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7.2.4. Image quality with breast mimicking phantom7.2.4.1. ScopeThis test is provided as an interim measure, to be used as an alternative to the tests described in Section 7.2.3in cases where quantitative analysis tools for QC are not made available to the user. Such tools are considered to beimportant as part of overall QA, and their absence is considered to be an unacceptable situation for the long term.Generally, a quantitative test is preferable, as it is more objective and reproducible. No particular phantom can berecommended. Instead, a facility could use whatever nationally or internationally recommended phantom iscurrently used for its screen film programme.— Objective: To ensure that the overall image quality has not degraded from baseline performance levels andthat there are no obvious artefacts.— Minimum frequency: Weekly.7.2.4.2. Instrumentation(1) Breast phantom containing structures mimicking those found in the breast.(2) Baseline phantom image (This should have been retained from a previous physics testing, at acceptance orcommissioning).(3) Magnifying lens (4× to 5× magnification, only for images on hard copy).7.2.4.3. Methodology(1) Place the phantom on the breast support, positioned flush with the chest wall and centred laterally.(2) Lower the compression paddle to apply a clinically realistic compression force (e.g. 80 N).(3) If there is a separate AEC sensor, confirm that it is under the phantom.(4) Make an exposure with the technique factors used in the clinical practice for a breast with characteristicsequivalent to those of the phantom. Normally this is achieved by using the automatic exposure mode.Otherwise, select the appropriate target, filter, kV, grid, density control position and operation mode(semiautomatic or automatic).(5) On the corresponding data collection sheet, record the exposure factors and technique used; for CR systems,record the EI (see Table 6).(6) Process the image using the algorithms that would be used clinically.(7) View this image in a manner similar to that used clinically. Ideally, this should be done on the radiologistworkstation. If this is not possible, it can be done on the acquisition workstation. Images should be evaluatedon the viewbox if interpretation is done from printed films.(8) Compare this image with the baseline image obtained on this system. Determine if there are artefacts that maybe confused with any of the phantom details. With suitable magnification, carefully examine the image fornon-uniform areas, the effects of dirt or dust, lines, image processing artefacts or any other type of artefact.(9) If desired, evaluate the image according to the evaluation method provided by the manufacturer 5 . Record thedata on a data collection sheet (e.g. Chart 8 in Annex I), and record the test outcome on the daily and weeklychecklist (Chart 1 in Annex I).(10) Investigate the causes of any artefacts.5A description of how this is done for the American College of Radiology (ACR) accreditation phantom is provided in thereport Quality Assurance Programme for Screen Film Mammography (IAEA Human Health Series No. 2 [34]).62
7.2.4.4. Interpretation of results and conclusionsTolerances:(1) The mAs used for the phantom exposure should be within ±10% of the baseline mAs value if the kV and filterhave not changed.(2) For CR systems, the tolerances for the EI given in Table 7 should not be exceeded.(3) There should be no significant degradation of image quality from the baseline image. Note that the imagequality assessment of the phantom should yield results that are as good as or better than those expected withhigh quality screen film mammography as tested with the same phantom.(4) There should be no blotches or regions of altered noise appearance.(5) There should be no observable lines or structural artefacts.(6) There should be no ‘bright’ or ‘dark’ pixels evident.7.2.4.5. Recommendations and corrective actionsIf results are outside the tolerances or are unacceptable, the tests should be repeated. If the results remainunacceptable, it may be appropriate to contact the responsible medical physicist for further advice on implementingthe recommendations listed below:(1) If the image quality deteriorates over time, it will be necessary to carry out other investigations to determinethe source of the change 6 . A simple review of whether appropriate settings (e.g. kV, AEC, display, processingalgorithms) have been used may reveal the source of the problem. Verify whether there has been a softwareupgrade of the system that has changed the AEC settings. Otherwise, a more serious underlying problem mayrequire the assistance of the medical physicist.(2) If any artefacts are visible that might mimic or obscure anatomic information, or if any patterns are seen, arecalibration or flat fielding of the digital detector is needed. After this has been done, repeat the artefactphantom test. If artefacts persist, contact the authorized service representative.7.2.4.6. Time frame for corrective actionImmediately: If this test fails, do not image patients until corrective action has been taken.6Due to the subjectivity associated with the observer, it is recommended that the test always be performed by the same person,using the same criteria and viewing conditions.63
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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
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
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: TABLE 7. TOLERANCES FOR IMAGING WEE
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 and 122: 8.7. X RAY EQUIPMENT CHARACTERISTIC
Page 123 and 124: 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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