Study Syllabus for Classification of Radiographs of Pneumoconioses
Section 2: Parenchymal Abnormalities (Continued)
The subcategories or minor categories are represented by fractional symbols. The number before the slash mark represents the major category of the ILO Standard that the radiograph most closely resembles. The number after the slash mark represents the major category of the ILO Standard that it next most closely resembles and that was, therefore, also seriously considered. If the radiograph so closely matches one ILO Standard that no other is seriously considered, the same major category number is recorded before and after the slash (since the ILO Standards represent the midpoints of the major categories, they more specifically represent minor categories 0/0, 1/1, 2/2 and 3/3 and are so identified). To classify a radiograph 2/2 means that it so closely matched the ILO 2/2 Standard that no other Standard was considered; to classify it 2/1 means that the subject radiograph most closely resembled the ILO 2/2 Standard, but that the ILO 1/1 Standard was also seriously considered.
In other words, the profusion of small opacities in the subject radiograph lies on the continuum between the midpoint of major category 1 and the midpoint of major category 2, but it is closer to 2 than to 1.
The assessment of profusion by placing the subject radiograph between ILO Standards does not apply at the extremes of the continuum. 0/- represents obvious, unequivocal absence of small opacities (the “cold normal”), whereas in 0/0, the midrange of major category 0, a few equivocal small opacities may be present. At the other end of the continuum, any profusion greater than that represented by ILO 3/3 Standard is indicated by 3/+.
Radiograph #4 (images A, B, C and D) illustrate a normal and the typical appearance of midrange, or approximate midrange, profusions for each major category of small opacity p.
Radiograph 4A is normal
Radiograph 4B shows a good example of p opacities at profusion 1/1 in the RUQ between the 2nd and 4th anterior interspaces. Note the A large opacity in the right upper zone.
Radiograph 4C shows a good example of p opacities at 2/2 profusion.
Radiograph 4D shows an example of 3/3 p/p.
Similarly, Radiographs #5 through #7 illustrate the typical midrange profusions for primary small opacities q, s, and t. Note, u opacities Radiograph #8 are quite rare, therefore the ILO 2011D analog standard is shown (Radiograph #8b) along with one example of u opacities in Radiograph #8c. As the major category increases from 1 to 2 to 3 the vascular pattern of the lung becomes progressively less distinct. Thus, the degree of vascular clarity may be of assistance in deciding the major category of profusion.
Radiograph 5A – Normal
Radiograph 5B – 1/1 q/q
Radiograph 5C – 2/2 q/q
Radiograph 5D – 3/3 q/q especially in the Right Upper Zone