Washington Administrative Code › Title 246 - Health, Department of › RADIATION › Chapter 246-225 - Radiation protection - X rays in the healing arts › Section 246-225-160 - Mammography

Current through Register Vol. 24-14, July 15, 2024
(1) The use of a
				special purpose X-ray machine designed and used solely for mammography is
				required. Exempted from this requirement shall be X-ray equipment using
				xerography for evaluation of breast implant integrity.
(2) All mammographic calibration, evaluation,
				service, and quality control actions shall be documented in writing and
				maintained at the facility for a three-year period. Records must be easily
				accessible to operators of these X-ray units.
(3) All tests requiring the use of a breast
				phantom shall employ a phantom similar to or identical to the one required by
				the American College of Radiology for its mammography accreditation
				program.
(4) Machine requirements:
(a) Mammography X-ray machines must be
				evaluated upon any major component change and on a yearly basis by a qualified
				medical physicist. Evaluation shall document (but is not limited to) half-value
				layer (HVL), kVP accuracy, reproducibility, timer accuracy, resolution achieved
				with film in use at the facility, focal spot size, mA linearity, light versus
				X-ray field alignment, and patient exposures (glandular tissue dose) following
				the measurement protocol in NCRP Report No. 85 (using a breast phantom). This
				requirement shall include initial acceptance testing upon the X-ray system's
				installation prior to human use.
(b) The half-value layer (HVL) for
				film/screen mammography shall be between the values of measured kVp/100 and
				measured kVp/100 + 0.1 millimeters aluminum. The half-value layer for
				xerography shall be at least 1.2 mm but no greater than 1.6 mm of aluminum as
				measured at 50 kVP. The HVL shall include the contribution to filtration made
				by the compression device.
(c)
				Exposure reproducibility: Manual techniques. See WAC
				246-225-090.
(d) Exposure reproducibility: Photo-timed
				techniques. Mammographic systems in the AEC mode shall be able to maintain
				constant film density to within an optical density of ± 0.3 of the
				average optical density over the range of clinically used kVps, using BR-12 or
				other breast equivalent material phantom thicknesses of 2 centimeters to 6
				centimeters. If the facility has established a technique chart that utilizes
				varying technical factors for different breast thicknesses, those adjustments
				in technique may be used when complying with this requirement.
(e) Radiographic timers. See WAC
				246-225-070.
(f) kVP accuracy: The kVP accuracy published
				by the X-ray machine manufacturer shall be maintained at the specified level.
				For determination of actual versus indicated kVP, the manufacturer's
				recommendations for testing shall be followed.
(g) mA linearity. See WAC
				246-225-040(10).
(h) All special purpose X-ray machines
				designed solely for mammography and installed after January 1, 1992, shall be
				equipped with a milli-ampere-second (mAs) read-out device, registering after
				each phototimed exposure. Alternatively, a means of determining mAs after each
				exposure shall be provided.
(i)
				Beam limitation:
(i) Mammographic systems
				shall be provided with means to limit the useful beam such that the X-ray field
				at the plane of the image receptor does not extend beyond any edge of the image
				receptor at any designed SID except the edge of the image receptor designed to
				be adjacent to the chest wall where the X-ray field may not extend beyond such
				edge by more than two percent of the SID.
(ii) Beam limiting devices consisting of an
				assortment of fixed, removable cones sufficient to meet the requirement for
				each combination of image receptor size and SID for which the unit is designed
				shall have clear and permanent markings to indicate the image receptor size and
				SID for which it is designed.
(iii)
				When the beam limiting device and image receptor support device are designed to
				be used to immobilize the breast during a mammographic procedure and the SID
				may vary, the SID indication specified in WAC
				246-225-060(4)(c)(i) and
				(ii)    shall be the maximum SID for which the
				beam limiting device or aperture is designed.
(iv) In the absence of a visually defined
				X-ray field each image receptor support shall have clear and permanent markings
				to indicate the maximum image receptor size for which it is designed.
(j) The combination of
				source-to-image distance, magnification, and focal spot size shall result in a
				radiographic resolution of at least 12 line pairs per millimeter. This standard
				applies to the mammographic, single emulsion film being used at the
				facility.
(k) The X-ray machine
				shall be equipped with a means of immobilizing and compressing the breast with
				a force of at least twenty-five pounds but no greater than forty
				pounds.
(l) Dedicated mammographic
				X-ray units are exempted from the requirements of WAC
				246-225-030(5)(b)(i) provided that appropriate operator shielding
				is employed (as defined by NCRP Report 49).
(m)
Transmission limit for image
				receptor supporting devices used for mammography.
For X-ray systems
				manufactured after September 5, 1978, which are designed only for mammography,
				the transmission of the primary beam through any image receptor support
				provided with the system shall be limited such that the exposure 5 centimeters
				from any accessible surface beyond the plane of the image receptor supporting
				device does not exceed 25.8 nanocoulombs per kilogram (0.1 milliroentgen) for
				each activation of the tube. Exposure shall be measured with the system
				operated at the minimum SID for which it is designed. Compliance shall be
				determined at the maximum rated peak tube potential for the system and at the
				maximum rated product of tube current and exposure time (mAs) for that peak
				tube potential. Compliance shall be determined by measurements averaged over an
				area of 100 square centimeters with no linear dimension greater than 20
				centimeters.
(n) Maximum glandular
				doses. Glandular tissue dose for a cranio-caudal view of a 4.5 cm compressed
				breast using dose calculation methods found in NCRP Report # 85 shall not
				exceed the following: