English to Russian Medical Medical: Instruments

LOW CONTRAST OBJECT DETECTABILITY
Failure of this test can be caused by the phantom being tilted. A tilted phantom leads to parts of the slices being out of their proper location, and therefore to the same sort of problem as just described for incorrectly positioned slices. In this regard, tilt (rotation) about the inferior-superior axis of the phantom is not a problem, but tilt about the other two axes can be. Tilt about the right-left axis will be readily apparent on the localizer. If the phantom does not look square with the edges of the field of view on the localizer, it should be repositioned before continuing to acquire data. The non-magnetic bubble level that accompanies the phantom can be used to level the phantom in the knee coil to avoid this kind of tilt. Tilt about the anteriorposterior axis is harder to see on the images. It can often be detected as right-to-left fade of structures that should show uniform partial-volume effects across an axial slice. The best way to avoid this kind of tilt is to carefully align the phantom squarely in the knee coil.