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8.12. IMAGE QUALITY8.12.1. Evaluation of image quality8.12.1.1. ScopeIt is recognized that no phantom is currently available that truly mimics the complex problem of imaging thebreast. Nevertheless, it is possible to assess some key features of mammography quality by imaging a subjectivebreast phantom. This, for example, is the basis of image quality assessment in the IAEA QA programme for screenfilm mammography [34].In digital mammography, it is useful to perform routine imaging of such a phantom to confirm that there havebeen no substantial changes in imaging performance from the baseline. No particular phantom can berecommended at this time. Instead, the facility should use whatever nationally or internationally recommendedphantom is currently used for its screen film or digital mammography QC programmes.— Objective: To establish a baseline level of subjective image quality; to ensure that the overall image qualityhas not degraded from baseline performance levels.— Minimum frequency: At commissioning, annually and after changes.8.12.1.2. Instrumentation(1) Breast phantom containing structures mimicking those found in the breast.(2) Magnifying lens (4× to 5× magnification).8.12.1.3. Methodology(1) Place the phantom on the breast support positioned flush with the chest wall and centred laterally.(2) Lower the compression paddle to apply a compression force typically used clinically (e.g. 80 N). 34(3) If there is a separate AEC sensor, confirm that it is correctly located under the phantom.(4) Select the technique factors that are used in the clinical practice for a breast having characteristics equivalentto those of the phantom. Normally this is achieved by using the automatic exposure mode. Otherwise, selectthe appropriate target, filter, kV, grid, density control position and operation mode (semiautomatic orautomatic).(5) Make an exposure.(6) On the phantom image quality chart (Chart 18 in Annex II), record the exposure factors, the exposureindicator for CR systems and technique used.(7) Process the image using the algorithms that would be used clinically.(8) Compare this image with the baseline image obtained on this system. Determine if there are artefacts thatcould be confused with any of the phantom details. With the magnifying lens, carefully examine the image fornon-uniform areas, dirt or dust, lines (if the grid is used), processing artefacts or any other type of artefact.(9) If desired, evaluate the image according to the evaluation method provided by the manufacturer. 35 Note theresults on the data collection sheet.(10) Investigate the causes of any artefacts.34The actual force should be similar to the typical value used clinically, but the same value should be used for all testing. Notethat in some systems and in some modes of operation, the compressed breast thickness is utilized in an automated algorithm todetermine the technique factors; this thickness is, in turn, dependent on the degree of compression applied.35A description of how this is done for the ACR accreditation phantom is provided in the IAEA publication Quality AssuranceProgramme for Screen Film Mammography (IAEA Human Health Series No. 2) [34].134
8.12.1.4. Interpretation of results and conclusionsTolerances:(1) There should be no significant degradation of image quality or changes in exposure factors, or in the exposureindicator for CR systems, from the baseline image.(2) The image quality assessment of the phantom should yield results that are as good as, or better than, thoseexpected with high quality screen film mammography as tested with the same phantom.8.12.1.5. Recommendations and corrective actionsIf the image quality deteriorates over time, it will be necessary to carry out other investigations (e.g. kV, AEC,display, processing algorithms) to determine the source of the change. 3636Due to the subjective component associated with the observer, it is recommended that the test always be performed by thesame person, using the same criteria and viewing conditions.135
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X raysdel matrixCs scintillatorLine
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QUALITY ASSURANCE PROGRAMMEFOR DIGI
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IAEA HUMAN HEALTH SERIES No. 17QUAL
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FOREWORDThe application of radiatio
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An effective QA programme is necess
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The Integrating the Healthcare Ente
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technology. Systems containing othe
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X raysTop electrodea-Se layerCharge
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dose received by inhomogeneous real
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2.3.8.1. Soft copy displayFlat pane
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3. ELEMENTS OF HIGH QUALITY MAMMOGR
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— The ability to mask edges of ma
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Disposal orsaleNew facility(start h
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4.2.3. Radiographer (mammography te
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5.2.2. Electronic versus geometric
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To allow full utilization of the di
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5.7. ARTEFACTSWhile the incidence o
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FIG. 10. Detector crystallization.
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FIG. 13. A more subtle example of a
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FIG. 16. An example of poor collima
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7. RADIOGRAPHER’S QUALITY CONTROL
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7.1. DAILY TESTS7.1.1. Monitor insp
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7.1.3. Daily flat field phantom ima
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7.1.4. Visual inspection for artefa
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7.1.5. Laser printer sensitometry7.
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7.1.6. Image plate erasure (CR syst
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FIG. 19. Modified TG18-QC pattern w
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FIG. 21. Radiologist workstation wi
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7.2.1.6. Time frame for corrective
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7.2.3. Weekly quality control test
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Note: It is not necessary to view t
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TABLE 7. TOLERANCES FOR IMAGING WEE
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7.2.4.4. Interpretation of results
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7.3.1.5. Recommendations and correc
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artefacts are typically best seen w
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7.3.3.5. Recommendations and correc
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7.4.1.3. Methodology(1) Annotate th
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RECORD OF DIGITAL MAMMOGRAPHY REPEA
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(3) Including examinations of at le
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7.5. SEMI-ANNUAL TESTS7.5.1. Comput
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8. MEDICAL PHYSICIST’S QUALITY CO
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8.1. NOTE ON IMAGE NAMING CONVENTIO
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Page 97 and 98: FIG. 30. Positioning of bathroom sc
Page 99 and 100: (6) The target, filter, kV, grid, d
Page 101 and 102: (2) Stack the 20 and 25 mm PMMA sla
Page 103 and 104: TABLE 13. ACCEPTABLE AND ACHIEVABLE
Page 105 and 106: 8.5. DETECTOR PERFORMANCE8.5.1. Bas
Page 107 and 108: 8.5.2. Detector response and noise8
Page 109 and 110: the service engineer responsible fo
Page 111 and 112: (13) Using the annotation tool on t
Page 113 and 114: Breast supportPMMA slabBreast suppo
Page 115 and 116: (10) Place the thinner test object
Page 117 and 118: 8.6. EVALUATION OF SYSTEM RESOLUTIO
Page 119 and 120: TABLE 17. ACCEPTABLE FREQUENCIES AT
Page 121 and 122: 8.7. X RAY EQUIPMENT CHARACTERISTIC
Page 123 and 124: 8.7.2. Incident air kerma at the en
Page 125 and 126: 8.8. DOSIMETRY8.8.1. Mean glandular
Page 127 and 128: TABLE 21. ACCEPTABLE AND ACHIEVABLE
Page 129 and 130: FIG. 34. Suggested layout for ruler
Page 131 and 132: 8.10. IMAGE DISPLAY QUALITYThe accu
Page 133 and 134: FIG. 35. Modified TG18-QC test patt
Page 135 and 136: 8.10.1.5. Interpretation of results
Page 137 and 138: 8.10.2. Monitor luminance response
Page 139 and 140: TABLE 22. MONITOR PERFORMANCE TOLER
Page 141 and 142: FIG. 38. Measurement of illuminatio
Page 143 and 144: 8.11. LASER PRINTER8.11.1. Laser pr
Page 145: 8.11.1.5. Recommendations and corre
Page 150 and 151: iopsies are performed, a sink is of
Page 152 and 153: Appendix IISPECIFICATIONS OF TEST E
Page 154 and 155: TABLE 24. SPECIFICATIONS OF TEST EQ
Page 156 and 157: FIG. 40. Image acquired with a unif
Page 158 and 159: FIG. 43. The left hand image is par
Page 160 and 161: FIG. 45. A TG18-QC test pattern dis
Page 162 and 163: [29] ALSAGER, A., YOUNG, K.C., ODUK
Page 165 and 166: Annex IRADIOGRAPHER DATA COLLECTION
Page 167 and 168: Chart 2 — DIGITAL MAMMOGRAPHY (DM
Page 169 and 170: Chart 4 LASER PRINTER SENSITOMETRY
Page 171 and 172: Chart 6 — WEEKLY DISPLAY MONITOR
Page 173 and 174: Chart 7(b) WEEKLY QC TEST OBJECT:
Page 175 and 176: Chart 9 — SAFETY AND FUNCTION CHE
Page 177 and 178: Chart 11 — LASER PRINTER ARTEFACT
Page 179 and 180: Chart 13(a) — RECORD OF DIGITAL M
Page 181 and 182: Chart 14 — CR PLATE SENSITIVITY M
Page 183 and 184: Annex IIITHE MAMMOGRAPHY EXTRACTThe
Page 185 and 186: GLOSSARYair kerma. The energy depos
Page 187 and 188: image quality. The overall merit of
Page 189: CONTRIBUTORS TO DRAFTING AND REVIEW
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