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Laser printers used in mammography can print one or more images on a sheet of transparent film (typically,18 cm × 24 cm or 24 cm × 30 cm). These films are placed on a viewbox in a darkened room for viewing. A viewingsystem and reading room designed for film mammography are normally suitable for interpretation of hard copydigital mammograms.Typically, transparent laser films do not have the same maximum optical density capability as mammographyfilms. The dynamic range of laser films is from an optical density of approximately 0.20 up to around 3.2,depending on the film type. It is recommended that the laser imager characteristic curve be in conformity with theDICOM Grayscale Standard Display Function (GSDF).QC procedures are based on printing out test patterns to check a series of parameters (density uniformity,greyscale response function, spatial resolution, geometrical distortion, image quality). Testing by the radiographeris described in Section 7.4 and testing by the physicist, in Section 8.11.To test laser printers, it is recommended that test images in the same format as the digital mammograms besent to the printer from the digital mammography system. In this way, the lookup table (LUT) and any other imageprocessing that will be applied to clinical images will also be applied to the test images. In some cases, this is notpossible and test images are sent from the printer itself. One must be aware that in some facilities, the same printeris used to print out images from different types of examination (e.g. breast, chest, bones, ultrasound, computedtomography (CT), magnetic resonance imaging (MRI)). Each examination type or modality has a defined LUT.Therefore, the correct LUT has to be selected before mammograms or the different test patterns are printed. TheLUT has to be established in agreement with the mammography system manufacturer. For this reason, it is alsoimportant to check which LUT is automatically selected by the printer when the images are sent to print from themammography system.As with conventional radiographic films, laser films have to be stored in appropriate conditions before andafter processing. As heat processed film is damaged by strong sunlight and high temperatures, exposing it to directsunlight or leaving it on a viewing screen for a long time should be avoided.16
3. ELEMENTS OF HIGH QUALITY MAMMOGRAPHY3.1. PERSONNELThere are many elements that contribute to the mammography process. The experience of personnel directlyand indirectly involved in the process is crucial to the final outcome. In this respect it is essential that:— The mammography images are acquired by experienced radiographers trained specifically in mammography.— The images are interpreted by an appropriately trained and experienced radiologist.— A medical physicist is available as a consultant to the facility. This may be on a full time or part time basis,according to the QA and radiation protection needs of the facility. (See Section 4.2.4 and appendix I ofRef. [34] for the specific requirements that a medical physicist should meet.)— Well trained and experienced personnel service and maintain the mammography equipment.— There is training on the specific mammographic unit, usually provided by the manufacturer as part of thepurchase package.Access to staff with training in information technology is highly desirable [35].3.2. EQUIPMENT3.2.1. Digital mammography X ray unitThe digital mammography X ray unit must be specifically designed for mammography and include thefollowing key features:— An X ray tube with a nominal focal spot of 0.3 mm [36].— A magnification stand and a second, smaller focal spot of nominal size (≤0.15 mm), if magnificationmammography is performed (this capability should be present on systems that are used for diagnosticmammography and not exclusively for screening).— A beryllium exit window.— Appropriate X ray target material and beam filter(s) for the X ray target. (For examples of target–filtercombinations in use at the time of writing, see Table 3; the latest version of this table will be posted on theIAEA web site at: http://humanhealth.iaea.org.— A motorized compression device.— Readout of compression thickness and force.—AEC.— Scatter rejection capability.— A focus image distance greater than 60 cm.— A detector with dimensions large enough to image most compressed breasts without the need for multipleexposures. Typically, this may mean larger than 24 cm × 26 cm, although there may be geographic variationsin this requirement.— An acquisition workstation with a monitor of sufficient resolution (3 MP is recommended) to allow theradiographer to ensure the quality of the mammography images. This is particularly important when hardcopy images are used for clinical diagnoses.The room in which the digital mammography unit is sited should have stable temperature and humidity forsatisfactory operation. This will require appropriate air conditioning. More complete details on siting amammography unit are provided in Appendix I.17
Page 1 and 2: X raysdel matrixCs scintillatorLine
Page 3 and 4: QUALITY ASSURANCE PROGRAMMEFOR DIGI
Page 5 and 6: IAEA HUMAN HEALTH SERIES No. 17QUAL
Page 7 and 8: FOREWORDThe application of radiatio
Page 14: An effective QA programme is necess
Page 17 and 18: The Integrating the Healthcare Ente
Page 21 and 22: technology. Systems containing othe
Page 23 and 24: X raysTop electrodea-Se layerCharge
Page 25 and 26: dose received by inhomogeneous real
Page 27: 2.3.8.1. Soft copy displayFlat pane
Page 31: — The ability to mask edges of ma
Page 34 and 35: Disposal orsaleNew facility(start h
Page 36 and 37: 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
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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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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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