Reducing Radiation Dose in CT Enterography

Standard CT enterography is described and dose-reduction strategies are presented.

Course ID: Q00397 Category:


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Targeted CE per ARRT’s Discipline, Category, and Subcategory classification:

Computed Tomography: 2.50
Safety: 2.00
Radiation Safety and Dose: 2.00
Procedures: 0.50
Abdomen and Pelvis: 0.50

Registered Radiologist Assistant: 2.50
Safety: 2.00
Patient Safety, Radiation Protection and Equipment Operation: 2.00
Procedures: 0.50
Abdominal Section: 0.50


  1. Introduction
  2. Standard CT Enterographic Techniques
    1. Quantifying CT Radiation Dose
    2. Low-Dose CT Enterography
      1. Scan Coverage
      2. Tube Potential
      3. Tube Current
    3. Tube Current Modulation and Automatic Exposure Control
      1. Patient Size Modulation
      2. Z-Axis Modulation
      3. XñY-axis (Angular) Modulation
  3. Synergy of Kilovoltage Selection, Tube Current Modulation, and Size Adaptation
  4. Noise-Reduction Methods and Iterative Techniques
    1. Comparison of Denoising Techniques
      1. True Iterative Reconstruction: MBIR and Iterative Reconstruction Prototypes
      2. Iterative Noise-Reduction Methods: ASIR and SAFIRE
      3. Image Space Denoising
      4. Projection Space Denoising
    2. Synergy of Denoising Methods
  5. Challenges of Low-Dose CT Enterography
  6. Conclusion


Upon completion of this course, students will:

  1. be familiar with the purpose for evaluating patients with CT enterography
  2. identify the strategies for reducing radiation dose at CT enterography
  3. be familiar with the advantages of CT enterography
  4. be familiar with the most common indication for performing CT enterography
  5. identify the patient symptoms related to Crohn disease
  6. be familiar with the number of CT acquisitions to evaluate GI bleeding
  7. be familiar with the volume of oral contrast administered for CT enterography
  8. identify the rate of i.v. contrast administration recommended for CT enterography
  9. be familiar with the acronym CTDI
  10. understand how the CTDI is measured at axial scanning
  11. be familiar with the international system of units for CTDIvol
  12. be able to identify what the CTDI measures
  13. understand how the DLP is calculated
  14. be familiar with the increase in radiation dose during standard triphasic CT enterography
  15. be familiar with excluded unwanted anatomy to reduce radiation dose in CT enterography
  16. understand how to properly adjust kVp related to patient size
  17. identify the types of CT automatic exposure controls
  18. be familiar with the increase of radiation exposure to the U.S. population
  19. identify the current campaigns to reduce radiation exposure
  20. be familiar with the development of CTDI
  21. understand how the CTDIvol is calculated
  22. identify the CT dose descriptors most commonly used in the U.S.
  23. be familiar with the dimensions of the standard CT dosimetry phantoms
  24. understand which factors affect the radiation dose to a patient during CT
  25. be familiar with the effect of reducing radiation dose on CT image noise
  26. identify the historically most common analytic algorithm for reconstructing CT images
  27. be familiar with the physical effects being incorporated during iterative reconstruction
  28. identify the primary disadvantage of using iterative reconstruction
  29. be able to identify CT noise reduction methods
  30. be familiar with the way different iterative reconstruction processes work
  31. identify the filters used when using image space denoising
  32. be familiar with the factors that can affect CT spatial resolution
  33. be familiar with the history of image reconstruction
  34. understand the definition of CT artifact
  35. identify image artifacts that can be experienced in CT