iaea human health series publications - SEDIM

6. OUTLINE OF QUALITY CONTROL TESTSQC tests are intended to verify the stability of the operation of the equipment or elements used to acquire themammogram. The tests have been classified into two types: essential and desirable, with respect to their importancein influencing image quality and dose. The performance of the first category of tests is considered indispensable;however, it is recommended that the tests in the second category also be carried out if adequate human resourcesand equipment can be made available.Essential refers to tests that:Test Priority— Must be done in a facility; or— The minimum frequency at which the tests must be performed.Desirable describes:— The test procedures that should be performed if feasible; or— The frequency at which the tests should be performed if feasible.Many of the tests need to be performed very frequently (weekly and daily). Therefore, it is recommended thatthese tests be performed by local personnel who are present daily in the facility (technical personnel, normallyradiographers). In the majority of cases, the lower frequency (and more specialized) tests have been assigned tomedical physicists. Tolerance values for the tests are indicated. These, too, are classified into two categories:acceptable and achievable. In some cases, only the acceptable level has been defined.Performance StandardsAcceptable indicates that performance must be within these tolerances;if it is not, the equipment should not be used.Achievable indicates the level of performance that should be attained under favourable circumstances;this is the level at which a facility should work if it is feasible.A facility should strive to ensure that equipment operates at the achievable level of performance, as this willproduce the highest image quality and the most appropriate dose performance. It is recognized, however, thatlimited resources, uncorrectable environmental factors and other factors may occasionally prevent the achievablelevels from being obtained. In no case should the facility continue to perform mammography if the equipment doesnot meet the acceptable standard of operation, because below this level the value of the procedure and/or its safetyis considered unacceptable. Each test in the QC programme has a specified tolerance level for achievable andacceptable results, as applicable. Should the results of a test fall outside the specified tolerance, the test shouldusually be repeated to confirm the result before action is taken.Suitable minimum specifications for test equipment are provided in Appendix II.Table 4 in Section 7 of this publication lists all the QC tests to be carried out by the radiographer; those QCtests to be carried out by the medical physicist are listed in Table 10 in Section 8 of this publication. In some cases,either person could perform a particular test, so the tests are listed in both tables. In such cases, a decision must bemade as to who will actually perform the test, and that person should consistently carry out the test thereafter.37