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esolution pattern. A tool for determining the limiting spatial resolution of an imaging system. It is composed ofgroups of several highly X ray attenuating strips spaced by an equal width of non-attenuating material, eachstrip and adjacent spacer being referred to as a ‘line pair’. The reciprocal of the total width (in millimetres)occupied by the line and the space determines the number of line pairs per millimetre (lp/mm) for that group.Each group of strips is smaller than the previous group; that is, it consists of more line pairs per millimetre.The last group in which each bar is visible as a distinct line indicates the limiting spatial resolution (in lp/mm)of the system.screening mammography. X ray breast examination of asymptomatic women in an attempt to detect breast cancerwhen it is small, nonpalpable and confined to the breast.source to image distance (SID). The shortest distance between the point of X ray production (focal spot) and theimage receptor (detector).spatial frequency. A spatial pattern such as an image can be represented as the summation of a set of spatialsinusoidal functions of appropriate amplitudes, each sinusoid covering a specific distance (e.g. millimetres)per cycle. The spatial frequency is the reciprocal of that distance and is specified in cycles/millimetre.spatial resolution. The fineness of spatial detail that an imaging system can demonstrate. This can be measuredfrom the image of a resolution pattern in terms of the number of line pairs per millimetre (see resolutionpattern). Spatial resolution can be affected by the size of the X ray source, geometric magnification, blurringof signal in the X ray detector, the del size and pitch, and the pixel size. The limit imposed by data samplingis that the maximum spatial resolution (Nyquist frequency — line pairs per millimetre or lp/mm) is equal toone half the number of pixels/mm (i.e. if the sampling frequency is 5 pixels/mm, the maximum spatialresolution is 2.5 lp/mm). Spatial resolution depends on the sampling frequency for cassette based systems andthe detector element size for cassette-less systems. With TFT based detectors, the actual spatial resolution isnear the Nyquist frequency. With PSP based CR systems, the spatial resolution is less than the Nyquistfrequency to the light spread from the PSP plate during image extraction. Unlike screen film systems, there islittle correlation between exposure level and spatial resolution.standard breast. A 53 mm thick compressed breast consisting of 29% fibroglandular and 71% adipose tissue usedas the ‘average’ breast for dosimetry calculations. This may be represented by 45 mm of PMMA, a thicknessthat attenuates approximately the same amount as the standard breast.structured noise. A background pattern in a radiograph that often adds visual clutter and degrades or masks thedetection of a lesion. In a clinical image, normal anatomy can provide structured noise. In phantom images,structured noise is typically the result of systematic artefacts such as roller marks in screen film images, gridlines or poor flat fielding of digital images.system spatial resolution. Resolution of the whole system and not just one component, such as the focal spot orgeometric resolution or the detector resolution.tolerance values. Values that express the range over which the parameter is allowed to vary before the item is nolonger considered to be operating within limits. These ranges are classified into two categories: ‘achievable’and ‘acceptable’.viewbox. A device providing a relatively uniform surface luminance for viewing mammographic films.Mammographic viewboxes should have a luminance level of at least 3000 cd/m 2 (nit).176
CONTRIBUTORS TO DRAFTING AND REVIEWBloomquist, A.Bosmans, H.Burch, A.Chevalier, M.Daros, K.Gennaro, G.Heggie, J.Jong, R.Mawdsley, G.McLean, I.D.Mora, P.Pongnapang, N.Rajapakshe, R.Rehani, M.Rickard, M.Yaffe, M.Young, K.Sunnybrook Health Sciences Centre, University of Toronto, CanadaUniversity Hospital Leuven, BelgiumBreast Test Wales, United KingdomComplutense University of Madrid, SpainFederal University of São Paulo, BrazilOncological Institute of Veneto, ItalySt Vincent’s Hospital, AustraliaSunnybrook Health Sciences Centre, University of Toronto, CanadaSunnybrook Health Sciences Centre, University of Toronto, CanadaInternational Atomic Energy AgencyUniversity of Costa Rica, Costa RicaMahidol University, ThailandBC Cancer Agency, CanadaInternational Atomic Energy AgencySydney Breast Clinic, AustraliaSunnybrook Health Sciences Centre, University of Toronto, CanadaRoyal Surrey County Hospital, United KingdomConsultants MeetingsVienna, Austria: 2–6 July 2007, 21–24 April 2008, 4–7 August 2009177
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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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(16) On any randomly selected patie
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FIG. 30. Positioning of bathroom sc
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(6) The target, filter, kV, grid, d
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(2) Stack the 20 and 25 mm PMMA sla
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TABLE 13. ACCEPTABLE AND ACHIEVABLE
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8.5. DETECTOR PERFORMANCE8.5.1. Bas
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8.5.2. Detector response and noise8
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the service engineer responsible fo
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(13) Using the annotation tool on t
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Breast supportPMMA slabBreast suppo
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(10) Place the thinner test object
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8.6. EVALUATION OF SYSTEM RESOLUTIO
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TABLE 17. ACCEPTABLE FREQUENCIES AT
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8.7. X RAY EQUIPMENT CHARACTERISTIC
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8.7.2. Incident air kerma at the en
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8.8. DOSIMETRY8.8.1. Mean glandular
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TABLE 21. ACCEPTABLE AND ACHIEVABLE
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FIG. 34. Suggested layout for ruler
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8.10. IMAGE DISPLAY QUALITYThe accu
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FIG. 35. Modified TG18-QC test patt
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8.10.1.5. Interpretation of results
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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
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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: image quality. The overall merit of
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