How to determine detection performance of a DPC-CT system from a conventional cone beam CT system?

Abstract

Although the relative ease of implementation and compact nature of grating-based differential phase contrast CT (DPC-CT) has sparked tremendous enthusiasm for potential medical applications, the pros and cons of this imaging method remains to be addressed before an actual clinical system can be constructed. To address these unknowns, either numerical simulations or direct hardware implementations can be used. However, both approaches have their limitations. It is highly desirable to develop a research method to enable imaging performance prediction for a future DPC-CT system from the performance of an available absorption CT (ACT) system. In this paper, a theoretical framework was developed to accurately predict the noise properties and detection performance of DPC-CT from that of conventional ACT. The framework was derived based on a fundamental noise relationship between DPC-CT and ACT and was experimentally validated. An example has been given in the paper on how the framework can be utilized to predict model observer detectability index of a DPC breast CT constructed based on an existing absorption breast CT. This framework is expected to become a valuable tool in addressing the following questions: (i) With a fixed radiation dose in a particular clinical application, how well can a specific detection/discrimination imaging task can be performed provided that an existing ACT scanner is modified into a DPC-CT by inserting a grating interferometer, which is characterized by a few design parameters (e.g., pitches and duty cycles of the gratings, relative distance between the gratings, etc.) into the ACT system? (ii) If a DPC-CT system can outperform an ACT for certain detection/discrimination tasks under the constraint of identical radiation dose to the image object, how would one optimize design parameters of the gratings in order to maximize its potential clinical benefits?