Purpose: A single-shot quantitative x-ray imaging (SSQI) method was previously demonstrated using simulation. The method quantifies material-specific densities using single-shot x-ray imaging by combining the use of a primary modulator (PM) and dual-layer (DL) detector. In this work, we performed a series of experiments on our benchtop system to test the robustness of SSQI for quantitative assessment.
Methods: The SSQI algorithm allows simultaneous recovery of two material decomposition and two scatter images using four sub-measurements from PM encoding. We first set up SSQI on our benchtop system and scanned acrylic and Cu slabs with known thicknesses (acrylic: [0 25] cm; Cu: [0 1] mm). We then estimated scatter with SSQI and compared the MD for different combinations of the two materials with ground truth. Second, we imaged an anthropomorphic chest phantom containing contrast in the coronary arteries and compared the MD with and without SSQI. Lastly, to evaluate SSQI in dynamic applications, we constructed a flow phantom that enabled dynamic imaging of iodine. The flow phantom was filled with a known concentration of iodine (150 mg/ml) at 10 ml/s using a power injector. Dynamic MD images were generated using SSQI.
Results: For the first validation study, the maximum root mean squared error (RMSE) of SSQI estimation for acrylic was 3.5% and less than 10% for most routinely used iodine concentrations. For the anthropomorphic phantom, direct MD resulted in incorrect interpretation of contrast and soft tissue, while SSQI successfully distinguished them. In the flow phantom, SSQI was able to perform accurate dynamic quantitative imaging, separating contrast from the background.
Conclusion: We further validated the concept of SSQI through experiments. The simplicity of SSQI may enable its widespread adoption, including radiography and dynamic imaging such as real-time image guidance and cone-beam CT.