Quality Assurance

PURPOSE: This rule establishes requirements for calibration of mammography equipment and monitoring of the mammography system. (1) All variable parameters of the equipment shall be calibrated as follows: (A) When the equipment is first installed; (B) After any major changes or replacement of parts; (C) At least annually while in use; and (D) When quality assurance tests indicate that calibration is needed. (2) The following parameters of the system shall be monitored as follows: (A) Processor performance shall be monitored on a daily basis to include solution temperatures, sensitometric-densitometric evaluation through the use of control charts which shall include speed step or mid-density step with a control limit of plus or minus fifteenhundredths optical density (±0.15 OD), contrast index or density difference with a control limit of plus or minus fifteen-hundredths optical density (±0.15 OD) and base plus fog with a control limit of plus three-hundredths optical density (+.03 OD) of the operating level; (B) Processor chemical replenishment rates shall be monitored at least quarterly; (C) Half-value layer shall be determined at least annually with the compression device located in the primary beam, halfway between the image receptor assembly and the X-ray tube; (D) Milliampere-seconds (mAs) linearity shall be determined at least annually based on the average ratios of exposure to the indicated milliampere-seconds product (mR/mAs) obtained at any two (2) consecutive tube current settings, which shall not differ by more than ten-hundredths (0.10) times their sum as measured with a minimum of four (4) consecutive exposures or a maximum of ten (10) consecutive exposures at commonly used settings; (E) Manual and automatic exposure control (AEC) reproducibility shall be determined at least annually based on the coefficient of variation of exposures, which shall not be greater than plus or minus five percent (±5%) as measured with a minimum of four (4) consecutive exposures or a maximum of ten (10) consecutive exposures at a commonly used setting; (F) Kilovoltage potential (kVp) accuracy shall be determined at least annually. The actual kVp shall be maintained within plus or minus five percent (±5%) of the indicated kVp; (G) kVp reproducibility shall be determined at least annually based on the coefficient of variation of kVp values, which shall not be greater than plus or minus five percent (±5%) as measured with a minimum of four (4) consecutive exposures or a maximum of ten (10) consecutive exposures at commonly used kVp settings; (H) AEC thickness response shall be determined at least annually based on film density, which shall be maintained within plus or minus three-tenths optical density (±0.3 OD) of the average OD over the kVp range used for phantom thicknesses of two, four and six centimeters (2, 4 and 6 cm). If the OD cannot be maintained to within plus or minus three-tenths (‰0.3) of the average of each clinically used setting, a technique chart shall be developed that alters kVp and density control settings as a function of breast thicknesses and densities to produce optical densities within this range under phototimed conditions; (I) Compression device response shall be monitored at least annually; (J) Adequacy of film storage shall be monitored at least annually, both before use and after exposure, if processing does not occur immediately; (K) Availability and use of technique charts that shall include an indication of the kV-target-filter combination to be used with each image receptor shall be monitored at least annually; (L) The use of kV-target-filter combination appropriate to the image receptor shall be monitored daily before patient irradiation; (M) Darkroom integrity, for light-tight conditions and use of proper safelight, shall be monitored at least semiannually and whenever bulbs or filters are changed or when fog is suspected; darkroom fog levels shall have a variance of not greater than five-hundredths (0.05) density units between the fogged and unfogged film based on a two (2)-minute exposure to the darkroom safelight; (N) Image quality, using one (1) of the following mammography phantoms; the RMI 152, the RMI 156, the CIRS, the Nuclear Associates phantom or other equivalent phantom acceptable to the Department of Health, which simulates the composition of the breast and provides indicators of disease conditions allowing objective analysis of clinical image quality, shall be monitored at least monthly and each time the mammographic equipment is moved or altered in any major way including the replacement of parts; a phantom image shall be made and evaluated for mobile units and vans at each location prior to the performance of mammography; (O) Average glandular dose shall be determined at least annually based on measurements of estimated skin entrance exposure; the average glandular dose shall be calculated from those used for imaging a four and fivetenths centimeters (4.5 cm) compressed breast in the cranial caudal view and the measurement point shall be four and five-tenths centimeters (4.5 cm) from the surface of the grid or cassette as appropriate; and (P) Film-screen contact shall be monitored at least semiannually and when new or repaired cassettes/screens are placed in service, using a contact test tool specifically designed for mammography; cassettes/ screens shall be cleaned at least weekly; for xeroradiography, the photoreceptor plates shall be maintained in accordance with the manufacturer’s specifications. (3) Evaluation of monitoring results— (A) Standards of image quality giving acceptable ranges of value for each of the parameters tested shall be established to aid in the evaluation of monitoring results. The standards of image quality related to dose shall include a requirement that the average glandular dose for one (1) cranial caudal view of a four and five-tenths centimeters (4.5 cm) compressed breast fifty percent (50%) glandular/fifty percent (50%) adipose composition shall not exceed one hundred (100), three hundred (300) and four hundred (400) millirads (mrads) for film/screen units without grids, film/screen units with grids, and xeroradiography units, respectively; and (B) The monitoring results shall be compared routinely to the standards of image quality established by the Department of Health. If the results fall outside the acceptable range, the test shall be repeated. If the results continue to be unacceptable, the source of the problem shall be identified and corrected before further examinations are conducted. (4) A program to analyze retakes shall be established to detect and correct problems affecting image quality or exposure. This analysis shall be performed at least quarterly or after two hunndred fifty (250) patients, whichever comes first. (5) All quality assurance test equipment shall be in good operating order and calibrated according to the manufacturer’s specifications. AUTHORITY: sections 192.762 and 192.766, RSMo. Supp. 1992.* This rule was previously filed as 19 CSR 20-11.080. Emergency rule filed Oct. 5, 1992, effective Oct. 15, 1992, expired Feb. 12, 1993. Emergency rule filed Feb. 3, 1993, effective Feb. 13, 1993, expired June 12, 1993. Original rule filed Nov. 4, 1992, effective June 7, 1993. Changed to 19 CSR 30-11.080 July 30, 1998. *Original authority 1992.