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wheret 1 and t 2 are the thicknesses (in mm) of the filters used;M 0 is the average value of readings measured in steps 6 and 9 without any added filter;M 1 and M 2 are the readings measured in steps 7 and 8 that are respectively just above and just below 50%of M 0 .(2) Note the calculated HVL on Chart 10 in Annex II.8.7.1.5. Interpretation of results and conclusionsTolerance:Acceptable: kV/100 + 0.03 ≤ HVL ≤ kV/100 + CwhereC = 0.12 for Mo/Mo;0.19 for Mo/Rh;0.22 for Rh/Rh;0.30 for W/Rh;0.32 for W/Ag;0.25 for W/Al;and kV is the measured value for the nominal kV selected.On Chart 10 in Annex II, record whether the value of the HVL is acceptable. If this tolerance is met, it isgenerally the case that regulatory requirements for total beam filtration without the compression paddle willalso be satisfied.8.7.1.6. Recommendations and corrective actionsIf the HVL is very low or very high, investigative action should be undertaken. This may include ameasurement of the kV to confirm that the tube potential is properly calibrated. Methods are described in Ref. [34].8.7.1.7. Time frame for corrective actionImmediately: Corrective action should be taken until the problem is solved.110
8.7.2. Incident air kerma at the entrance surface of PMMA slabs8.7.2.1. Scope— Objective: To estimate the incident kerma in air (without backscatter) at the position corresponding to theentrance surface of PMMA of thicknesses of 20, 45 and 70 mm 23 . The measurement can be done at aconvenient distance from the X ray source and then calculated for the locations of the entrance surfaces usingan inverse square law correction.— References [8, 48, 60, 64, 65].— Minimum frequency: Annually and after change of, or maintenance to, the X ray tube, tube housing and/orcollimation system.8.7.2.2. Instrumentation(1) Dosimeter appropriate for mammography (see Appendix II).(2) Exposure technique data from the AEC test (see Section 8.4.2 for target–filter combination, kV and mAs AEC )for the PMMA slabs with thicknesses of 20, 45 and 70 mm.(3) Metal plate to shield the detector from X rays (e.g. 1 mm steel, 5 mm aluminium or >0.1 mm lead), largeenough to cover the active area of the detector.(4) Tape measure.(5) Thermometer.(6) Barometer.8.7.2.3. MethodologyThe incident air kerma without backscatter is measured using the same exposure factors selected to expose aphantom equivalent to three thicknesses of PMMA representing breasts of different attenuation. The incident kermain air at the entrance surface of the PMMA slab(s) is determined from: (a) the mAs value used to expose the PMMAslab with the target–filter–kV combination used in Section 8.4.2 (mAs AEC ); (b) the measured incident kerma in airfor the given mAs AEC ; and (c) the measured distance from the focus of the X ray tube to the breast support table.(1) Determine the distance, d T , from the focus of the X ray tube to the breast support table and record it in thekerma and dose chart (Chart 11 in Annex II). 24 This can be determined using the manufacturer’s specificationsor by measurement, if necessary.(2) Place the metal shield on the breast support table to protect the digital detector from excessive exposure. Donot scratch the table.(3) Attach the dosimeter to the lower surface of the compression paddle. The dosimeter should be centredlaterally in the beam, approximately 40 mm into the radiation field from the chest wall edge of the beam. Setthe height of the compression paddle so that the centre of the active volume of the dosimeter (themeasurement point) is 45 mm above the breast support table. 2523The measurement is made without the PMMA, because it should be done without scattered radiation. Note that the originalMonte Carlo modelling [63] incorporated a correction to the incident air kerma that would have been present for a thicker breast whoseattenuation corresponds to these PMMA thicknesses. Therefore the entrance kerma to the PMMA is evaluated, rather than the kerma tothe entrance of the breast.24This is difficult to measure accurately with a tape measure, and it may be best to obtain the distance from the manufacturer.This measurement need not be repeated unless there are changes to the mechanical assembly that would affect this distance.25The dosimeter is placed at the same height as the top surface of a 45 mm PMMA slab rather than at the height of theequivalent breast thickness because the inverse square law correction to the surface of the breast is already incorporated in theconversion factors used in Table 18.111
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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
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 and 88: (3) Including examinations of at le
Page 89 and 90: 7.5. SEMI-ANNUAL TESTS7.5.1. Comput
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: 8.7. X RAY EQUIPMENT CHARACTERISTIC
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 and 146: 8.11.1.5. Recommendations and corre
Page 147: 8.12.1.4. Interpretation of results
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
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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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