School of Health Sciences, University of Salford, Salford, UK.
Br J Radiol. 2013 Jan;86(1021):20120222. doi: 10.1259/bjr.20120222.
To perform a calibration study to provide data to help improve consistency in the pressure that is applied during mammography.
Automatic readouts of breast thickness accuracy vary between mammography machines; therefore, one machine was selected for calibration. 250 randomly selected patients were invited to participate; 235 agreed, and 940 compression data sets were recorded (breast thickness, breast density and pressure). Pressure (measured in decanewtons) was increased from 5 daN through 1-daN intervals until the practitioner felt that the pressure was appropriate for imaging; at each pressure increment, breast thickness was recorded.
Graphs were generated and equations derived; second-order polynomial trend lines were applied using the method of least squares. No difference existed between breast densities, but a difference did exist between "small" (15×29 cm) and "medium/large" (18×24/24×30 cm) paddles. Accordingly, data were combined. Graphs show changes in thickness from 5-daN pressure for craniocaudal and mediolateral oblique views for the small and medium/large paddles combined. Graphs were colour coded into three segments indicating high, intermediate and low gradients [≤-2 (light grey); -1.99 to -1 (mid-grey); and ≥-0.99 (dark grey)]. We propose that 13 daN could be an appropriate termination pressure on this mammography machine.
Using patient compression data we have calibrated a mammography machine to determine its breast compression characteristics. This calibration data could be used to guide practice to minimise pressure variations between practitioners, thereby improving patient experience and reducing potential variation in image quality.
For the first time, pressure-thickness graphs are now available to help guide mammographers in the application of pressure.
进行校准研究，提供有助于提高乳房 X 光摄影过程中压力一致性的数据。
自动读取乳房厚度准确性读数在不同的乳房 X 光机之间存在差异；因此，选择了一台机器进行校准。随机邀请了 250 名患者参加，235 名同意，共记录了 940 个压缩数据集（乳房厚度、乳房密度和压力）。压力（以 decanewtons 为单位）从 5 daN 以 1-daN 的间隔增加，直到医生认为压力适合成像；在每个压力增量时，记录乳房厚度。
生成了图表并推导出了方程；使用最小二乘法应用二阶多项式趋势线。乳房密度之间没有差异，但“小”（15×29cm）和“中/大”（18×24/24×30cm）乳房托垫之间存在差异。因此，数据被合并。图表显示了从小乳房托垫的头尾位和内外斜位的 5-daN 压力下厚度的变化，以及中/大乳房托垫的厚度变化。图表按颜色编码为三个部分，指示高、中、低梯度[≤-2（浅灰色）；-1.99 至-1（中灰色）；和≥-0.99（深灰色）]。我们建议在这台乳房 X 光机上，13 daN 可以作为一个合适的终止压力。
使用患者的压缩数据，我们校准了一台乳房 X 光机，以确定其乳房压缩特性。该校准数据可用于指导实践，以尽量减少医生之间的压力变化，从而改善患者体验并降低图像质量的潜在变化。
这是首次提供压力-厚度图来帮助指导乳房 X 光摄影师施加压力。
