9
Table 1. Sources of Antigens Known to Cause HP
Matter Typical Sources HP "Disease"
Inorganic Particulate Matter
III. Metals
Cobalt Hard metals, alloys Giant cell
pneumonitis
Zinc (tungsten and alloys) Zinc fumes Zinc-fumes alveolitis
Zirconium Zircon Zirconium alveolitis
Beryllium Batteries, computers, neons Beryllium HP
TMI Organometallic compound for
semiconductors used in industry
—
(cont'd)
Table 2. 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)
