Flattening filter removal for improved image quality of megavoltage fluoroscopy

Abstract

The removal of the flattening filter from a clinical linac leads to quantifiable improvements in the image quality of megavoltage projection images. These gains enable observers to more easily visualize thin fiducial markers and track their motion on fluoroscopic images.

A multiresolution processing method for contrast enhancement in portal imaging

“…Several techniques have been investigated for improving the contrast of portal images: optimizing the acquisition process of the EPID (McGarry et al 2007), using low-Z targets (Connell and Robar 2009), using difference imaging (Kairn et al 2010), removing the flattening filter (Christensen et al 2013), stacking multiple detection layers and increasing the thickness of the scintillator (Rottmann et al 2016), and using Laplacian-of-Gaussian filters (Poels et al 2014). In addition, wavelet based methods have been implemented for contrast enhancement, like multiscale image contrast amplification (MUSICA) (Vuylsteke and Schoeters 1994).…”