Processor Performance - Daily QC Tests

Questions Key Words/Related Topics

Citation:

900.12(e)(1)(i),(ii),(iii): 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 clinical films are processed 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.

(i) The base plus fog density shall be within +0. 03 of the established operating level.

(ii) The mid-density shall be within ±0.15 of the established operating level.

(iii) The density difference shall be within ±0.15 of the established operating level.

Approved Alternative Standard:

Daily Processor QC Tests

Discussion:

Question 1: Is an intermittently used processor (so called back-up processor) held to the same QC standards as the primary mammography processor?

Question 2: What about QC on mammography processors that are also used to develop films for copying mammograms and for laser films that are used in digital mammography?

Question 3: Must a facility perform the daily processor QC tests on days when mammograms are performed but not processed?

Question 4: We have a separate processor that we only use to make mammography copies. Are there any MQSA requirements that this processor has to meet?

Question 5: We are sending our densitometer out for a regularly scheduled calibration. While it is gone, how can we continue with our daily quality control program until it is returned? Can we use a "loaner" densitometer or perform some substitute test in the interim?

Question 6: Must all facilities use 5 days to establish operating levels in a processor or can they use a longer period?

Question 7: In which situations should facilities establish new processor operating levels?

Question 8: During the time a facility is establishing new processor operating levels (typically done by performing a five-day data plot average): A) does the facility continue to plot the data on the processor chart?; B) Is the facility exempt from having to stay within the old processor action limits during the five-day averaging period?

Question 1: Is an intermittently used processor (so called back-up processor) held to the same QC standards as the primary mammography processor?

Yes. Intermittently used (so called back-up) processors used for mammography will be held to the same quality standards as the primary processor(s) used for mammography. It is the responsibility of the facility to assure that the processor is in control (monitored parameters are within the action limits) before processing any clinical images. One way to achieve this is to establish a baseline for any processor that might be used as a back-up for processing mammograms. Subsequently, on the day the back-up processor is needed, the daily processor QC tests should be performed prior to processing clinical images and if the test results fall outside the action limits, clinical images should not be processed until all problems have been fixed and the new test results show that the processor is in control.

Question 2: What about QC on mammography processors that are also used to develop films for copying mammograms and for laser films that are used in digital mammography?

Films that are used to copy mammograms (duplicating or copy films but not laser films) generally alter the performance of the processor by degrading the chemicals in the processor. This does not significantly affect processor performance if a small number of copies are made at a time. However, if a large number of copies is produced on a given day, FDA recommends that the daily processor QC tests be performed after the copies have been processed and prior to processing the clinical images.

Question 3: Must a facility perform the daily processor QC tests on days when mammograms are performed but not processed?

Facilities are required to perform these tests only on the days they process mammograms. However, FDA recommends that facilities that routinely process mammograms less than 5 days/week perform the daily processor QC tests on additional days. The additional tests can provide the facility more information to predict trends and thereby identify and correct problems earlier.

Question 4: We have a separate processor that we only use to make mammography copies. Are there any MQSA requirements that this processor has to meet?

No. There are no MQSA requirements for processors that are used only for copying mammograms. However, if such a processor is also used to process original mammograms, then you must perform processor QC on it and assure that it is in control before you use it to process mammograms.

Question 5: We are sending our densitometer out for a regularly scheduled calibration. While it is gone, how can we continue with our daily quality control program until it is returned? Can we use a "loaner" densitometer or perform some substitute test in the interim?

The daily processor quality control is required prior to processing patient films. No alternative is currently available to verify processor performance without a densitometer. If your facility plans to use a loaner densitometer, reintroduce one into service after repair/calibration, or obtains a new densitometer, you should contact your medical physicist for instructions on how to proceed.

Question 6: Must all facilities use 5 days to establish operating levels in a processor or can they use a longer period?

The 5-day period is not a regulatory limit. Therefore, a facility may use a shorter or longer period if their situation calls for it. The number of days needed to establish the operating levels depends on the time it takes for the processor to reach chemical equilibrium or a "seasoned" status. In practice, this is usually achieved when the chemicals in the developer tank have been replaced or "turned over" 2-3 times.

For a given film, this time is a function of the developer tank size, the replenishment rate, and the number of films processed (patient volume). Also, different film emulsion types have different replenishment rates per sheet of film, thus requiring different periods for the same processor to reach a seasoned status.

Based on experience to date, we expect the majority of facilities to use up to a 5-day averaging period. However, if a facility uses a longer period, it should provide empirical data or recommendations from the film manufacturer explaining the reasons for the longer time period. Regardless of the length of time needed for establishing or re-establishing operating levels, the facility must document the MD, DD, and B+F values daily. Even though there are no regulatory action limits during this period, monitoring of processing conditions is still important as these values may identify problems with developer temperature, replenishment rates, and other variables.

Question 7: In which situations should facilities establish new processor operating levels?

The most warranted and common situations for a facility to establish new processor operating levels are when processor QC testing is initiated for a new processor or when a significant change is made in the processing system. Some significant changes that may necessitate the establishment of new operating levels include: change in film brand/type, change in chemical brand/type, change in replenishment rates, change in specific gravity automixer settings, change of sensitometer or densitometer, or a change in processing conditions (standard vs. extended). Replacement of chemistry (same brand/type) as part of routine preventative maintenance should not necessitate establishment of new operating levels.

Facilities should not use the establishment of new operating levels to correct problems in the processing system, but should troubleshoot and solve the problem with appropriate corrective action. FDA recommends that the facility consult with its medical physicist prior to establishing new operating levels.

Question 8: During the time a facility is establishing new processor operating levels (typically done by performing a five-day data plot average): A) does the facility continue to plot the data on the processor chart?; B) Is the facility exempt from having to stay within the old processor action limits during the five-day averaging period?

While establishing new processor operating levels (during which time the facility can continue to process mammograms), the facility must continue to perform the daily processor QC tests and should plot the data in the same manner it usually does. This may be done on the same graph as the previous data or on a different graph. In either event, this new data should be clearly identified as being derived during the establishment of the new operating levels, so that both the facility and the inspector are aware of the origins of this data. Because no operating level has yet been established, the facility is exempt from having to stay within any processor action limits during this five-day averaging period. FDA recommends that during the five-day averaging period, the facility daily perform and evaluate a phantom image as a means of monitoring image quality. Because phantom optical densities may also vary during this time period, the facility may limit its evaluation of the phantom image to the fiber/speck/mass scores. If the facility follows this recommendation and the scores fall below the minimum requirement, the facility must cease performing mammography until the problem has been corrected. 21 C.F.R. 900.12(e)(8)(ii)(A).

Key Words:

Daily Processor QC Tests