Scanning linear accelerator system for producing X-rays of variable controlled dose per pulse

A method for variably controlling X-ray dose during scanning of an object comprising the steps of

• providing a first control signal to an RF source and a second control signal to a source of electrons, the first and second control signals being independent of one another,
• in response to the first control signal, causing the RF source to supply to a linear accelerator RF pulses having an amplitude and a duration,
• in response to the second control signal, causing the electron source to supply to the linear accelerator pulses of controllable beam current at times substantially within the duration of a corresponding RF pulse,
• controlling the beam current pulses independently of the RF source to cause the linear accelerator to emit pulses of electrons controlled on a pulse-by-pulse basis and configured to strike a target for producing X-rays of controlled dose, wherein controlling the pulses of electrons from the linear accelerator comprises changing at least one of a group comprising electron source voltage, electron source pulse duration, RF source amplitude and RF source duration in order to vary dose per pulse so that the cab portion of a vehicle receives a first dose safe for humans while the cargo area of a vehicle receives a second dose at least 10× the first dose.