Digitised images are produced Monthly Produce an analogue film with Date test performed Film Digitiser QC (if that consistently and accurately a step pattern. This may Person performing test applicable) reproduce hard copy images. be generated automatically by The R2 value for the plot of MPV a laser printer, for example. A plot of MPV versus OD versus OD. should be linear over full Measure the Optical Densities range of OD from B+F to (OD) for each step Dmax with R2> 0.95 Digitise the image Measure the mean pixel value Note: If the plot of MPV (MPV) at a convenient place in versus OD is not linear, it each step could be due to the Plot the MPV versus OD using wrong LUT being selected an EXCEL spreadsheet. This by the equipment. This should be linear if the correct should be rectified by look up table (LUT) is used. service personnel. Note: The LUT is part of the software in the digitiser or workstation it is attached to. Obtain the value of the correlation coefficient (R2) using EXCEL for this plot. Overall repeat rate Quarterly Analysis of the proportion of Records showing: Repeat ≤2% analysis repeats attributable to positioning, Date analysis was performed. a range of equipment faults and Person performing analysis. other reasons for the quarter or from at least 250 consecutive Results of analysis and any corrective client examinations. actions taken.
Film Digitiser QC (if applicable) Digitised images are produced that consistently and accurately reproduce hard copy images. A plot of MPV versus OD should be linear over full range of OD from B+F to Dmax with R2> 0.95 Note: If the plot of MPV versus OD is not linear, it could be due to the wrong LUT being selected by the equipment. This should be rectified by service personnel. Monthly Produce an analogue film with a step pattern. This may be generated automatically by a laser printer, for example. Measure the Optical Densities (OD) for each step Digitise the image Measure the mean pixel value (MPV) at a convenient place in each step Plot the MPV versus OD using an EXCEL spreadsheet. This should be linear if the correct look up table (LUT) is used. Note: The LUT is part of the software in the digitiser or workstation it is attached to. Obtain the value of the correlation coefficient (R2) using EXCEL for this plot. Date test performed Person performing test The R2 value for the plot of MPV versus OD. Repeat analysis Overall repeat rate ≤2% Quarterly Analysis of the proportion of repeats attributable to positioning, a range of equipment faults and other reasons for the quarter or from at least 250 consecutive client examinations. Records showing: Date analysis was performed. Person performing analysis. Results of analysis and any corrective actions taken.
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