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U.S. Department of Health and Human Services

Radiation-Emitting Products

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If the optical density (OD) for the weekly phantom test falls below 1.20 (and/or changes by more than +/- 0.20 from the established operating level), must the unit be recalibrated or can we adjust the density setting to obtain a 1.20 OD?

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If the OD at the center of the phantom image falls below the required minimum of 1.20 (and/or changes by more than +/- 0.20 from the established operating level), the facility should follow pathway A, B, or C; below, based on the situation at the facility:

  1. If the film is of a different type (e.g., switch from Min-R 2000 to Min-R E) from the previous week’s passing test, the facility should establish new phantom QC operating levels.

  2. If the film emulsion batch is unchanged from the previous week’s passing test:

  1. Ensure that the phantom is exposed using typical clinical conditions and that the position of the phantom and, where appropriate, the position of the AEC detector have not changed from that used for prior images.

  2. Reevaluate the daily processor performance and make sure the processor is properly optimized according to the film manufacturer’s specifications.

  3. If the facility has been tracking mAs, check the function of the mammography unit by comparing the mammography unit’s current mAs output with values obtained for previous phantom images. If the mAs has changed by more than 15%, and the facility has been using the same kVp, the same mammography unit density setting, and the processor is operating within its action limits, then the medical physicist should be called to check the entire imaging chain, including the mammography unit. If the mAs has not changed by more than 15%, then proceed with step 4.

 If the facility has not been tracking mAs, the facility should consult with its medical physicist for what to do next.

  1. If no problems are found in steps 2 and 3, adjust the density control setting to obtain an optical density of at least 1.20 at the center of the phantom image (or obtain an optical density within +/- 0.20 of the established operating level).

  2. Adjust the density control setting used clinically to be consistent with the changes made in step 4.

  1. If the film is of the same type but of a different emulsion batch from the previous week’s passing test, the facility should follow the steps as described in B 1 through 5.

If the optical density again falls below 1.20 (and/or changes by more than +/- 0.20 from the established operating level) the next time the weekly phantom test is performed, the facility should follow the appropriate pathway (based on the film emulsion used) from the following three options:

  1. If film of a different type (e.g., switch from Min-R 2000 to Min-R E) is used, the facility should establish new phantom QC operating levels.

  2. If film of the same emulsion batch is used (assuming the same kVp and mammography unit density settings are used, and the processor is operating within its action limits), the facility should consult with its physicist and check the entire imaging chain before performing mammograms.

  3. If film of the same type (but not of the same emulsion batch) is used, the facility should repeat steps B 1 through 5.

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