Adaptive pencil beam scanning

A method for producing an adaptive pencil beam having an adjustable lateral beam size and Bragg-peak width, comprising:

• selecting a momentum band expander from a set of momentum band expanders;
• receiving a pencil beam at the momentum band expander;
• widening a momentum spread of the pencil beam using the momentum band expander;
• passing the pencil beam through a slit to adjust the width of a Bragg-peak of the pencil beam;
• and
• adjusting a lateral size of the pencil beam.

A computer program product tangibly embodied in a computer-readable storage device and comprising instructions that when executed by a processor perform a method for producing an adaptive pencil beam having an adjustable lateral beam size and Bragg-peak widths, comprising:

• selecting a momentum band expander from a set of momentum band expanders;
• receiving a pencil beam at the momentum band expander;
• widening a momentum spread of the pencil beam using the momentum band expander;
• passing the pencil beam through a slit to adjust the width of a Bragg-peak of the pencil beam;
• and
• adjusting the lateral size of the pencil beam.

A method of providing treatment using an adaptive pencil beam, the method comprising:

• receiving a pencil beam at an adjustment element;
• producing the adaptive pencil beam using the adjustment element, wherein the adaptive beam comprises variable spot sizes;
• producing a first spot size comprising a steep dosage gradient for target tissue;
• producing a second spot size comprising a gradual dosage gradient for non-target tissue;
• splitting an energy layer of the adaptive pencil beam into sub-layers comprising the first spot size and the second spot size;
• and
• providing treatment using the sub-layers.