Why does inoculating with cowpox protect against smallpox but a standard flu vaccine cannot protect against every flu strain

The reason as why flu vaccine cannot protect each flu strain eventhough injecting cowpox provided cure for smallpox is that flu virus has the ability to mutate. The vaccine started last 1796 by Edward Jenner when a cowpox virus cured the boy from a smallpox.

Unlike  ct scans, which use x-rays,  mri scans  use powerful magnetic fields and radio frequency pulses to produce detailed pictures of organs, soft tissues, bone and other internal body structures.  differences between  normal and abnormal tissue is often clearer on an  mri  image than a  ct.you can see more with a mri scan. for example on an mri you can see internal bleeding.