A comparison of calibration data from full field digital mammography units for breast density measurements.
A comparison of calibration data from full field digital mammography units for breast density measurements.
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DOI：
10.1186/1475-925x-12-114
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发表时间：
2013-11-09
影响因子：
3.9
通讯作者：
Heine JJ
中科院分区：
文献类型：
--
作者：
Fowler EE;Lu B;Heine JJ
乳房密度是乳房x光检查中一个重要的乳腺癌风险因素。测量乳腺密度的最合适方法仍在研究中。校准使乳房x线照片标准化，以便在进行乳腺密度测量之前考虑采集技术的差异。我们评估了为间接x射线转换全场数字乳房x线摄影（FFDM）技术开发的校准方法是否适用于直接x射线转换FFDM系统。使用乳腺组织等效（BTE）幻象图像建立三个类似的直接x射线转换FFDM系统的校准数据集。每个单元的校准数据集是目标/滤波器组合、x射线管电压、电流×时间（mAs）、幻像高度和两个探测器视场（fov）的函数。研究了通过限制高度、mAs和视场采样来减少标定数据量的方法。用混合幻影评价校准精度。我们还比较了系统内和系统间的校准特性和精度。以前开发的校准方法适用于修改后的直接x射线转换系统。在直接转换单元的整个采集参数空间上，校准精度基本上在±4个标准单位的理想值的可接受范围内。通过三次样条高度插值保持了可接受的校准精度，这是对先前工作的修改。校准数据是单位特定的，可以用大视场获得，并且需要至少一个参考mAs样本。mAs采样、校准精度和机器特定校准数据的必要性是共同的特点，与我们以前的工作一致。在理想条件下，建立了标定方法的通用性。需要以乳腺癌状态为终点的患者数据进行评估，以证明该方法产生与乳腺癌相关的乳腺密度测量。
Breast density is a significant breast cancer risk factor measured from mammograms. The most appropriate method for measuring breast density for risk applications is still under investigation. Calibration standardizes mammograms to account for acquisition technique differences prior to making breast density measurements. We evaluated whether a calibration methodology developed for an indirect x-ray conversion full field digital mammography (FFDM) technology applies to direct x-ray conversion FFDM systems. Breast tissue equivalent (BTE) phantom images were used to establish calibration datasets for three similar direct x-ray conversion FFDM systems. The calibration dataset for each unit is a function of the target/filter combination, x-ray tube voltage, current × time (mAs), phantom height, and two detector fields of view (FOVs). Methods were investigated to reduce the amount of calibration data by restricting the height, mAs, and FOV sampling. Calibration accuracy was evaluated with mixture phantoms. We also compared both intra- and inter-system calibration characteristics and accuracy. Calibration methods developed previously apply to direct x-ray conversion systems with modification. Calibration accuracy was largely within the acceptable range of ± 4 standardized units from the ideal value over the entire acquisition parameter space for the direct conversion units. Acceptable calibration accuracy was maintained with a cubic-spline height interpolation, representing a modification to previous work. Calibration data is unit specific, can be acquired with the large FOV, and requires a minimum of one reference mAs sample. The mAs sampling, calibration accuracy, and the necessity for machine specific calibration data are common characteristics and in agreement with our previous work. The generality of our calibration approach was established under ideal conditions. Evaluation with patient data using breast cancer status as the endpoint is required to demonstrate that the approach produces a breast density measure associated with breast cancer.