South Carolina Code of Regulations
Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL
Subchapter 61-64 - X-Rays (Title B)
Part V - QUALITY STANDARDS AND CERTIFICATION REQUIREMENTS FOR FACILITIES PERFORMING MAMMOGRAPHY
Section 61-64.V.RHB 5.13 - Equipment Quality Assurance Tests

Universal Citation: SC Code Regs 61-64.V.RHB 5.13

Current through Register Vol. 48, No. 9, September 27, 2024

5.13.1 Daily quality control tests. Film processors used to develop mammograms shall be adjusted and maintained to meet the technical development specifications for the mammography film in use. A processor performance test shall be performed on each day that examinations are performed before any clinical films are processed that day. The test shall include an assessment of base plus fog density, mid- density, and density difference, using the mammography film used clinically at the facility.

5.13.1.1 The base plus fog density shall be within plus 0.03 of the established operating level.

5.13.1.2 The mid-density shall be within plus or minus 0.15 of the established operating level.

5.13.1.3 The density difference shall be within plus or minus 0.15 of the established operating level.

5.13.2 Weekly quality control tests. Facilities with screen-film systems shall perform a phantom image quality evaluation test, using an FDA-approved phantom, at least weekly.

5.13.2.1 The optical density of the film at the center of an image of the phantom shall be at least 1.20 when exposed under a typical clinical condition.

5.13.2.2 The optical density of the film at the center of the phantom image shall not change by more than plus or minus 0.20 from the established operating level.

5.13.2.3 The phantom image shall achieve at least the minimum score established by the accreditation body.

5.13.2.4 The density difference between the background of the phantom and an added test object, used to assess image contrast, shall be measured and shall not vary by more than plus or minus 0.05 from the established operating level.

5.13.3 Quarterly quality control tests. Facilities with screen-film systems shall perform the following quality control tests at least quarterly:

5.13.3.1 Fixer retention in film. The residual fixer shall be no more than five micrograms per square centimeter (5 µg/cm2).

5.13.3.2 Repeat analysis. If the total repeat or reject rate changes from the previously determined rate by more than two percent (2%) of the total films included in the analysis, the reason(s) for the change shall be determined. Any corrective actions shall be recorded and the results of these corrective actions shall be assessed.

5.13.4 Semiannual quality control tests. Facilities with screen-film systems shall perform the following quality control tests at least semiannually:

5.13.4.1 Darkroom fog. The optical density attributable to darkroom fog shall not exceed 0.05 when a mammography film of the type used in the facility, which has a mid-density of no less than 1.20, is exposed to typical darkroom conditions for two (2) minutes while such film is placed on the counter top emulsion side up. If the darkroom has a safelight used for mammography film, it shall be on during this test.

5.13.4.2 Screen-film contact. Testing for screen-film contact shall be conducted using 40 mesh copper screen. All cassettes used in the facility for mammography shall be tested.

5.13.4.3 Compression device performance. The maximum compression force for the initial power drive shall be between one hundred eleven newtons (111 N)(25 lbs) and two hundred nine newtons (209 N)(45 lbs).

5.13.5 Annual quality control tests. Facilities with screen-film systems shall perform the following quality control tests at least annually:

5.13.5.1 Automatic exposure control (AEC) performance.
5.13.5.1.1 The AEC shall be capable of maintaining film optical density within plus or minus 0.30 of the mean optical density when the thickness of a homogeneous material is varied over a range of two to six centimeters (2 to 6 cm) and the kVp is varied appropriately for such thicknesses over the kVp range used clinically in the facility. If this requirement cannot be met, a technique chart shall be developed showing appropriate techniques (kVp and density control settings) for different breast thicknesses and compositions that shall be used so that optical densities within plus or minus 0.30 of the average under phototimed conditions can be produced.

5.13.5.1.2 After October 28, 2002, the AEC shall be capable of maintaining film optical density within plus or minus 0.15 of the mean optical density when thickness of a homogeneous material is varied over a range of two to six centimeters (2 to 6 cm) and the kVp is varied appropriately for such thicknesses over the kVp range used clinically in the facility.

5.13.5.1.3 The optical density of the film in the center of the phantom image shall not be less than 1.20.

5.13.5.2 Kilovoltage peak accuracy and reproducibility. The kVp shall be accurate within plus or minus five percent (5%) of the indicated or selected kVp at:
5.13.5.2.1 The lowest clinical kVp that can be measured by a kVp test device;

5.13.5.2.2 The most commonly used clinical kVp;

5.13.5.2.3 The highest available clinical kVp; and

5.13.5.2.4 At the most commonly used clinical setting of kVp, the coefficient of variation of reproducibility of the kVp shall be equal to or less than 0.02. The kVp shall be checked annually or upon new x-ray tube installation.

5.13.5.3 Focal spot condition. Until October 28, 2002, focal spot condition shall be evaluated by measuring focal spot dimensions or by determining system resolution. After October 28, 2002, facilities shall evaluate focal spot condition only by determining the system resolution. For focal spot dimensions, the measured values of the focal spot length (dimension parallel to the anode cathode axis) and width (dimension perpendicular to the anode cathode axis) shall be within the following tolerance limits:

Focal Spot Tolerance Limit

Nominal Focal Spot Size (mm)

Maximum Width (mm)

Measured Dimensions Length (mm)

0.10

0.15

0.15

0.15

0.23

0.23

0.20

0.30

0.30

0.30

0.45

0.65

0.40

0.60

0.85

0.60

0.90

1.30
5.13.5.3.1 System Resolution.
5.13.5.3.1.1 Each x-ray system used for mammography, in combination with the mammography screen-film combination used in the facility, shall provide a minimum resolution of eleven (11) cycles per millimeter (mm)(line-pairs/mm) when a high contrast resolution bar test pattern is oriented with the bars perpendicular to the anode cathode axis, and a minimum resolution of thirteen (13) line-pairs/mm when the bars are parallel to that axis.

5.13.5.3.1.2 The bar pattern shall be placed four and one-half centimeters (4.5 cm) above the breast support surface, centered with respect to the chest wall edge of the image receptor, and with the edge of the pattern within one centimeter (1 cm) of the chest wall edge of the image receptor.

5.13.5.3.1.3 When more than one (1) target material is provided, the measurement shall be made using the appropriate focal spot for each target material.

5.13.5.3.1.4 When more than one (1) source-image receptor distance is provided, the test shall be performed at the SID most commonly used clinically.

5.13.5.3.1.5 Test kVp shall be set at the value used clinically by the facility for a standard breast and shall be performed in the AEC mode, if available. If necessary, a suitable absorber may be placed in the beam to increase exposure times. The screen-film cassette combination used by the facility shall be used to test for this requirement and shall be placed in the normal location used for clinical procedures.

5.13.5.3.2 Focal spot dimensions. Measured values of the focal spot length (dimension parallel to the anode cathode axis) and width (dimension perpendicular to the anode cathode axis) shall be within the tolerance limits specified in this Part. The focal spot shall be checked annually or upon new x-ray tube installation.

5.13.5.4 Exposure Reproducibility. The coefficient of variation of exposure shall not exceed 0.05 for any specific combination of selected technique factors. This requirement shall be deemed to have been met if, when four (4) exposures are made at identical technique factors, the value of the average exposure ( E) is greater than or equal to five (5) times the maximum exposure (Emax) minus the minimum exposure (Emin): 5 (Emax - Emin). This requirement shall be checked annually or upon a new mammography x-ray unit or a new tube installation.

5.13.5.5 Timer Reproducibility. The coefficient of variation of the timer shall not exceed 0.05. This requirement shall be deemed to have been met if, with a selected timer setting, the average exposure period (T) shall be greater than or equal to five (5) times the maximum exposure period (Tmax) minus the minimum exposure period (Tmin) when four (4) timer tests are performed: T >= 5 (Tmax- Tmin). This requirement shall be checked annually or upon a new mammography x-ray unit or a new tube installation.

5.13.5.6 Timer Accuracy. Deviation of the selected time setting from indicated time values shall not exceed the limits specified for that system by its manufacturer. In the absence of manufacturer's specifications, the deviation shall not exceed ten percent (10%) of the indicated time value. This requirement shall be checked annually or upon a new mammography x-ray unit or a new tube installation.

5.13.5.7 Linearity. The following requirements apply when the equipment is operated on a power supply as specified by the manufacturer for any fixed x-ray tube potential within the range of forty percent to one hundred percent (40% to 100%) of the maximum rated:
5.13.5.7.1 Equipment having independent selection of x-ray tube current (mA). The average ratios of exposure to the indicated milli Ampere-seconds product (C/kg/mAs (or mR/mAs)) obtained at any tube current settings shall not differ by more than 0.10 times their sum. This is: [X1-X2] < 0.10 (X1+X2); where X1 and X2 are the average C/kg/mAs (or mR/mAs) values obtained at any two (2) tube current settings.

5.13.5.7.2 Equipment having a combined x-ray tube current-exposure time product (mAs) selector, but not a separate tube current (mA) selector. The average ratios of exposure to the indicated milliAmpere-seconds product (C/kg/mAs (or mR/mAs)) obtained at any two mAs selector settings shall not differ by more than 0.10 times their sum. This is [X1-X2] <0.10 (X1+X2); where X1 and X2 are the average C/kg/mAs (or mR/mAs) values obtained at any two mAs selector settings.

5.13.5.7.3 Measuring Compliance. Determination of compliance shall be based on four (4) exposures, at each of the two (2) settings. The two (2) settings may include any two (2) focal spot sizes provided that neither focal spot size is equal to or less than .45 millimeter, in which case the two (2) settings shall be restricted to the same focal spot size. For purposes of this requirement, focal spot size is the nominal focal spot size specified by the tube manufacturer. Linearity shall also be checked annually or upon new x-ray tube installation.

5.13.5.8 Beam quality and half-value layer (HVL). For mammography systems operating at x-ray tube potentials of less than fifty kilovoltage peak (50 kVp), the HVL in millimeters of aluminum of the useful beam shall be equal to or greater than the product of the measured tube potential in kilovolts multiplied by 0.01. The HVL shall be measured with the compression device in the beam and shall be measured at the same tube potential used in Appendix A of this Part, Mammography Dose Measurement Protocol, and Appendix B of this Part, Mammography Phantom Image Evaluation. The HVL shall be checked annually and after repairs to the system have been made that could affect the filtration or upon new x-ray tube installation.

5.13.5.9 Breast entrance air kerma and AEC reproducibility. The coefficient of variation for both air kerma and mAs shall not exceed 0.05.

5.13.5.10 Dosimetry. The average glandular dose delivered during a single craniocaudal view of a phantom simulating a standard breast shall not exceed 3.0 milligray (mGy) (0.3 rad) per exposure. The dose shall be determined with technique factors and conditions used clinically for a standard breast. The average glandular dose shall be checked annually or upon new tube installation.

5.13.5.11 X-ray field/light field/image receptor/compression paddle alignment.
5.13.5.11.1 All systems shall have beam-limiting devices that allow the entire chest wall edge of the x-ray field to extend to the chest wall edge of the image receptor and provide means to assure that the x-ray field does not extend beyond any edge of the image receptor by more than two percent (2%) of the SID. This requirement is for both large and small cassettes sizes.

5.13.5.11.2 If a light field that passes through the x-ray beam limitation device is provided, it shall be aligned with the x-ray field so that the total of any misalignment of the edges of the light field and the x-ray field along either the length or the width of the visually defined field at the plane of the breast support surface shall not exceed two percent (2%) of the SID.

5.13.5.11.3 The chest wall edge of the compression paddle shall not extend beyond the chest wall edge of the image receptor by more than one percent (1%) of the SID when tested with the compression paddle placed above the breast support surface at a distance equivalent to standard breast thickness. The shadow of the vertical edge of the compression paddle shall not be visible on the image.

5.13.5.12 Uniformity of screen speed. Uniformity of screen speed of all the cassettes in the facility shall be tested and the difference between the maximum and minimum optical densities shall not exceed 0.30. Screen artifacts shall also be evaluated during this test.

5.13.5.13 System artifacts. System artifacts shall be evaluated with a high-grade, defect-free sheet of homogeneous material large enough to cover the mammography cassette and shall be performed for all cassette sizes used in the facility using a grid appropriate for the cassette size being tested. System artifacts shall also be evaluated for all available focal spot sizes and target filter combinations used clinically.

5.13.5.14 Radiation output.
5.13.5.14.1 The system shall be capable of producing a minimum output of 4.5 Gy air kerma per second (513 mR per second) when operating at twenty-eight kilovoltage peak (28 kVp) in the standard mammography (moly/moly) mode at any SID where the system is designed to operate and when measured by a detector with its center located four and one-half centimeters (4.5 cm) above the breast support surface with the compression paddle in place between the source and the detector. After October 28, 2002, the system, under the same measuring conditions, shall be capable of producing a minimum output of 7.0 Gy air kerma per second (800 mR per second) when operating at twenty-eight kilovoltage peak (28 kVp) in the standard (moly/moly) mammography mode at any SID where the system is designed to operate.

5.13.5.14.2 The system shall be capable of maintaining the required minimum radiation output averaged over a 3.0-second period.

5.13.5.15 Decompression. If the system is equipped with a provision for automatic decompression after completion of an exposure or interruption of power to the system, the system shall be tested to confirm that it provides:
5.13.5.15.1 An override capability to allow maintenance of compression;

5.13.5.15.2 A continuous display of the override status; and

5.13.5.15.3 A manual emergency compression release that can be activated in the event of power or automatic release failure.

5.13.6 The quality assurance requirements of RHB 4.2.16 and film processing requirements of RHB 4.2.17.2 shall be met except where otherwise mentioned.

5.13.7 Quality control tests - other modalities. For systems with image receptor modalities other than screen-film, the quality assurance program shall be substantially the same as the quality assurance program recommended by the image receptor manufacturer, except that the average glandular dose must meet the requirements of RHB 5.13.5.10.

5.13.8 Mobile Units. The facility shall verify that mammography units used to produce mammograms at more than one (1) location meet the requirements in RHB 5.13.1 through 5.13.7. In addition, at each examination location, before any examinations are conducted, the mobile mammography system shall be tested using the mammography phantom image evaluation to establish the adequacy of the image quality produced by the unit.

5.13.9 Use of test results.

5.13.9.1 After completion of the tests specified in RHB 5.13.1 through 5.13.8, the facility shall compare the test results to the corresponding specified action limits; or for non-screen film modalities, to the manufacturer's recommended action limits; or for post-move, pre-examination testing of mobile units, to the limits established in the test method used by the facility.

5.13.9.2 If the test results fall outside the action limits, the source of the problem shall be identified and corrective actions shall be taken and documented:
5.13.9.2.1 Before any further examinations are performed or any films are processed using the component of the mammography system that failed any of the tests described in RHB 5.13.1, 5.13.2, 5.13.4.1, 5.13.4.2, 5.13.4.3, 5.13.5.10, 5.13.6, 5.13.7, or 5.13.8.

5.13.9.2.2 Within thirty (30) calendar days of the test date for all other tests described in RHB 5.13.

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