Phase contrast imaging: Effect of increased object–detector distances at X-ray diagnostic and megavoltage energies

The effect of varying object to detector separation at constant and varying magnification has been investigated at an accelerating potential of 30 kVp. Edge-contrast enhancement provided by phase effects was investigated for a drinking straw and found to provide up to 2.52±0.02× the contrast for a PVC Heaviside step function. An optimum magnification of 1.5× was found to apply for the microfocus X-ray tube setup used. Imaging at nominal megavoltage energies was investigated using a Rapiscan Systems Eagle M4500 series scanner. For a fixed source–detector separation, increased magnification improved edge contrast and spatial resolution.