Scanning system

A particle therapy system comprising:

• a particle accelerator to output a beam of charged particles;
• and
• a scanning system to scan the beam across at least part of an irradiation target, the scanning system comprising:
• a scanning magnet to move the beam during scanning, where a position of the beam corresponds to a current of the scanning magnet;
• and
• a control system (i) to control the current in order to produce uninterrupted movement of the beam across at least part of an irradiation target to deliver doses of charged particles, (ii) for positions at which the particle beam delivers dose, to store information identifying a location and an amount of dose delivered, (iii) to compare a cumulative dose delivered at each position to a target cumulative dose, and (iv) if the cumulative dose does not match the target cumulative dose at specific positions, control the current in order to move the beam so as to deliver additional dose to specific positions.