ABSTRACT
Small photon fields have been used in stereotactic radiosurgery (SRS) for many years. Their use has recently been expanded into other applications of radiation therapy, as technological improvements in mechanical accuracy, stability, and dosimetric control made it possible for linacs to deliver complex intensity modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) that are composed of small fields. The impact of dosimetry of small fields on treatment quality also increased due to significant challenges not encountered in standard photon dosimetry before the era of IMRT/VMAT and SRS with small multileaf collimator (MLC) fields. Therefore, all aspects, including dosimetry, detector response, beam modeling, and geometry, of small fields need to be accurately characterized in order, so that treatment planning systems can correctly predict the delivered dose using small photon fields.
