Nanakuli,

If a stand alone x-ray scanner can be hacked as you say to produce false images of objects passing through it, then why haven't other federal agencies, perhaps even the OMB, raised a ruckus about it?

I think the main reason roughly 95% of contraband items made it past TSA screeners in the 2015 test was the average quality of the personnel hired to fill TSA screener positions.  I don't believe even earning a high school diploma or its equivalent is a mandatory condition for employment.