Proton radiography imaging qualities have been studied using Monte Carlo simulations. A specific phantom, made of different common tissues, was implemented for simulations using the Massachusetts General Hospital treatment proton beam, pure 230- and 490-MeV proton beams, and a pure 100-keV X-ray beam. Along with spatial resolution, the signal-to-noise ratio and the contrast-to-noise ratio were specified and compared for each tissue type and geometry, using filtered radiographs taking into account only primary proton interactions, both primary and secondary proton interactions, and both contributions while performing angular and energetic cuts. This work particularly highlights the faculty for proton radiography to image both low- and high-density tissues. This could play an important role in diagnosing specific tumor types, such as lung cancer, for which conventional radiography operates poorly.