Quality Assurance Program

Questions  Key Words/Related Topics

Citation:

900.12(d): Quality Assurance — general. Each facility shall establish and maintain a quality assurance program to ensure the safety, reliability, clarity, and accuracy of mammography services performed at the facility.

Discussion:

Question 1: Why hasn't FDA specified the protocols for performing QC tests?

Question 2: How often must the densitometer and sensitometer be calibrated?

Question 3: When performing a physics survey or equipment evaluation on a unit with multiple target/filter combinations, what tests or measurements must be performed for each combination?

Question 4: I have been following the ACR manual and have used an optical density range of 0.7-0.8 when doing my screen-film contact test. The film manufacturer recommends that I use a higher optical density. What should I use under the final regulations?

Question 5: If there are several acceptable methods for testing performance of a QC requirement and the item being tested passes by one, but not all, the methods, does the item still meet the requirement?

Question 6: A facility is using more than one type of screen-film combination. Must it perform the QC tests separately for each combination used?

Question 7: How should facilities document performance of the required QC tests to comply with the regulations?

Question 8: Our facility has multiple mammographic units and uses several different screen-film combinations. What QC tests are we required to perform?

Question 1: Why hasn't FDA specified the protocols for performing QC tests?

In the final regulations, FDA has focused primarily on the performance aspects of the quality control testing, in contrast to the interim regulations, which included a complete set of procedures through referencing the ACR manuals. As a result, the agency has refrained from providing extensive detailed requirements or descriptions of test procedures.

The regulations specify the required QC test criteria and outcomes (tests to be done, frequency, and especially the action limits to be met). FDA’s approach gives facilities the flexibility to use procedures that best enable them to meet the requirements. Facilities may continue to use procedures found in current manuals as long as they are consistent with the final regulations. Besides the test methodologies, the facilities can also use their own formats or those of appropriate manuals (e.g., charts, tables) for documenting test results.

Question 2: How often must the densitometer and sensitometer be calibrated?

Answer: There are no regulatory requirements for calibrations of these devices. FDA encourages the facility to follow the manufacturer recommended calibration procedures for such devices.

Question 3: When performing a physics survey or equipment evaluation on a unit with multiple target/filter combinations, what tests or measurements must be performed for each combination?

For a unit with multiple target/filter combinations, the following tests must be performed for each clinically used target/filter combination:

• Focal spot condition (for different target materials [tracks] only)

• X-ray field/light field/image receptor/compression paddle alignment (for different target materials [tracks] only)

• Beam quality and half-value layer

• System artifacts

Question 4: I have been following the ACR manual and have used an optical density range of 0.7-0.8 when doing my screen-film contact test. The film manufacturer recommends that I use a higher optical density. What should I use under the final regulations?

The final regulations do not reference a specific manual giving facilities flexibility to use procedures that best enable them to meet the requirements. In this specific case, the facility may follow the manufacturer’s recommendation, their medical physicist’s recommendation, or an appropriate manual in performing the screen-film contact test or any other QC test.

Question 5: If there are several acceptable methods for testing performance of a QC requirement and the item being tested passes by one, but not all, the methods, does the item still meet the requirement?

Yes, as long as the required QC test criteria and outcomes (tests to be done and especially the action limits to be met) are satisfied.

Question 6: A facility is using more than one type of screen-film combination. Must it perform the QC tests separately for each combination used?

It depends. For the majority of the QC tests, the type of screen-film combination used in the test is irrelevant to the test outcome. However, for the following QC tests, the regulations spell out specific requirements:

1. System Resolution - must be measured for each screen-film combination used at the facility with its corresponding unit(s).

2. Phantom Image and Dose – each of these must be conducted for each screen-film combination clinically used for the standard breast.

Note that the phantom image test applies to both the weekly QC and the annual test conducted by the medical physicist as part of the survey report. If only one combination is routinely used for the standard breast and the other combination is used for non-routine examinations of the standard breast, FDA recommends that the dose and phantom image QC tests also be conducted for the other combination, because the outcome of both tests is heavily influenced by the film-screen combination used.

Note that testing for the uniformity of screen speed must be conducted for all screens and cassettes respectively. Hence, by default, it includes all types of screens used, but this does not preclude performing this test with only one type of film. System artifacts must be performed for each cassette size.

Question 7: How should facilities document performance of the required QC tests to comply with the regulations?

Performance of the required QC tests must include clear and legible documentation. The documentation must include test results and the dates when the tests were performed. For each test result that falls outside the action limits, the documentation must also include the date and the corrective actions taken and their results. The data and results should be properly charted or tabulated. Facilities may consult any appropriate quality control manual for examples of charts and tables or establish their own format for documenting the test data and the results

Question 8: Our facility has multiple mammographic units and uses several different screen-film combinations. What QC tests are we required to perform?

The required QC tests are summarized in the following table.

Table: QC Tests* Required for Facilities Using Multiple Units & Screen-Film Combinations

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* This table does not cover other required QC tests that are independent of the x-ray unit or screen-film combination (e.g., the daily processor QC, the fixer retention, and repeat analysis), or additional tests that are required for units with multiple targets and filters.

** In this table, "All units" refers to those that are used clinically.

*** The standard breast referenced in this table is defined in the regulations as "a 4.2 centimeter (cm) thick compressed breast consisting of 50 percent glandular and 50 percent adipose tissue."

Key Words:

Quality Assurance

Quality Assurance Program

Related Topics

Equipment Evaluations

Medical Physicist Annual Survey

Annual Equipment Quality Control Tests

Semiannual Equipment Quality Control Tests

System Resolution Annual Quality Control Test

Weekly Equipment Quality Control Tests