• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

Radiation-Emitting Products

  • Print
  • Share
  • E-mail

If a unit is used clinically at combinations of kVp and filtration that include thicknesses outside the 2 to 6 cm range, must it meet the AEC performance requirements at the thicknesses where it operates and must it be tested at those technique factors under the annual quality control requirements? What about AEC performance testing during a mammography equipment evaluation?

Policy Guidance Help System logo

The regulations in 900.12(e)(5)(i) require that an x-ray unit pass an annual test for AEC performance using 2, 4, and 6 centimeter thicknesses of a homogeneous material. If a unit is used clinically at combinations of kVp and filtration that include thicknesses outside the 2 to 6 cm range, must it meet the AEC performance requirements at the thicknesses where it operates and must it be tested at those technique factors under the annual quality control requirements? What about AEC performance testing during a mammography equipment evaluation?

During the annual physics survey, the unit is not required to meet the AEC performance action limit outside the 2 to 6 cm range and the medical physicist is not required to test the AEC using thicknesses outside this range. However, we recommend that in addition to the required testing in the 2 to 6 cm range, the unit also be tested at all clinically used thicknesses outside this range and that the action limits specified in the regulations be applied to the extended test. If the unit cannot meet these action limits outside the 2 to 6 cm range, FDA recommends that a technique chart be developed showing appropriate technique factors (kVp, AEC mode, target/filter, and density control setting) for the different breast thicknesses and compositions so that optical densities (OD) within +/- 0.15 OD of the MOD under AEC testing conditions can be produced.

During the mammography equipment evaluation (as defined in 900.12(e)(10)), the medical physicist must evaluate the AEC in all clinically used configurations (See Question 4). Section 900.12(e)(10) requires that the AEC meet the requirements of 900.12(b) and (e). Under 900.12(b)(10), the AEC is required to be "operable" under "configurations provided." The term "operable," means the AEC must meet the performance requirements of 900.12(e)(5)(i) within the 2 to 6 cm range. FDA also recommends that in addition to the required testing in the 2 to 6 cm range, the unit also be tested in all configurations at all clinically used thicknesses outside this range and that the action limits specified in the regulations be applied to the extended test. If the unit cannot meet these action limits outside the 2 to 6 cm range, FDA recommends that a technique chart be developed showing appropriate technique factors (kVp, AEC mode, target/filter, and density control setting) for the different breast thicknesses and compositions so that optical densities (OD) within +/- 0.15 OD of the MOD under AEC testing conditions can be produced.

Back to Automatic Exposure Control (AEC) Performance Testing