Impact of magnetic fields on small field dosimetry for parallel MR‐linacs

The impact of parallel magnetic fields of up to 1.0 T strength is minimal for in-water small field dosimetry. However, the increase in OF, compared to the 0 T case, was found to be significant for the 3.0 T magnetic field. For all field strengths compared to 0 T, significant dose differences were found around the periphery of the tumors inside a lung phantom that must be accounted for during treatment planning and dosimetry.