Table 3.

Recommended Chest HRCT Scanning Parameters in the Diagnostic Approach of HP

1. Noncontrast examination

2. Volumetric acquisition with selection of:

• Submillimetric collimation

• Shortest rotation time

• Highest pitch

• Tube potential and tube current appropriate to patient size:

✓ Typically: 120 kVp and ≤240 mAs

✓ Lower tube potentials (e.g., 100 kVp) with adjustment of tube current encouraged for thin patients

✓ Use of techniques available to avoid unnecessary radiation exposure (e.g., tube current modulation)

3. Reconstruction of thin-section CT images (≤1.5 mm):

• Contiguous or overlapping

• Using a high-spatial-frequency algorithm

• Iterative reconstruction algorithm if validated on the CT unit (if not, filtered back projection)

4. Number of acquisitions

• Supine position: inspiratory (volumetric) and expiratory (sequential or volumetric) acquisitions

• Prone (optional): only inspiratory scans (can be sequential or volumetric)

• Inspiratory scans obtained at full inspiration

5. Recommended radiation dose for the inspiratory volumetric acquisition:

• 1–3 mSv (i.e., “reduced” dose)

• Strong recommendation to avoid “ultra–low-dose CT” (<1 mSv)

Definition of abbreviations: CT = computed tomography; HP = hypersensitivity pneumonitis; HRCT = high-resolution CT; kVp = kilovolt peak.

Adapted from Reference 20.