I have been told by multiple MRT's and Radiologists not to refer to an MRT as an X-Ray Technician as it is viewed as demeaning (not to say an X-Ray technician is less deserving of respect, but it would be akin to calling a doctor a nurse or a nurse a janitor -- all respectable professions but quite different levels of training).
It is true that in some places, for example, the USA, the training they receive is quite limited.
However in Canada and the UK, for example, training is much more in depth and the job involves more than simply pressing a button.
The job involves (to name a few things): Prepping the patient for the procedure (example: administering the contrast agent, normally through IV or orally, though sometimes it goes in other holes as you should know); getting a drug history, etc.
Monitoring for any adverse reactions to the contrast, etc. Performing the actual procedure and acquiring the images. Making any necessary notes about the image etc (artifacts, issues, anything the patient didn't initially tell the physician, etc.)
Ensuring patient is not exposed to unnecessary dose and avoiding exposing a fetus, etc.
Controlling the technical factors (different people, conditions, body parts etc require different KVP and MAS settings on the machine to avoid overexposing the patient and to achieve a diagnostic quality X-ray).
While direct interaction between MRT and Radiologist is often limited in general X-Ray (excluding stress views) the two often work together for fluoroscopy. In some parts of the UK they even assist with the diagnosis. There are more parts to the job, but that covers a few of the obvious ones.
To clarify "In some cases, x-ray technicians venture into using other imaging technology besides x-rays, performing MRIs, CAT scans, and even ultrasounds," an MRT is qualified to perform a CT (cat scan) but must go through additional schooling to be qualified to perform an MRI or ultrasound.