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7.4.3. Spatial resolution test (CR and scanning systems)7.4.3.1. ScopeBlurring of the digital mammogram can impair the detectability of key structures within the breast. Themedical physicist will perform a sophisticated resolution test when the system is commissioned and annuallythereafter. For some types of digital mammography system, spatial resolution is unlikely to vary significantlybetween these tests. For systems that incorporate mechanical scanning operations during image acquisition(including CR systems), there is greater potential for the spatial resolution to change. If the equipment manufacturerprovides an MTF or spatial resolution test for the radiographer, this could be performed. Otherwise, theradiographer should consult the medical physicist to determine whether a suitable alternative approach is availablefor the system. Since this test is a constancy check, a measurement of effective resolution may be taken with the testobject on the breast support plate (detector changes only) or 4.5 cm above the breast support plate (completesystem).— Objective: To verify that spatial resolution has not deteriorated.— Frequency: Quarterly and after service of system components (scanning mechanism or CR plate reader) thatcould affect resolution.7.4.3.2. Methodology(1) Follow the instructions provided for the manufacturer’s test or for the test provided by the on-site medicalphysicist.(2) Record the test outcome on the monthly, quarterly and semi-annual checklist (Chart 2 in Annex I).7.4.3.3. Recommendations and corrective actions(1) If the measured resolution is below the baseline value, the test should be repeated; if there is still a problem,the unit should be serviced.76
7.5. SEMI-ANNUAL TESTS7.5.1. Computed radiography plate sensitivity matching and plate artefacts7.5.1.1. Scope— Objective: To confirm uniformity in the sensitivity of the CR plates used in mammography; to determine thepresence of plate related artefacts.— Minimum frequency: Semi-annually and after service to the CR reader that might affect its efficiency.7.5.1.2. Instrumentation(1) All plates used routinely in the mammography service.(2) Slab of PMMA with uniform thickness, preferably large enough to cover the entire image receptor, such asthat used for the weekly tests described in Section 7.2.3.7.5.1.3. Methodology(1) Select all plates to be evaluated.(2) For each plate, record the plate number and the condition of the cassette latches on the plate sensitivitymatching and plate artefacts chart (Chart 14 in Annex I).(3) Place the PMMA slab on the breast support of the mammography unit, ensuring that the AEC sensors arecovered. It is also necessary to ensure that the sensors are under the central part of the slab.(4) The exposure should preferably be carried out with the AEC. If the equipment does not have an AEC, selectthe technique factors manually (and use the same for all cassettes). These factors should be those clinicallyused to obtain images of a breast corresponding to the test object. Make the exposure and record the factors(AEC mode and settings, anode, filter, kV, mAs) used to make the exposure of each cassette on the datacollection sheet.(5) Process the plate after a constant time delay (say, 30 seconds), to minimize the impact of latent image fading,using the same menu choices and image processing for each plate (see Table 6).(6) Record the EI and mAs used for each cassette. Note the result on Chart 14 in Annex I.(7) Repeat steps 4 through 6 for all plates.(8) Calculate the mean value of the EI and mAs for all plates of the same size.(9) For each plate, determine the difference and the percentage difference between the mAs for that plate and therelevant mean value.(10) For each plate, determine the difference and the percentage difference between the EI for that plate and therelevant mean value.(11) If two plate sizes are used, determine the difference and percentage difference between the mean EIs for thetwo plate sizes.(12) View each image on the acquisition workstation and inspect (using a narrow window setting, as advised bythe medical physicist) for significant artefacts (signs of scratches, scrapes, dents, etc.).(13) Record the presence or absence of significant artefacts on Chart 14 in Annex I.(14) Note the outcome of the task on the monthly, quarterly and semi-annual checklist (Chart 2 in Annex I).7.5.1.4. Interpretation of results and conclusionsThe tolerances for the exposure index for CR plates are given in Table 9. In addition to the specific tolerancesoutlined in Table 9:(1) There should be no significant artefacts due to damage to or deterioration of individual plates.(2) Typically, the mAs used for a particular plate should be within ±5% of the mean value for plates of the samesize.77
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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
Page 38 and 39: 5.2.2. Electronic versus geometric
Page 40 and 41: To allow full utilization of the di
Page 42 and 43: 5.7. ARTEFACTSWhile the incidence o
Page 44 and 45: FIG. 10. Detector crystallization.
Page 46 and 47: FIG. 13. A more subtle example of a
Page 48 and 49: FIG. 16. An example of poor collima
Page 51 and 52: 7. RADIOGRAPHER’S QUALITY CONTROL
Page 53 and 54: 7.1. DAILY TESTS7.1.1. Monitor insp
Page 55 and 56: 7.1.3. Daily flat field phantom ima
Page 57 and 58: 7.1.4. Visual inspection for artefa
Page 59 and 60: 7.1.5. Laser printer sensitometry7.
Page 61 and 62: 7.1.6. Image plate erasure (CR syst
Page 63 and 64: FIG. 19. Modified TG18-QC pattern w
Page 65 and 66: FIG. 21. Radiologist workstation wi
Page 67 and 68: 7.2.1.6. Time frame for corrective
Page 69 and 70: 7.2.3. Weekly quality control test
Page 71 and 72: Note: It is not necessary to view t
Page 73 and 74: TABLE 7. TOLERANCES FOR IMAGING WEE
Page 75 and 76: 7.2.4.4. Interpretation of results
Page 77 and 78: 7.3.1.5. Recommendations and correc
Page 79 and 80: artefacts are typically best seen w
Page 81 and 82: 7.3.3.5. Recommendations and correc
Page 83 and 84: 7.4.1.3. Methodology(1) Annotate th
Page 85 and 86: RECORD OF DIGITAL MAMMOGRAPHY REPEA
Page 87: (3) Including examinations of at le
Page 91 and 92: 8. MEDICAL PHYSICIST’S QUALITY CO
Page 93 and 94: 8.1. NOTE ON IMAGE NAMING CONVENTIO
Page 95 and 96: (16) On any randomly selected patie
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
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TABLE 22. MONITOR PERFORMANCE TOLER
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FIG. 38. Measurement of illuminatio
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8.11. LASER PRINTER8.11.1. Laser pr
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8.11.1.5. Recommendations and corre
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8.12.1.4. Interpretation of results
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iopsies are performed, a sink is of
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Appendix IISPECIFICATIONS OF TEST E
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TABLE 24. SPECIFICATIONS OF TEST EQ
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FIG. 40. Image acquired with a unif
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FIG. 43. The left hand image is par
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FIG. 45. A TG18-QC test pattern dis
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[29] ALSAGER, A., YOUNG, K.C., ODUK
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Annex IRADIOGRAPHER DATA COLLECTION
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Chart 2 — DIGITAL MAMMOGRAPHY (DM
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Chart 4 LASER PRINTER SENSITOMETRY
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Chart 6 — WEEKLY DISPLAY MONITOR
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Chart 7(b) WEEKLY QC TEST OBJECT:
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Chart 9 — SAFETY AND FUNCTION CHE
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Chart 11 — LASER PRINTER ARTEFACT
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Chart 13(a) — RECORD OF DIGITAL M
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Chart 14 — CR PLATE SENSITIVITY M
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Annex IIITHE MAMMOGRAPHY EXTRACTThe
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GLOSSARYair kerma. The energy depos
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image quality. The overall merit of
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CONTRIBUTORS TO DRAFTING AND REVIEW
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