Light sensitometry of mammography films at varying development temperatures and times.
ABSTRACT Kodak MinR-2000 mammography film is widely used for mammography imaging. The sensitometric indices like base plus fog level (B + F), maximum optical density (OD(max)), average gradient (AG) and speed of this film at varying development temperatures and times were evaluated using a light sensitometer. Totally 33 film strips were cut from a single Kodak MinR-2000 mammography film box and exposed in a light sensitometer operated in the green light spectrum to produce a 21-step sensitometric strip. These exposed film strips were processed at temperatures in the range of 32°C-37°C in the step of 1°C and at processing times in the range of 1-6 minutes in the step of 1 minute. The results of the present study show that the measured base plus fog level of the mammography film was not affected much, whereas significant changes were seen in the OD(max), AG and speed with varying development temperatures and times. The OD(max) values of the film were found in the range of 3.67-3.76, AG values were in the range of 2.48-3.4 and speed values were in the range of 0.015-0.0236 when the processing temperature was varied from 32°C to 37°C. With processing time variation from 1 to 6 minutes, the observed changes in OD(max) values were in the range of 3.54-3.71, changes in AG were in the range of 2.66-3.27 and changes in speed were in the range of 0.011-0.025. Based on these observations, recommendations for optimum processing parameters to be used for this film are made.
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ABSTRACT: In contrast to the majority of mammographic breast screening programmes, film processing at this centre occurs on site in both hospital and mobile trailer units. Initial (1989) quality control (QC) sensitometric tests revealed a large variation in film processor performance in the mobile unit. The clinical significance of these variations was assessed and acceptance limits for processor performance determined. Abnormal mammograms were used as reference material and copied using high definition 35 mm film over a range of exposure settings. The copies were than matched with QC film density variation from the mobile unit. All films were subsequently ranked for spatial and contrast resolution. Optimal values for processing time of 2 min (equivalent to film transit time 3 min and developer time 46 s) and temperature of 36 degrees C were obtained. The widespread anomaly of reporting film transit time as processing time is highlighted. Use of mammogram copies as a means of measuring the influence of film processor variation is advocated. Careful monitoring of the mobile unit film processor performance has produced stable quality comparable with the hospital based unit. The advantages of on site film processing are outlined. The addition of a sensitometric step wedge to all mammography film stock as a means of assessing image quality is recommended.British Journal of Radiology 01/1993; 65(780):1097-101. · 1.53 Impact Factor
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ABSTRACT: High image quality and low radiation levels are essential in mammography. This study investigates the effect of changes in processor temperatures and developing times on sensitometric findings. These findings were matched with the changes in the image quality during similar changes in the developing parameters. Temperatures ranging between 35 degrees C and 40 degrees C and developing times from 20 s and 50 s were investigated. Higher developing temperatures and increased developing times resulted in an increase in film speed and film contrast. A definite pattern of change could be demonstrated in film speed and film contrast during sensitometry. The same pattern of change could, however, not be demonstrated in the quality of phantom images under similar circumstances. The base plus fog level was not adversely affected. Sensitometric findings of film speed can be effectively used as an indicator of radiation exposure to the patient, but cannot be used to establish the developing parameters that will give the best image quality. Both these methods should be used to determine which processing variables should be used to obtain a combination of the best image with radiation as low as possible. Recommendations for optimum processing parameters are made for the films and processing chemistry investigated.British Journal of Radiology 09/1993; 66(788):685-90. · 1.53 Impact Factor
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ABSTRACT: The performance of commercially available light sensitometers was compared with two other methods of x-ray sensitometry to determine whether commercially available sensitometers are viable for evaluating clinical performance of mammography film. X-ray sensitometry was performed using mammography screens that were modified to accommodate a graded optical step tablet (screen sensitometry). Finally, a means for performing intensity-scale x-ray sensitometry was configured (inverse-square sensitometry). Clinical mammography x-ray exposure conditions were used and film processing quality was closely monitored during the study. Statistical results for chi-square probabilities on the resulting contrast curves yielded good agreement for most of the configurations investigated. Comparison of film gradient versus optical density curves showed good agreement for maximum contrast values and the corresponding optical density for maximum contrast for three of the four screen-film combinations used when comparing light sensitometry to screen sensitometry. A similar comparison of light sensitometers to inverse-square sensitometry showed good agreement for maximum contrast, but less agreement for the corresponding optical density of maximum contrast. Based on these results, the authors concluded that commercially available sensitometers could be used to estimate clinical film performance for the screen-film systems tested. In particular they can be used to determine the range of optical densities that provide optimal film contrast.Medical Physics 06/2000; 27(5):854-60. · 3.01 Impact Factor