QC in a Digital World - BC Centre for Disease Control
Safety Code 35 John Aldrich PhD FCCPM Regional Leader Clinical Physics Kevin Hammerstrom RTNM QC Coordinator Department of Radiology Vancouver Coastal Health University of British Columbia Medical X-ray Safety Codes Safety Code 20A (1976) Safety Code 35 (2008) (two drafts in 2005 and 2007) Recommended safety procedures for the installation, use and control of x-ray equipment. Mainly concerned with the x-ray output parameters of the equipment Only film processor QC defined Comprehensive safety
procedures for the installation, use and control of x-ray equipment. Includes all x-ray systems Increased emphasis on patient dose 25% of the Code is concerned with QC of digital imaging systems Safety Code 35 A1. Responsibilities of owners and users (4) A2. Procedures for minimizing staff dose (2) A3. Procedures for minimizing patient dose (6) B1. Facility shielding (3) B 2-6. Equipment performance (15) C 1-3. Quality Control (17) Appendices (30) Decoding the Code Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS
Handout includes all slides in our presentations Attached sheets have all the tables enlarged References are to details of the tests in the Code eg D1 is the first daily test listed, W1 weekly, M1 - monthly, Q1 quarterly, SY1 semiannually, Y1 - Annual Overview Session 1 Requirements for all systems 20 Radiation Protection 10 Questions 10 Radiography (Film/DR/CR) 20 Radioscopy (Fluoroscopy, Angio, DF)
10 Personnel qualifications 20 Education and training 10 Questions 20 Daily Quality Control Tests Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS Quality Control Procedures Filmbased All Systems
Daily Quality Control Tests According to manufacturers instructions Can include auto calibration eg CT Equipment Warm-up (D1) Meters Operation (D2) Equipment Conditions (D3) Darkroom Cleanliness (D5) Film Processor Function (D6) Overall Visual Assessment of Electronic Display Devices (D7) Meter, visible and audible indicators should function Visual inspection for loose or broken components, ease of movements (M DAP) (M DAP) Display SMPTE or QC pattern for general image quality of all Radiologists workstations Check 5% and 95% areas visible Weekly and Monthly Tests Quality Control Procedures
All Systems Weekly Quality Control Tests Viewbox condition (W2) Laser Film Printer Operation (W3) Visual inspection for cleanliness, colour, illumination Print pattern such as SMPTE or PQC Check for 0/5% and 95/100% patch visibility OD of 10% to 90% patches No artifacts or geometrical distortion Monthly Quality Control Tests Darkroom Temperature and Humidity (M2) Temp: 18-23C; Humidity 40-60% Darkroom Light Conditions (M3) Visual check for light tightness Film Processor Operation (M4) Electronic Display Device Performance (M6)
Laser Film Printer Operation (M7) Temp 0.5C; Developer and fixer correct (M DAP) Display pattern such as SMPTE or QC on all image display devices As W3 plus measurement of optical density of the 10% to 90% grey scale Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS Quarterly and Annual Tests Quality Control Procedures All Systems Quarterly Quality Control Tests Interlocks (Q2) These are not usually used on diagnostic doors Annual Quality Control Tests
Safelight Test (Y1) Film/Screen Contact (Y2) Expose film for 2 min Image mesh and check Viewboxes (Y26) Check luminance, uniformity, homogeneity, ambient light Electronic Display Device Performance (Y27) All clinical workstations must be calibrated for luminance, distortion, resolution and noise Integrity of Protective Equipment (Y28) Lead aprons, glasses, integral shields General Preventive Maintenance (Y29) As per manufacturer Normal Font Required Test (must do)
Italics - Recommended Test (recommended) Required Tests currently recommended by RPS Display QC Daily (D7) for clinical interpretation Radiologist at each login Find suitable SMPTE test pattern Make accessible on PACS Test using various user logins/profiles Alert radiologists of requirement, frequency, and procedure Problems with inconsistency Left Display 5% visible / 95 % not visible
Right Display 5% not visible / 95 % visible Should see both 5% and 95% squares if calibrated properly Display QC Monthly (M6) All displays Technologist PACS administrator Biomed SMPTE test pattern / test pattern generator / vendor Display QC Annually (Y27) Clinical interpretation and
interventional use QC Coordinator PACS administrator Biomed SMPTE test pattern / test pattern generator / vendor QC software and photometer Viewbox QC Weekly visual inspection (W2) Cleanliness Viewing area discolouration
Should Light output uniformity +/- 10% Should Light output homogeneity +/- 20% Should Ambient light control < 50 lux (50 cd/m2) 5-10 lux recommended (5-10 cd/m2) Must Viewbox QC Laser Film Printer QC
Weekly (W3) Use same viewbox panel Print SMPTE from PACS workstation or from printer menu View 5% and 95% grayscale squares Maintain logsheet Laser Film Printer QC Laser Film Printer QC Monthly (M7) Use same viewbox panel
Print SMPTE from PACS workstation or from printer menu Measure optical density of grayscale gradient squares, geometrical distortions, artifacts View 5% and 95% squares and compare densitometer readings Maintain logsheet Laser Film Printer QC Overview Session 1
Requirements for all systems 20 Radiation Protection 10 Questions 10 Radiography DR/CR 20 Radioscopy (Fluoroscopy, Angio), DF 20 Questions 10
LUNCH Radiation Protection Radiation Safety Officer (1.4) Room Shielding (5.0) Lead aprons (4.1) Radiation Safety Officer There must be a Medical Physicist or Radiation Safety Officer to advise on all aspects of Radiation Safety Planning, registration, inspection Working conditions, procedures Classification of personnel, dosimetry Record keeping, investigations Radiation Protection - Shielding Design of Shielding
Recommend NCRP 147 (2004) methods which are based on empirical data (although Appendix is NCRP 49 (1976) which will tend to overshield rooms) Surveys of rooms must be done for new or altered rooms (equipment, use or vicinity Sec A5) Design shielding Check lead installation Measure radiation in surrounding areas Lead Aprons
Lead equivalence of aprons SC 20A <150 kVp 0.5 mm SC 35 < 100 kVp: 100< kVp <150: >150 kVp: 0.25 mm 0.35 mm 0.5 mm Lead apron QC Annually (Y28)
Radiographic / radioscopic Rejection if total defective area > 670 mm 2 Thyroid and reproductive areas < 5 mm diameter equivalent total Overview Session 1 Requirements for all systems 20 Radiation Protection 10 Questions 10 Radiography DR/CR 20
Radioscopy (Fluoroscopy, Angio), DF 20 Questions 10 LUNCH Overview Session 1 Requirements for all systems 20 Radiation Protection 10 Questions 10 Radiography DR/CR
20 Radioscopy (Fluoroscopy, Angio), DF 20 Questions 10 LUNCH Equipment Life Cycle Acceptance testing Acceptance testing New equipment Conformance to manufacturers
specifications/RFP Baseline performance Baseline value determination Device use period Routine performance evaluations Next constancy testing Data evaluation Specific tests performed at regular intervals Consistency checks Evaluate malfunctioning or outof-spec equipment Within the PASS
established criteria FAIL Remedy Imaging QC Principles Proactive QC rather than Reactive QC Test Patient tool/phantom the rated System performance rated Systemreplaces performance phantom Standard BEFOREimaging clinical imaging AFTER clinical imaging. Non-standard imaging parameters/conditions Scheduled testing (Daily/Weekly)
parameters/conditions Frequent testing (every patient) Defined and objective Which approach would you Ill-defined and subjective acceptance/rejection criteria prefer if you were a patient?? acceptance/rejection criteria Radiographic Systems Projection radiography Film Digital detectors (DR) Computed radiography (CR)
Weekly Radiographic Tests Quality Control Procedures Film CR DR Comments Visual Inspection of Imaging Systems W1 W1 W1 Inspect screens/CR plates/DR housing Viewboxes Condition W2
W2 W2 Cleanliness, luminance W3 W3 Print pattern such as SMPTE Weekly Quality Control Tests Laser Film Printer Operation Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS Monthly Radiographic Tests Quality Control Procedures Film
CR DR Comments Cassette, Screen, and Imaging Plate Cleaning M1 M1 Darkroom Temperature and Humidity Conditions (DAP) M2 Temp: 18-23C; Humidity 40-60% Darkroom Light Conditions M3
Visual check for light tightness Film Processor Operation M4 Temp 0.5C; Developer and fixer correct Retake Analysis M5 Monthly Quality Control Tests Electronic Display Device Performance Laser Film Printer Operation Clean screens/CR plates/DR housing M5
M5 For film, CR and DR M6 M6 Display pattern such as SMPTE on all image display stations M7 Print pattern such as SMPTE Check for 0/5% and 95/100% patch visibility OD of 10% to 90% patches No artifacts or geometrical distortion M7 Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS
Annual Radiographic Tests (1) Quality Control Procedures Film CR DR Comments Annual QC Tests Safelight Test Y1 Expose film for 2 mins in room Film/Screen Contact Y2 Image mesh and check
Accuracy of Loading Factors Y3 Y3 Y3 mAs Linearity Radiation Output Reproducibility Y4 Y4 Y4 Reproducibility Radiation Output Linearity Y5
Y5 Y5 Output with mAs X-ray Beam Filtration Y6 Y6 Y6 HVL Automatic Exposure Control Y7 Y7 Y7
Check AEC for all kVps and thicknesses X-ray Field and Light Field Alignment Y8 Y8 Y8 Congruency of x-ray beam and light field edges X-ray Beam Collimation Y9 Y9 Y9 Congruency of x-ray beam and light field
centres Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS Annual Radiographic Tests (2) Quality Control Procedures Film CR DR Comments Y10 Y10 Y10 Check uniformity and movement of grid
Exposure Index Y12 Y12 Exposure Index versus Dose 1 to 50 Gy Noise, Uniformity and Image Artifacts Y14 Y14 For above range of dose measure noise in center and each quadrant Check for artifacts Image Quality Grid Performance Spatial Resolution
Y15 Y15 Y15 Line-pair or Leeds phantom Contrast Detectability Y16 Y16 Y16 Leeds phantom Y17 Y17 Take image at 50 Gy then zero;
check for artifacts Y18 Y18 Measure dose at surface of standard phantom eg 20 cm PMMA Digital Detector Residual Images Phantom Dose Measurements Y18 DAP Meter Calibrate Normal Font Required Test (must do) Italics - Recommended Test (recommended) Required Tests currently recommended by RPS Digital Imaging
Any sufficiently advanced technology is indistinguishable from magic Arthur C Clarke 1961 Digital X-ray Systems Direct Radiography DR Formation of image without a secondary read-out device Computed Radiography CR Use of storage phosphor plate usually in a cassette-based system Digital System QC Film Developed And Fixed
Detector Reading Digital Processing Stored PACS Viewed Display QC of the digital systems is an additional requirement in addition to the usual x-ray performance tests - it is not performed magically DR, CR and DF Extra QC
Dose Calibration Spatial Resolution Low Contrast Uniformity Artifacts Dose Calibration Each system should be calibrated according to the manufacturers protocol, as they are all slightly different General set-up Arrange for defined dose at surface of cassette at 80 kVp Expose and read image
Record Exposure Index The image can also be used to check for uniformity, linearity and artifacts Image Quality All CR and some DR/DF manufacturers have custom Image Quality phantoms and automatic software to analyze image quality Resolution and Contrast Any high contrast resolution phantom can be used to provide comparative information Low contrast resolution is one of the most difficult parameters to measure. There are several phantoms and measurement is subjective, so consistent technique is essential Image Noise is usually be a good indicator of consistency Digital Radiography QC Many DR systems require more frequent
calibration of the uniformity eg every month Flat field measurement (uniform Cu orAl plate) Uniformity correction Noise Artifacts Contrast-detail and resolution phantom CR & DR QC Weekly visual inspection (W1) Dust / dirt Clean if necessary
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