Quantitative CT Imaging for Response Assessment when using Dose Reduction Methods

描述（由申请人提供）：尽管人们普遍担心辐射剂量，但在许多临床试验中，CT仍被广泛用于评估治疗反应。在降低CT辐射剂量方面已经取得了重大进展，包括迭代重建技术、检测器技术和其他技术的进步，这些技术有望在保持临床图像质量的同时，显著降低患者的剂量（50- 60%）。虽然这些技术应该尽可能在临床环境中进行研究，但它们对从CT图像中提取的定量测量的影响尚不清楚，需要在临床试验中部署之前进行研究。简单地降低管电流时间积（mAs）会增加图像噪声，从而增加定量测量的可变性。根据解剖区域的不同，尺寸测量可能受到不同的影响；肺部病变（通常是高对比度物体）可能与肝脏病变（通常是高对比度物体）的影响不同

DESCRIPTION (provided by applicant): Despite widespread concerns over radiation dose, CT continues to be widely used for assessing response to therapy in many clinical trials settings. There have been significant developments which allow the reduction of radiation dose from CT, including advances in iterative reconstruction techniques, detector technologies and others that promise significant dose reductions (50-60 percent) to patients, while maintaining clinical image quality. While these technologies should be investigated wherever possible in a clinical environment, their effects on quantitative measures extracted from CT images are unclear and need to be investigated before they are deployed in clinical trials. Simply reducing tube current time product (mAs) will increase image noise, which may increase variability in quantitative measures. Size measures may be affected differently depending on the anatomic region; lung lesions (typically high contrast objects) may be affected differently from liver lesions (typically lower contrast). Peak values measured when contrast enhanced studies are used may also respond to dose reductions differently. In addition, because new iterative reconstruction methods reduce noise, they often also smooth the image somewhat, which may affect size and density (e.g. average HU) measures. Therefore, this application proposes to systematically investigate the effects of radiation dose reduction methods on quantitative metrics used in clinical trials. The goal is to determine how far we can decrease dose under different conditions before we increase variance to unacceptable levels in the context of clinical trials using quantitative measures to assess response to therapy. We have proposed three specific aims to carry out this research. In the first aim, we propose to create a collection of cases that represen a range of low dose acquisition and reconstruction scenarios in specific quantitative imaging tasks. This will be accomplished using a calibrated dose reduction simulation method (noise insertion tool) and then reconstructing images under a wide variety of dose reduction levels and reconstruction methods. The second specific aim will be to extract quantitative Imaging measures from these reconstructed image data sets and analyze variance of quantitative measures across dose levels and reconstruction methods. The third will use the results of the second aim's analysis to evaluate reduced dose imaging effects in a prospective clinical trial. The overall goal is to provide guidance to the QIN, and clinical trials in general, regarding the use of both standardized protocols and the use of dose reduction methods, with the ultimate goal of determining the levels of dose reduction that yield acceptable levels of measurement variance in several assessment tasks/environments.