Quite a project you are looking at there.
A couple of websites to start with would be:
www.asrt.org
(the professional association of radiographers)
www.arrt.org
(the registry of radiologic technologists, your accrediting organization)
on this site you can also find information about state licensing.
http://www.arrt.org/web/content.jsp?include=/licensing/certvslic.htm
You might want to look into this and contact some of the states to find out whether they would recognize your training.
Now, as for the visa you would qualify for:
H1b
- I know, your bsc is a 4 year degree. so, this could make you eligible for a H1b visa. However, RT is a 2 year associates degree in the US, therefore you might have a problem to get sponsored as plain RT. If a hospital however manages to write the job description in a way that it requires a 4 yeare college degree, you migh suceed.
There are numerical caps on the number of H1b visas, but if you worked for a non-profit hospital (most are), it is possible that you would be exempt from the cap.
Green-card (permanent resident visa)
- to obtain a GC, a hospital would have to proove that they couldn't find a US citizen to fill the job. Then they have to apply for a 'labor certification' which takes something like 4 months. After that they can petition the immigration service for an immigrant visa (another 6 months). Once that is approved, you could go to the embassy in London and obtain an immigrant visa into your passport (with another couple of months of waiting time). So, the lead time to go through this process is well over a year under the best circumstances. You might be able to find a rural hospital willing to do this. (at this time, there is an additional problem. there are more immigrants than immigrant visas, so people in the category you would fall into have to wait several years for visa numbers).
As for jobs:
WE NEED YOU. There is a shortage of qualified radiology technologists and ultrasonographers. There are plenty of jobs out there, however I am not sure whether many of these places will have the foresight to go through the immigration process for a candidate from abroad. Hospital administrators are extremely shortsighted people, but maybe you are lucky.