition, and I have met some techs who are very knowledgeable, but ultimately the decision about how to best image something ("protocoling") -- as well as the imaging dignosis -- is made by the radiologist. In addition, it has mainly been radiologists & other physicians (and basic scientists) who have contributed to advances in imaging, and it is the radiologist who is responsible for ensuring that his/her facility stays on the technological (and medical-diagnostic) cutting edge through continuing education/improvements.
This is not to minimize the fact that techs, over time develop a wealth of practical experience in imaging (i.e. patient positioning, workflow maximization, machine parameters, etc.) that ultimately contributed to a efficiently running imaging facility. You can often see the difference betwen images produced by a seasoned tech vs. a new graduate.
In my experience, the MDs and techs have different types of knowledge when it comes to imaging, and both are essential in the running of a radiology department. The centers I have worked in have had very collegial environments.
