K J ROBSON
Br J Radiol 2008;81 219-231
http://bjr.birjournals.org/cgi/content/abstract/81/963/219?etoc
The ability of an observer to detect objects on a radiograph is influenced by the conditions under which the image is viewed. Therefore, to ensure that as much diagnostically relevant information as possible can be extracted from the image, it is important that satisfactory viewing conditions for the task are established and maintained. Factors that are thought to be important are the luminance of the image, glare and ambient light. Together, these factors lead to the formation of reflection on the image, which may degrade the observer's performance. The purpose of this study was to explore, in a systematic manner, the effect of the factors outlined above on the performance of an observer conducting a threshold contrast–detail diameter test. Each factor was investigated separately with attempts made to minimize the confounding effects of other factors. When examined individually, viewing box luminance, ambient light and glare were found to have little effect on the contrast–detail performance of the observers. Reflection was found to have a significant effect, particularly non-uniform reflection, and the magnitude of the effect was related to the contrast degradation factor and reflection modulation. These quantities, which are derived from basic photometric measurements, may be used to develop a protocol to assess viewing conditions in screen-film mammography.
Wednesday, 13 February 2008
Trends in compressed breast thickness and radiation dose in breast screening mammography
M ROBINSON and C J KOTRE
Br J Radiol 2008;81 214-218
http://bjr.birjournals.org/cgi/content/abstract/81/963/214?etoc
An analysis was performed of the compressed breast thickness recorded in 146 mammographic patient dose surveys each consisting of 50 or more women carried out between 1993 and 2004. The results show a steady and statistically significant increase in compressed breast thickness with time, which is also present when individual independent screening centres and equipment manufacturers are compared. This increase seems most likely to be associated with an increase in the proportion of women in the breast screening age range classified as overweight and obese, which has occurred over the same time period. The associated trends in mean glandular dose per image were calculated for the mammography units used at the time of the surveys, using the most recently published conversion factors. The increase in average radiation dose that might have been expected as a result of the increase in average compressed breast thickness was not actually found in practice, possibly because of advances in equipment design and dose optimization strategies made during the 11-year period. Other implications of an increasing average compressed breast thickness are discussed.
Br J Radiol 2008;81 214-218
http://bjr.birjournals.org/cgi/content/abstract/81/963/214?etoc
An analysis was performed of the compressed breast thickness recorded in 146 mammographic patient dose surveys each consisting of 50 or more women carried out between 1993 and 2004. The results show a steady and statistically significant increase in compressed breast thickness with time, which is also present when individual independent screening centres and equipment manufacturers are compared. This increase seems most likely to be associated with an increase in the proportion of women in the breast screening age range classified as overweight and obese, which has occurred over the same time period. The associated trends in mean glandular dose per image were calculated for the mammography units used at the time of the surveys, using the most recently published conversion factors. The increase in average radiation dose that might have been expected as a result of the increase in average compressed breast thickness was not actually found in practice, possibly because of advances in equipment design and dose optimization strategies made during the 11-year period. Other implications of an increasing average compressed breast thickness are discussed.
Cancer surveillance based on imaging techniques in carriers of BRCA1/2 gene
Cancer surveillance based on imaging techniques in carriers of BRCA1/2 gene mutations: a systematic review
M J BERMEJO-PEREZ, S MARQUEZ-CALDERON, and A LLANOS-MENDEZ
Br J Radiol 2008;81 172-179
http://bjr.birjournals.org/cgi/content/abstract/81/963/172?etoc
We have systematically reviewed the literature focusing on the performance of surveillance programmes and imaging techniques for the early diagnosis of breast and ovarian cancer in women carrying mutations in BRCA1/2 genes. All studies on imaging techniques for the diagnosis of breast cancer indicated that screening MRI had the highest sensitivity (between 77% and 100%). Breast cancer surveillance programmes, including MRI, achieved the highest diagnostic performance (between 83% and 95%) for all women. However, it must be taken into account that biases that may affect the validity of the outcomes were seen in the evaluated studies. Also, MRI is an expensive test with a low positive predictive value and, to date, MRI screening has not been proven to reduce mortality rates in women carrying BRCA1/2 gene mutations. As a result of the scant information and low quality of the papers reviewed, no definitive conclusion could be drawn on the performance of ovarian cancer surveillance in women carrying BRCA1/2 mutations.
M J BERMEJO-PEREZ, S MARQUEZ-CALDERON, and A LLANOS-MENDEZ
Br J Radiol 2008;81 172-179
http://bjr.birjournals.org/cgi/content/abstract/81/963/172?etoc
We have systematically reviewed the literature focusing on the performance of surveillance programmes and imaging techniques for the early diagnosis of breast and ovarian cancer in women carrying mutations in BRCA1/2 genes. All studies on imaging techniques for the diagnosis of breast cancer indicated that screening MRI had the highest sensitivity (between 77% and 100%). Breast cancer surveillance programmes, including MRI, achieved the highest diagnostic performance (between 83% and 95%) for all women. However, it must be taken into account that biases that may affect the validity of the outcomes were seen in the evaluated studies. Also, MRI is an expensive test with a low positive predictive value and, to date, MRI screening has not been proven to reduce mortality rates in women carrying BRCA1/2 gene mutations. As a result of the scant information and low quality of the papers reviewed, no definitive conclusion could be drawn on the performance of ovarian cancer surveillance in women carrying BRCA1/2 mutations.
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