Medical Physics College Trieste Mammography Quality Control (QC) Franco Milano Dept.Clinical Physiopathology University of Florence

Medical Physics College Trieste Quality System Quality Assurance (QA) Quality Audit Quality Control (QC) Definition of terms

Medical Physics College Trieste Quality System (IEC 1988) An effective Quality System will help to achieve and mantain: Radiological information of adequate quality for medical diagnosis purpose Minimum radiation dose to the patient and medical staff, compatible with adequate quality of the radiological information Maximum cost containment by minimising wastage of time and resources (e.g. reduction of rejected films) Good profession practice

Medical Physics College Trieste Definitions - 1 (WHO 1988) Quality Assurance : a more general term for the planned systematic actions necessary to ensure that a product or process performs satisfactory in service Quality audit : an independent review of the quality control system

Medical Physics College Trieste Definitions - 2 (WHO 1988) Quality control that process through which the actual quality performance of a product or process is measured, compared with existing standards and finally the action necessary to keep or regain conformance with the standard

Medical Physics College Trieste Quality in Mammography It depends critically on: the imaging x-ray equipment used and the way in which it is employed the screen-film system (cassette, film processing….) the radiographic technique (positioning, compression….) the “image” display ( illuminators and viewing room condition)

Medical Physics College Trieste Overall QC process: equipment PURCHASE AND INSTALLATION  Equipment specification  Acceptance test  Commissioning  Training DIAGNOSTIC SERVICE  Periodic checks (daily, weekly, monthly, yearly)  Documentation  Emergency repair  Preventive maintenance  Training

Medical Physics College Trieste Equipment specification BASIS FOR THE SELECTION OF THE EQUIPMENT Safety standard: related to the security of the patient and the personell Performance standard: related to the accuracy and quality of the diagnostic procedure

Medical Physics College Trieste Acceptance test Verify that the equipment meets the agree upon specifications  safety  performance Generally - the manufacturers responsability to demonstrate the performance and compliance, but - the customers responsability to verify the performance and compliance with specifications

Medical Physics College Trieste Commissioning Provide a complete data set for later comparison in a quality control program Radiation protection survey

Medical Physics College Trieste Performance standard TOLERANCE LEVEL when the parameter is in the range below the tolerance level the equipment is suitable for high quality imaging ACTION LEVEL when the action level is reached for a parameter the appropriate actions to restore it to below the tolerance level should be taken

Medical Physics College Trieste Quality Control (QC) Measurements X-ray generators Grid and image receptor Film processing System properties ( including dose) Viewing conditions

Medical Physics College Trieste Comparison between European Guideline edition European Guidelines for Quality Assurance in Mammography Screening Second Edition - European Guidelines for Quality Assurance in Mammography Screening Third Edition - January 2001 European Protocol for the Quality Control of the Physical and Technical Aspects of Mammography Screening

Medical Physics College Trieste Performance indicator European Guidelines for Quality Assurance in Mammography Screening Third Edition - January 2001 IndicatorAcceptable level Desiderable level Target optical density OD Spatial resolution>10 lp/mm>13 lp/mm Reference dose (surface entrance dose) <15 mGy<14 mGy Threshold contrast visibility <1.5%-

Medical Physics College Trieste Standard exposure - 1 Reference exposureRoutine exposure Test object thickness45 mm Test object materialPMMA Tube voltage28 kVas used clinically Target materialMoas used clinically Filter materialMoas used clinically

Medical Physics College Trieste Standard exposure - 2 Reference exposureRoutine exposure Compression deviceIn contact with test object Anti scatter gridPresent Source-to-image distance Matching with focused grid Phototimer detectorIn position closest to chest wall

Medical Physics College Trieste Standard exposure - 3 Reference exposureRoutine exposure Automatic exposure control onAs used clinically Optical density control As leading to the reference density As leading to the target optical density The OD of the processed image is measured at the reference point whichi lies 60 mm from the chest wall side and laterally centred The reference optical density is preferably 1.4 OD, base and fog excluded

Medical Physics College Trieste Parameters –Frequency – Limiting value – 1 X-ray sourceFrequencyTypical valueAcceptableDesiderable Focal spot sizeI0.3 mm Source-image distance I  600 mm Alignment x- ray/image receptor 12< 5 mm Film/bucky edge 12< 4 mm Radiation leakage I< 1 mGy/h Output6 > 30  Gy/mAs> 40  Gy/mAs Output rate6> 7.5mGy/s> 10 mGy/s

Medical Physics College Trieste Parameters –Frequency – Limiting value – 2 Tube voltage FrequencyTypical valueAcceptableDesiderable reproducibility6   0.5 kV Accuracy (25-31 kV) 6   1 kV HVL (Mo/Mo) – 0.4 mm Al> 0.3 mm Al

Medical Physics College Trieste Parameters –Frequency –Limiting value – 3 AECFrequencyTypical value AcceptableDesiderable Central opt. Dens control setting 6  0.15 OD Opt. Dens. Control step OD Adjustable range6> 1.0 OD> 1.0 DO Short term reproducibility 6  5 % OD  2 % OD Long term reproducibility D  0.2 OD  0.15 OD Obj.thick. comp.W  0.15 OD  0.10 OD Tube voltage comp. 6  0.15 OD  0.10 OD

Medical Physics College Trieste Parameters –Frequency –Limiting value – 4 CompressionFrequencyTypical value AcceptableDesiderable Compression force N Maintain force for121 min Compr. Plane align. Asym to nipple 12< 15 mm Compr. Plane align. Lat. Symm. to nipple 12< 5 mm

Medical Physics College Trieste Parameters –Frequency –Limiting value – 5 Anti scatter gridFrequencyTypical value AcceptableDesiderable Grid system factorI< 3 Film-screen Inter cassette sensitivity (mAs) 12  0.5 % mGy Inter cassette sensitivity (OD) 12  0.1 % OD  0.08 % OD Film-screen contact12

Medical Physics College Trieste Parameters –Frequency – Limiting value – 6 ProcessorFrequencyTypical valueAcceptableDesiderable TemperatureI °C Processing timeI90 s Film Base + fogD OD SpeedD Contrast gradMD Grad (a 1.0 OD net) D Daily performanceD< 10 %< 5 % ArtefactsD

Medical Physics College Trieste Parameters –Frequency – Limiting value – 7 DarkroomFrequencyTypical valueAcceptableDesiderable Light leakage ( OD extra fog 2 min *) 12<+0.02 OD Safelights (OD extra fog 2 min *) 12< OD Film hopperI< OD CassettesI * At net optical density 1.00 OD

Medical Physics College Trieste Parameters –Frequency – Limiting value – 8 Viewing boxFrequencyTypical value AcceptableDesiderable Brightness cd/m 2 Homogeneity12 <  30 % cd/m 2 Difference throughout dept. 12 <  15 % cd/m 2 Environment Ambient light level12< 50 lux

Medical Physics College Trieste Parameters –Frequency – Limiting value – 9 Reference dose image quality FrequencyTypical value AcceptableDesiderable Entrance dose (45 mm test object) 12< 15 mGy< 14 mGy Spatial resolutionW> 10 lp/mm > 13 lp/mm Image contrast variation W <  10 %<  5 % Threshold contrast visibility W1.5 % Exposure time12< 2 s< 1.5 s

Medical Physics College Trieste ° ed vs 3° ed

Medical Physics College Trieste ° ed vs 3° ed

Medical Physics College Trieste ° ed vs 3° ed

Medical Physics College Trieste ° ed vs 3° ed

Medical Physics College Trieste ° ed vs 3° ed

Medical Physics College Trieste ° ed vs 3° ed

Medical Physics College Trieste Breast model

Medical Physics College Trieste CIRS phantom

Medical Physics College Trieste GE phantom

Medical Physics College Trieste Leeds TOR (MAX) phantom

Medical Physics College Trieste Leeds TOR (MAX) phantom

Medical Physics College Trieste RMI mod.152 D phantom

Medical Physics College Trieste Bart phantom

Medical Physics College Trieste Dupont phantom

Medical Physics College Trieste