Section 37.41 - Chest radiograph specifications-film(a) Miners must be disrobed from the waist up at the time the radiograph is given. The facility must provide a dressing area and for those miners who wish to use one, the facility will provide a clean gown. Facilities must be heated to a comfortable temperature.(b) Every chest radiograph must be a single posteroanterior projection at full inspiration on a film being no less than 14 by 17 inches and no greater than 16 by 17 inches. The film and cassette must be capable of being positioned both vertically and horizontally so that the chest radiograph will include both apices and costophrenic angles. If a miner is too large to permit the above requirements, then the projection must include both apices with minimum loss of the costophrenic angle.(c) Chest radiographs of miners under this section must be performed: (1) By or under the supervision of a physician who makes chest radiographs in the normal course of practice and who has demonstrated ability to make chest radiographs of a quality to best ascertain the presence of pneumoconiosis; or(2) By a radiologic technologist as defined in § 37.2 .(d) Radiographs must be made with a diagnostic X-ray machine with a maximum actual (not nominal) source (focal spot) of 2 mm, as measured in two orthogonal directions.(e) Except as provided in this paragraph (e), radiographs must be made with units having generators that comply with the following:(1) The generators of existing radiographic units acquired by the examining facility prior to July 27, 1973, must have a minimum rating of 200 mA at 100 kVp;(2) Generators of units acquired subsequent to that date must have a minimum rating of 300 mA at 125 kVp.(f) Radiographs made with battery-powered mobile or portable equipment must be made with units having a minimum rating of 100 mA at 110 kVp at 500 Hz, or of 200 mA at 110 kVp at 60 Hz.(g) Capacitor discharge and field emission units may be used if the model of such units is approved by NIOSH for quality, performance, and safety. NIOSH will consider such units for approval when listed by a facility seeking approval under §§ 37.43 or 37.44 .(h) Radiographs must be given only with equipment having a beam-limiting device that does not cause large unexposed boundaries. The beam limiting device must provide rectangular collimation and must be of the type described in 21 CFR 1020.31(d), (e), (f), and (g) . The use of such a device must be discernible from an examination of the radiograph.(i) To ensure high quality chest radiographs: (1) The maximum exposure time must not exceed 50 milliseconds except that with single phase units with a rating less than 300 mA at 125 kVp and subjects with chests over 28 cm posteroanterior, the exposure may be increased to not more than 100 milliseconds;(2) The source or focal spot to film distance must be at least 6 feet;(3) Medium speed film and medium speed intensifying screens are recommended. However, any film-screen combination, the rated "speed" of which is at least 100 and does not exceed 300, that produces radiographs with spatial resolution, contrast, latitude and quantum mottle similar to those of systems designated as "medium speed" may be employed;(4) Film-screen contact shall be maintained and verified at 6 month or shorter intervals;(5) Intensifying screens shall be inspected at least once a month and cleaned when necessary by the method recommended by the manufacturer;(6) All intensifying screens in a cassette shall be of the same type and made by the same manufacturer;(7) A suitable grid or other means of reducing scattered radiation must be used;(8) The geometry of the radiographic system shall insure that the central axis (ray) of the primary beam is perpendicular to the plane of the film surface and impinges on the center of the film;(9) A formal quality assurance program shall be established at each facility.(j) Radiographic processing: (1) Either automatic or manual film processing is acceptable. A constant time-temperature technique shall be meticulously employed for manual processing.(2) If mineral or other impurities in the processing water introduce difficulty in obtaining a high-quality radiograph, a suitable filter or purification system must be used.(k) Before the miner is advised that the examination is concluded, the radiograph must be processed and inspected and accepted for quality by the physician, or if the physician is not available, acceptance may be made by the radiologic technologist. In a case of a substandard radiograph, another must be immediately made. All substandard radiographs must be clearly marked as rejected and promptly sent to NIOSH for disposal.(l) An electric power supply shall be used which complies with the voltage, current, and regulation specified by the manufacturer of the machine.(m) A test object may be required on each radiograph for an objective evaluation of film quality at the discretion of NIOSH.(n)(1) Each radiograph made hereunder must be permanently and legibly marked with:(i) The name and address or NIOSH approval number of the facility at which it is made;(ii) The miner's Social Security number;(iii) The miner's date of birth; and(iv) The date of the radiograph.(2) No other identifying markings may be recorded on the radiograph.43 FR 33715, Aug. 1, 1978, as amended at 52 FR 7866, Mar. 13, 1987; 77 FR 56729 , Sept. 13, 2012