900.12(e)(5)(i)(A)(B)(C): Annual quality control tests. Facilities with screen-film systems shall perform the following quality control tests at least annually:
(i) Automatic exposure control performance.
(A) The AEC shall be capable of maintaining film optical density within ±0.30 of the mean optical density when thickness of a homogeneous material is varied over a range of 2 to 6 cm and the kVp is varied appropriately for such thicknesses over the kVp range used clinically in the facility. If this requirement cannot be met, a technique chart shall be developed showing appropriate techniques (kVp and density control settings) for different breast thicknesses and compositions that must be used so that optical densities within ±0.30 of the average under phototimed conditions can be produced.
(B) After October 28, 2002, the AEC shall be capable of maintaining film optical density (OD) within ±0.15 of the mean optical density when thickness of a homogeneous material is varied over a range of 2 to 6 cm and the kVp is varied appropriately for such thicknesses over the kVp range used clinically in the facility.
(C) The optical density of the film in the center of the phantom image shall not be less than 1.20.
- If the AEC fails, can a facility use manual techniques until the unit is fixed? Would it require the physicist to come and recheck it or if the repairman did so would that be satisfactory?
- Do units with multiple AEC detectors have to have each detector tested individually?
- The regulations in 900.12(e)(5)(i) require that an x-ray unit pass an annual test for AEC performance over a range of 2 to 6 cm thick absorbers. If a unit is used clinically at combinations of kVp and filtration that include tissue 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?
- During the annual physics survey, must AEC performance be tested for all equipment configurations used clinically by the facility or can it be limited to the contact configuration? What action limits apply?