Image Science for the New X-ray: Taking NEQ to Task

描述（由申请人提供）：平板成像仪（FPI）正在一系列先进的X射线成像模式中进行研究，这些模式可改善组织可视化和深度辨别，包括双能量（DE）成像、断层合成和锥形束CT（CBCT）。每一种都代表了诊断和图像引导程序的有前途的技术。在DE成像中，处理在不同X射线能量下采集的两个图像以产生骨骼或软组织的图像。在断层合成和CBCT中，X射线源和FPI在患者周围移动，并且从多个视角重建3D图像。实现这些模式的全部潜力需要定量评价成像性能和揭示限制图像质量的物理因素的方法。传统的基于傅立叶的度量，如噪声等效量子（NEQ），提供了实用的，普遍的空间分辨率和信噪比的品质因数。然而，对于这些先进的成像模态，目前没有严格的性能计量（基于傅立叶或其他）;此外，NEQ传统上仅描述检测器的性能，并且既不考虑图像中的感兴趣结构（即，#21453;，也没有观察员的反应。该提案采用基本的图像科学方法来评估这些先进模式的性能，在许多方面开辟了新天地：1。NEQ和相关的傅立叶度量扩展到每个高级模态，以提供用于成像性能评估的实验和理论方法; 2）图像中感兴趣的结构根据成像任务进行量化，考虑到与两种最致命的癌症（肺癌和肝转移）有关的各种简单和高阶任务（检测、定位和尺寸估计）;以及3.）成像任务和NEQ的定量配方严格结合，以产生基于任务的指标，在DE成像，断层合成，和CBCT成像性能，并在何种程度上，这种基于任务的指标提供了一个有意义的替代图像质量的验证与人类观察员的响应相关。因此，该提议开始弥合流行的基于傅立叶的方法和传统的基于傅立叶的方法（例如，ROC分析）。例如，使用DE成像和断层合成的检测和尺寸估计任务来评估肺结节早期检测中的成像性能，而根据CBCT的定位任务来评估肝转移的RF消融或放射治疗的引导。该计划的成功完成将提供一个实用的，任务驱动的方法来设计，评估和优化这些和其他新的成像模式。

DESCRIPTION (provided by applicant): Flat-panel imagers (FPIs) are being investigated in a host of advanced x-ray imaging modalities that offer improved tissue visualization and depth discrimination, including dual-energy (DE) imaging, tomosynthesis, and cone-beam CT (CBCT). Each represents a promising technology for diagnostic and image-guided procedures. In DE imaging, two images acquired at different x-ray energies are processed to yield images of bone or soft-tissue. In tomosynthesis and CBCT, the x-ray source and FPI move about the patient, and 3D images are reconstructed from multiple perspectives. Realizing the full potential of these modalities requires quantitative evaluation of imaging performance and a methodology for revealing the physical factors that limit image quality. Conventional Fourier-based metrics, such as Noise-Equivalent Quanta (NEQ), provide practical, prevalent figures of merit for spatial resolution and signal-to-noise ratio. For these advanced imaging modalities, however, there is currently no rigorous performance metrology (Fourier-based or otherwise); furthermore, the NEQ conventionally describes only the performance of the detector, and considers neither the structures of interest in the image (i.e., the task) nor the response of observers. This proposal pursues a fundamental image science approach to performance evaluation in these advanced modalities, breaking new ground in numerous respects: 1.) The NEQ and associated Fourier metrics are extended to each of the advanced modalities to provide an experimental and theoretical methodology for imaging performance evaluation; 2.) Structures of interest in the image are quantified in terms of the imaging t ask, considering a variety of simple and higher-order tasks (detection, localization, and size estimation) in relation to two of the most lethal cancers (lung carcinoma and liver metastases); and 3.) Quantitative formulations of imaging task and NEQ are rigorously combined to yield task-based metrics for imaging performance in DE imaging, tomosynthesis, and CBCT, and the extent to which such task-based metrics provide a meaningful surrogate for image quality is validated by correlation with the response of human observers. Hence, this proposal begins to bridge the gap between the prevalent Fourier-based approach and traditional observer-based approaches (e.g., ROC analysis) through rigorous quantitation of imaging task. For example, imaging performance in early detection of lung nodules is evaluated using Detection and Size Estimation tasks for DE imaging and tomosynthesis, while guidance of RF ablation or radiation therapy of liver metastases is evaluated in terms of a Localization task for CBCT. Successful completion of this program will offer a practical, task-driven approach to the design, evaluation, and optimization of these and other novel imaging modalities.