The dose modulation transfer function concept (DMTF) in polymer dosimetry for quality control in fine photon fields

Abstract

There are different methods for obtaining access to quantitative information about the spatial resolution in dosimetric imaging. For polymer dosimetry these methods have mainly been based on comparisons between the dosimetric results of film or pin-point dose visualization to those of MR-based polymer dosimetry (MRPD) the resolution being typically 1 mm. With difference we present a more systematic approach as known from general imaging concepts based on the modulation transfer concept. We investigate periodic dose modulations in photon radiation fields down to spatial structures of a/2 = 280 μm (a: spatial period) using high resolution MR-microimaging at very small voxel sizes (Vs = 199 × 199 × 1000 μm3). The results are compared to those of a film scanner system as used for high resolution relative dosimetry in clinical routine.