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U.S. Department of Health and Human Services

Radiation-Emitting Products

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Daily Processor QC Tests

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Conducting the daily processor QC tests when the sensitometer is not available

This alternative standard was approved on October 18, 1999 and was made retroactive to April 28, 1999. The alternative to sensitometric-densitometric testing of processor performance can be used for a period of up to two weeks when the facility’s sensitometer is unavailable. This alternative is based on evaluating a phantom image through measurements described in 21 CFR 900.12(e)(1) and (2).

The final regulation and its alternative standard are stated below:

21 CFR 900.12(e)(1) and (2) states that:

(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 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.

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

(i)  The optical density of the film at the center of an image of a standard FDA-accepted phantom shall be at least 1.20 when exposed under a typical clinical condition.

(ii)  The optical density of the film at the center of the phantom image shall not change by more than +/- 0.20 from the established operating level.

(iii)  The phantom image shall achieve at least the minimum score established by the accreditation body and accepted by FDA in accordance with Sec. 900.3(d) or Sec. 900.4(a)(8).

(iv)  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 +/- 0.05 from the established operating level.

When using the alternative test, processor performance is considered satisfactory if:

1.  The optical density of the film at the center of an image of a standard FDA-accepted phantom is at least 1.20 when exposed under typical clinical conditions.

2.  The optical density of the film at the center of the phantom image changes no more than +/- 0.20 from the established operating level.

3.  The density difference between the background of the phantom and an added test object, used to assess image contrast, is measured and does not vary by more than +/-0.05 from the established operating level.

In addition:

4.  To evaluate base + fog, an additional measurement of density must be made either of a shielded portion of the phantom image film or of an unexposed film. In accordance with 21 CFR 900.12(e)(1)(i), the base plus fog density must be within + 0.03 of the established operating level.

This alternative test must be conducted "each day clinical films are processed, but before processing of clinical films." All results must be recorded and charted. If processor performance fails to meet any part of the alternative test, the problem must be corrected before processing is resumed.