Practice Test Geeks(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test
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Image Quality Flashcards

7 cards from real ARRT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which artifact appears as a dark band between two high-density objects on a CT image and is caused by beam hardening?

    Answer: Shadowing or 'dark band' artifact

    Dark bands (also called 'shadowing' or 'cupping' between dense objects) arise from extreme beam hardening where few low-energy photons survive to reach the detector between two dense structures.

  2. A technologist reconstructs axial CT images with 5 mm thickness then reforms sagittal images showing 'staircase' appearance. The BEST solution is:

    Answer: Reconstruct using thinner overlapping slices before reformatting

    Staircase artifact on reformats results from thick axial slices; reconstructing thinner overlapping slices provides finer z-axis sampling and smoother multiplanar reformats.

  3. In CT, the term 'isotropic voxel' means:

    Answer: The voxel dimensions are equal in all three axes (x, y, z)

    An isotropic voxel has equal dimensions in x, y, and z directions, enabling multiplanar reformats of equal quality in any plane.

  4. The windmill artifact in multislice CT helical acquisitions is MOST pronounced when:

    Answer: High pitch values are combined with thick slice reconstruction

    Windmill artifact stems from undersampling in the z-direction; it is most visible with high pitch (sparse data) and thick reconstructions that exaggerate interpolation errors.

  5. A radiologic technologist notices that CT images of the liver appear uniformly noisy despite using standard mAs. The MOST appropriate first corrective action is:

    Answer: Verify that the correct reconstruction kernel and algorithm are applied

    Verifying protocol settings (kernel, algorithm, slice thickness) first ensures the source of apparent noise is identified before unnecessarily increasing dose.

  6. Which of the following BEST describes noise power spectrum (NPS) in CT?

    Answer: A measure of how noise is distributed across spatial frequencies in an image

    NPS characterizes the frequency content of image noise, showing whether noise is more granular (high-frequency) or blotchy (low-frequency) depending on reconstruction parameters.

  7. When comparing filtered back projection (FBP) to model-based iterative reconstruction (MBIR) at matched noise levels, MBIR typically demonstrates:

    Answer: Higher spatial resolution with fewer artifacts at lower dose

    MBIR models the entire imaging chain including optics and statistics, achieving better resolution and artifact suppression at lower dose than FBP.