NIOSH logo and tagline

Study Syllabus for Classification of Radiographs of Pneumoconioses

Radiograph Classification

Subset 1

Section 2: Parenchymal Abnormalities (Continued)

Radiograph #1

Demonstrates the difference in appearance between small rounded and small irregular opacities.

Radiograph 1p demonstrates excellent examples of p opacities between the left 2nd and 3rd anterior interspaces. Radiographs 1q and 1r show good examples of those opacity types respectively.

Radiograph 1s shows good examples of s opacities
Radiograph 1t the right lower zone shows good examples of t opacities.
Radiograph 1u is the ILO analog standard for u opacities. Chest radiographs with u opacities are very rarely seen.

With respect to size, small rounded opacities are defined in terms of their diameters:

p = up to about 1.5 mm
q = diameters exceed 1.5 mm and up to about 3 mm
r = diameters exceed 3 mm and up to about 10 mm

The sizes of small irregular opacities are expressed in terms of their widths:

s = up to about 1.5 mm
t = widths exceed 1.5 mm and up to about 3 mm
u = widths exceed 3 mm and up to about 10 mm

Radiograph #2

Presents a normal study, but then illustrates the differences in diameter that characterize small rounded (p, q, r) opacities.

Radiograph #3

Illustrates the differences in width that characterize small irregular (s, t, u) opacities.

Because u opacities are rare, radiograph 3u uses the current analog ILO standard as an example.

Note that the classification form has two sections for recording the size and shape of small opacities: primary and secondary. Determine the size and shape of any small opacities that may be present by comparing the subject radiograph with ILO Digital Standard Radiographs, which take precedence over written definitions. In the primary block, check the letter that refers to the size and shape of small opacities that predominate. If small opacities of some other size and shape are also present in significant numbers, check the letter that refers to the next most numerous type of opacity in the secondary block. If virtually all small opacities are of the same size and shape, check the same letter in both the primary and secondary blocks.