World’s Worst Software Bugs: The Therac-25 Disaster

How Poor Testing Practices Blasted Patients With Radiation

In June 1985, a woman named Katy Yarbrough visited an oncology center in Georgia.

She went into the treatment room, laid down on the table, and the operator set up the machine that would shoot focused beams of radiation at her breast cancer. It was all fairly routine.

But when the machine turned on, Yarbrough suddenly felt what she later described as a “red-hot sensation,” like she’d been burned…