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Potential challenges or disadvantages associated with digital mammography include:— Higher capital costs.— The increased time required for image interpretation coupled with a need for radiologists to adjust to newimage attributes.— The need for radiologists, radiographers, clerks, etc., to adjust to new technology.— Possible increased patient dose. 2— Difficulties in comparing digital images with film mammograms.— Poorer technical performance characteristics of some digital systems compared with screen film, as expressedby their modulation transfer function (MTF), detective quantum efficiency (DQE) and signal difference tonoise ratio (SDNR).— Incompatibility between different digital systems.— Difficulty in providing images to nondigital facilities (e.g. referring physicians).— The increased complexity of technology leading to increased service costs.— The need to interface the operation of several computer systems (image viewing, patient worklist, reporting),often provided by different vendors.— Availability of suitably trained service personnel.— Equipment reliability problems (e.g. detector failures due to abnormal temperatures).— More demanding environmental requirements (e.g. properly conditioned electrical power, dust control andlighting conditions, Internet connections, ventilation and air conditioning). For example, many digital unitsrequire air conditioning to be provided 24 hours a day, 7 days a week to prevent damage to the detector.All these factors should be taken into account when any facility contemplates making the transition fromscreen film to digital mammography. In particular, the capital and maintenance costs of digital mammographyequipment are considerably higher than those of screen film systems, although there are some offsetting costsavings (no film, processing chemistry, processor maintenance or film library). This factor, combined withuncertainty concerning the clinical and other advantages of digital mammography and concerns about buying asystem that might quickly become obsolete (although the technology has now begun to stabilize), has resulted inrelatively slow uptake of this technology. Balancing these factors may mean that, in many facilities, mammographyis the last analogue (film) technology holdout, although there is a strong incentive to become completely digital andto eliminate the costs and inefficiencies associated with chemical processing and archiving of films.2.2. FACTORS TO CONSIDER IN CHOOSING A DIGITAL MAMMOGRAPHY SYSTEMIn some countries, the sale of digital mammography equipment is heavily regulated and the manufacturer hasto demonstrate that performance meets certain standards. In others, standards are far less demanding. Whether ornot rigorous standards exist in a given Member State, when considering the purchase of a digital system, it isvaluable to examine whether that system has been approved in countries that do enforce such standards. It maytherefore be useful to refer to the web sites of national or regional agencies such as the European ReferenceOrganisation for Quality Assured Breast Screening and Diagnostic Services (EUREF) (www.euref.org), the UnitedKingdom’s National Health Service Breast Screening Programme (www.cancerscreening.nhs.uk/breastscreen/), theUnited States Food and Drug Administration (FDA) (http://www.fda.gov/cdrh/mammography) or other nationalsites where lists of acceptable models or assessment reports of performance are available.The digital mammography system is a complex chain that includes the X ray unit and detector, software,display workstations, the picture archiving and communications system (PACS) and, possibly, printers. For thesystem to be effective and to provide improved performance over film mammography, all these components mustbe of high quality and must work effectively together. An example of the sort of problems that can occur whencomponents do not work together is given in Ref. [17].2It should be noted that depending on the system design, the choice of technique factors and attention to QC, doses in digitalmammography can be either lower or higher than those in screen film mammography.4
The Integrating the Healthcare Enterprise (IHE) mammography handbook is useful for those whoprepare request for proposal (RFP) documents for digital mammography (http://www.ihe.net/Resources/upload/IHE_Mammo_Handbook_rev1.pdf). To help the reader to understand the concepts and language of the IHEstandard, selected sections of the IHE manuals pertinent to digital mammography have been abstracted; a link to theextracted material is provided in Annex III. By specifying how systems interact, the standard attempts to ensure thatimages from different brands of mammography machines will be displayed in a consistent manner on all brands ofreview workstations.At the very minimum, an RFP should include the requirements shown in the box below:For the Image Acquisition WorkstationThe IHE mammography image integration profile is supported as an acquisition modality actor.The IHE scheduled workflow profile (SWF) integration profile is supported as an acquisition modality actor.The IHE portable data for imaging (PDI) integration profile is supported as a media creator actor.For the Image Display WorkstationThe IHE mammography image integration profile is supported as a display modality actor.The IHE mammography image integration profile is supported as a print composer actor.The IHE PDI integration profile is supported as a media creator actor.There is likely to be a supply of used systems available over the next few years. The donation and receipt ofused equipment is problematic and should be carefully considered [18]. Such equipment must be examined verycarefully to determine whether its performance can and does meet current standards. For example, the detectors onsome older models may not be large enough to accommodate the full range of breast sizes. The cost of bringing aused system into compliance must be carefully considered.A wide range of costs are associated with the different technologies available for digital mammography.Because of differences in design, there are substantial differences in imaging performance in terms of dose andimage quality. Purchasers of digital mammography systems are strongly advised that the use of equipment havingmarginal performance can compromise clinical outcome and result in higher overall cost due to reduced throughputand the potential for medicolegal issues.2.2.1. Analysis of requirementsIn the light of the current status of digital mammography and the factors to be considered in choosing a digitalmammography system, the following points of analysis should be considered:— Decide if the system is to be used for screening mammography, diagnostic mammography or both. If thesystem is to be used for diagnostic imaging, it should normally be equipped with a small focal spot andmagnification capability. This is not necessary for machines used exclusively for screening mammography.— Ensure that the system is capable of supporting the required imaging volume. Screening facilities frequentlyhave a much higher daily workload (e.g. up to 100 women per day) than do diagnostic units. This imposesrequirements on the heat loading capability of the X ray tube, the minimum time between exposures requiredby the image receptor and the throughput of a photostimulable phosphor (PSP) plate reader (if one is used).— Establish whether there will be a requirement to integrate stereotactic biopsy systems with the digital X raysystem, as could be the case for some diagnostic facilities.5
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 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 and 28: 2.3.8.1. Soft copy displayFlat pane
Page 29 and 30: 3. ELEMENTS OF HIGH QUALITY MAMMOGR
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
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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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8.10.2. 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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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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