I don't know exactly but the previous generation model had the hardware interlock that would have prevented this problem so it is possible. From Wikipedia: "O

I don't know exactly but the previous generation model had the hardware interlock that would have prevented this problem so it is possible. From Wikipedia: "One, when the operator incorrectly selected X-ray mode before quickly changing to electron mode, which allowed the electron beam to be set for X-ray mode without the X-ray target being in place. A second fault allowed the electron beam to activate during field-light mode, during which no beam scanner was active or target was in place. Previous models had hardware interlocks to prevent such faults, but the Therac-25 had removed them, depending instead on software checks for safety."