ILO Classification
Encyclopedia
ILO Classification is a system of classifying radiographs (chest X-rays) for persons with pneumoconiosis
. The intent was to provide a means for describing and recording systematically the radiographic abnormalities in the chest provoked by the inhalation of dusts.
has been a specialized agency of the United Nations
, with objectives including establishing and overseeing international labor standards and labor rights. The International Labour Office ("ILO") is the Organization’s research body and publishing house. Since 1950, the ILO has periodically published guidelines on how to classify chest X-rays for pneumoconiosis. The purpose of the Classification was to describe and codify radiographic abnormalities of the pneumoconioses in a simple, systematic, and reproducible manner, aiding international comparisons of data, epidemiology, screening and surveillance, clinical purposes, and medical research. The most recent edition of the Guidelines, completed in 2000, replaced the 1980 revised edition.
In 1974, after studies of surveillance programs for coal miners revealed unacceptable degrees of interreader variablity, the National Institute for Occupational Safety and Health (NIOSH),began the "B" reader
program (so named because of the Black lung or Coal Workers' X-ray Surveillance Program), with the intent to train and certify physicians in the ILO Classification system. The "B" reader certification examination went into full operation in 1978. A physician must pass the certification examination to be a "B" reader.
, and asbestosis
. The reader then classifies the subject film, often recording the findings on the NIOSH Roentgenographic Interpretation form. The ILO Classification system pertains to pulmonary parenchymal abnormalities (small and large opacities), pleural changes (pleural plaques, calcification, and diffuse pleural thickening) and other features associated, or sometimes confused, with occupational lung disease.
The "Complete Set" of standard films consists of 22 radiographs: two illustrating normal profusion, fifteen of differing profusion category and shape/size of small opacity (see below), three illustrating large opacity, one of "u"-sized small opacity, and one of various pleural abnormalities. The "Quad Set" consists of 14 radiographs, nine of the most commonly used standards from the Complete Set, plus five additional composite reproductions of quadrant sections from the other radiographs in the Complete Set. Both sets are new and coincide with the newest ILO (2000) Guidelines.
Pneumoconiosis
Pneumoconiosis is an occupational lung disease and a restrictive lung disease caused by the inhalation of dust, often in mines.-Types:Depending upon the type of dust, the disease is given different names:...
. The intent was to provide a means for describing and recording systematically the radiographic abnormalities in the chest provoked by the inhalation of dusts.
History
Since 1946, the International Labour OrganizationInternational Labour Organization
The International Labour Organization is a specialized agency of the United Nations that deals with labour issues pertaining to international labour standards. Its headquarters are in Geneva, Switzerland. Its secretariat — the people who are employed by it throughout the world — is known as the...
has been a specialized agency of the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
, with objectives including establishing and overseeing international labor standards and labor rights. The International Labour Office ("ILO") is the Organization’s research body and publishing house. Since 1950, the ILO has periodically published guidelines on how to classify chest X-rays for pneumoconiosis. The purpose of the Classification was to describe and codify radiographic abnormalities of the pneumoconioses in a simple, systematic, and reproducible manner, aiding international comparisons of data, epidemiology, screening and surveillance, clinical purposes, and medical research. The most recent edition of the Guidelines, completed in 2000, replaced the 1980 revised edition.
In 1974, after studies of surveillance programs for coal miners revealed unacceptable degrees of interreader variablity, the National Institute for Occupational Safety and Health (NIOSH),began the "B" reader
"B" reader
A "B" reader is a physician certified by the National Institute for Occupational Safety and Health as demonstrating proficiency in classifying radiographs of the pneumoconioses.-History:...
program (so named because of the Black lung or Coal Workers' X-ray Surveillance Program), with the intent to train and certify physicians in the ILO Classification system. The "B" reader certification examination went into full operation in 1978. A physician must pass the certification examination to be a "B" reader.
Basic Description
The ILO Classification system includes the printed Guidelines and two sets of standard radiographs. The reader compares the subject chest X-ray (only the appearances seen on postero-anterior, or PA, chest film) with those of the standard set. The standard films provide differing types ("shape and size") and severity ("profusion") of abnormalities seen in persons with pneumoconiosis, including Coal Workers’ Pneumoconiosis, silicosisSilicosis
Silicosis, also known as Potter's rot, is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs...
, and asbestosis
Asbestosis
Asbestosis is a chronic inflammatory and fibrotic medical condition affecting the parenchymal tissue of the lungs caused by the inhalation and retention of asbestos fibers...
. The reader then classifies the subject film, often recording the findings on the NIOSH Roentgenographic Interpretation form. The ILO Classification system pertains to pulmonary parenchymal abnormalities (small and large opacities), pleural changes (pleural plaques, calcification, and diffuse pleural thickening) and other features associated, or sometimes confused, with occupational lung disease.
The "Complete Set" of standard films consists of 22 radiographs: two illustrating normal profusion, fifteen of differing profusion category and shape/size of small opacity (see below), three illustrating large opacity, one of "u"-sized small opacity, and one of various pleural abnormalities. The "Quad Set" consists of 14 radiographs, nine of the most commonly used standards from the Complete Set, plus five additional composite reproductions of quadrant sections from the other radiographs in the Complete Set. Both sets are new and coincide with the newest ILO (2000) Guidelines.
Methodology
- Film Quality:
- In the current ILO Classification system, the reader is first asked to grade film quality. There are four technical grades: (1) Good; (2) Acceptable, with no technical defect likely to impair classification; (3) Acceptable, with some technical defect but still adequate; and (4) Unacceptable. Quality defects include over- or under-exposure, underinflation, artifacts, improper positioning, and others.
- Parenchymal Abnormalities:
- Small Opacities: The reader will categorize small opacities according to shape and size. The small, rounded opacities are p (up to about 1.5 mm), q (about 1.5 mm to about 3 mm), or r (exceeding about 3mm and up to about 10 mm). Small, irregular opacities are classified by width as s, t, or u (same respective sizes as for small, rounded opacities).
- Lung Zones: Each lung is mentally subdivided by the reader into 3 evenly spaced zones: upper, middle, and lower. The zones in which the small parenchymal opacities appear are recorded.
- Profusion: Using the Standard X-rays, the profusion (concentration) of small opacities is classified on a 4-point major category scale (0, 1, 2, or 3), with each major category divided into three, giving 12 ordered subcategories of increasing profusion: 0/-, 0/0, 0/1, 1/0, 1/1, 1/2, 2/1, 2/2, 2/3, 3/2, 3/3, and 3/+. Category 0 refers to the absence of small opacity and category 3 represents the most profuse. The major category (first number) represents the profusion felt to best fit the subject film, and the minor category (second number) represents the profusion seriously considered as an alternative.
- Large opacities: A large opacity is defined as any opacity greater than 1 cm in diameter. They are classified as Category A (for one or more large opacities whose combined longest dimension does not exceed about 50 mm), category B (for one or more large opacities whose combined longest dimension exceeds 50 mm but does not exceed the equivalent area of the right upper lung zone), or category C (for one or more large opacities whose combined longest dimension exceed the equivalent area of the right upper lung zone).
- Pleural Abnormalities:
- Pleural abnormalities are reported with respect to type (pleural plaques or diffuse pleural thickening), location (chest wall, diaphragm, or other), presence of calcification, width (only of in profile pleural thickening seen along the chest wall edge), and extent (combined distance for involved chest wall).
- Any Other Abnormality:
- There are 29 "obligatory" symbols representing important features related to dust diseases of the lungs and other etiologies. These symbols are: aa atherosclerotic aortaAtherosclerosisAtherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
; at significant apical pleural thickening; ax coalescence of small opacities; bu bulla(e)EmphysemaEmphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...
; ca cancerLung cancerLung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...
; cg calcified granulomaGranulomaGranuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
or lymph node; cn calcification of small pneumoconiotic opacities; co abnormal cardiac shape or size; cp cor pulmonaleCor pulmonaleCor pulmonale or pulmonary heart disease is enlargement of the right ventricle of the heart as a response to increased resistance or high blood pressure in the lungs ....
; cv cavity; di marked distortion of an intrathoracic structure; ef pleural effusionPleural effusionPleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...
; em emphysemaEmphysemaEmphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...
; es eggshell calcificationSilicosisSilicosis, also known as Potter's rot, is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs...
; fr rib fracture(s)Rib fractureA rib fracture is a break or fracture in one or more of the bones making up the rib cage.The first rib is rarely fractured because of its protected position behind the clavicle . However, if it is broken serious damage can occur to the brachial plexus of nerves and the subclavian vessels...
; hi enlargement of non-calcified hilar nodes; ho honeycombing; id ill-defined diaphragm border; ih ill-defined heart border; kl septal (Kerley) lines; me mesotheliomaMesotheliomaMesothelioma, more precisely malignant mesothelioma, is a rare form of cancer that develops from the protective lining that covers many of the body's internal organs, the mesothelium...
. pa plate atelectasisAtelectasisAtelectasis is defined as the collapse or closure of alveoli resulting in reduced or absent gas exchange. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation.It is a very common finding in chest x-rays and other...
; pb parenchymal bands; pi pleural thickening of an interlobar fissure; px pneumothoraxPneumothoraxPneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...
; ra rounded atelectasis; rp rheumatoid pneumoconiosis; tb tuberculosisTuberculosisTuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...
; and od other disease or significant abnormality. Finally, the reader comments on any other abnormal features of the chest radiograph or other relevant Finally, the reader comments on any other abnormal features of the chest radiograph or other relevant information.