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Fig 1. Low-contrast phantom. Phantom overview before CT scanning (A) and representative phantom image (window width, 100 HU; window level, 35 HU) (B). Two sets of 3-, 2-, and 1-cm-diameter acrylic resin spheres were embedded in an 18-cm-diameter cylindrical phantom. The attenuation was adjusted to 32 HU in one set of spheres (arrowheads), corresponding to complete cerebral infarction, and 34 HU in the other set of spheres (arrows), corresponding to early ischemic brain damage. The attenuation of the cylindrical phantom was 36 HU, corresponding to normal gray matter.
