Young K C, Wallis M G, Blanks R G, Moss S M
Department of Medical Physics, St Luke's Wing, Royal Surrey County Hospital, Guildford, UK.
Br J Radiol. 1997 May;70(833):482-8. doi: 10.1259/bjr.70.833.9227229.
The National Health Service Breast Screening Programme (NHSBSP) has recommended the adoption of two view mammography at the prevalent screen, and the use of a target film density in the range 1.4-1.8. The aim of this study was to review the impact of number of views and optical density on the detection of invasive cancers. The last four annual returns for screening centres in the NHSBSP have been analysed retrospectively for 2827342 women aged 50-64 years attending their first (prevalent) screening examination. The detection of invasive cancers was assessed in relation to the number of views and film density using the age adjusted, Standardized Detection Ratio measure of screening performance. Typical film densities were reported for each screening year by local physicists, and the average value for all mammography sets at each programme calculated, and found to vary from 0.85 to 1.85. The mean film density across the NHSBSP rose progressively from 1.30 (SD = 0.21) in 1991/2 to 1.57 (SD = 0.12) in 1994/5. Programmes using single view mammography (MLO) and an optical density less than 1.4 detected 76% (95% CI 74-79%) of the expected invasive cancers. Programmes using two view mammography (MLO and CC) and an optical density equal to or greater than 1.4 detected 95% (95% CI 92-98%) of the expected invasive cancers. In 1994/95 when more programmes used the recommended screening modes, the NHSBSP detected 96% (95% CI 92-101%) of the expected invasive cancers at prevalent screening. The detection of invasive cancers was highest where programmes used two views with a film density in the range 1.4-1.8. The results provide evidence of the benefit of the recommended protocol for prevalent screening and indicate that from 1995/96 when all programmes will be using the recommended protocol, it is likely that the detection rates and interval cancer rates from prevalent screens in the NHSBSP will be close to the figures in the Swedish-Two County Trial.
国家医疗服务体系乳腺筛查计划（NHSBSP）建议在普查筛查时采用双视角乳腺X线摄影，并使用1.4 - 1.8范围内的目标胶片密度。本研究的目的是评估视角数量和光学密度对浸润性癌检测的影响。对NHSBSP中筛查中心过去四年的年度报告进行了回顾性分析，涉及2827342名年龄在50 - 64岁之间参加首次（普查）筛查的女性。使用年龄调整后的标准化检测率这一筛查性能指标，评估浸润性癌的检测情况与视角数量和胶片密度的关系。当地物理学家报告了每个筛查年度的典型胶片密度，并计算了每个项目所有乳腺X线摄影设备的平均值，发现其范围在0.85至1.85之间。NHSBSP的平均胶片密度从1991/92年的1.30（标准差 = 0.21）逐步上升至1994/95年的1.57（标准差 = 0.12）。采用单视角乳腺X线摄影（MLO）且光学密度小于1.4的项目检测到预期浸润性癌的76%（95%置信区间74 - 79%）。采用双视角乳腺X线摄影（MLO和CC）且光学密度等于或大于1.4的项目检测到预期浸润性癌的95%（95%置信区间92 - 98%）。在1994/95年，当更多项目采用推荐的筛查模式时，NHSBSP在普查筛查中检测到预期浸润性癌的96%（95%置信区间92 - 101%）。在采用双视角且胶片密度在1.4 - 1.8范围内的项目中，浸润性癌的检测率最高。研究结果为普查筛查推荐方案的益处提供了证据，并表明从1995/96年起，当所有项目都采用推荐方案时，NHSBSP普查筛查的检出率和间期癌发生率可能接近瑞典两县试验中的数据。
