Thallium scan or Angiography for disease evaluation

There are two tests commonly used for the detection of coronory artery disease i.e Thallium
Scan and Angiography.
Now adays Angiography has become very simple and the facility is available everywhere.
The doctors are still advising for the Thallium Scan test which , to my view point, is less
accurate and authentic than the angiography.
My question is that whether any different or important information could be taken by thallium
scan which cannot be judged by angiography or its simply the physcian's choice to adopt
the method of diagnostics.
In simple words why dont we go directly to angiography to have exact information about
the heart disease instead of opting for thallium scan which is old and less precise.

Thanks
Engr. Ahmad Saeed  

[kenkeith]

By definition an angiogram is vessel perfusion testing with contrast medium.  CAT scan angiogram (CTA).  CTA tests use computerized x-ray scanning and are a less invasive way to look at the heart, heart arteries and aortas. Both MRI and CTA tests form three-dimensional imaging of the areas under examination.  

State-of -art CT scan, 258 slice is in 3D and when slices are reassembled the image is very close to be live viewing and that includes blood flow (4D).

Thanks for your question,

Regards