The Effect of Extrinsic Material and Radiation Dose on Model-Based Iterative Reconstruction Chest Computed Tomography Reconstruction Time: A Phantom-Based Study.

ABSTRACT

OBJECTIVE: Compare effect of extrinsic materials and radiation dose levels on image processing times for model-based iterative reconstruction (MBIR) in computed tomography. METHODS: Chest computed tomography scans were performed on a phantom with three different levels of clothing and medical equipment at three tube current settings to reflect differing radiation doses. Reconstruction time for MBIR was recorded, and objective image quality was assessed via noise within the phantom mediastinum. Reconstruction time and noise were compared between scans, with noise also compared between MBIR and matching filtered back projection (FBP) images. RESULTS: Reconstruction times (minutesseconds) ranged from 3731 to 4224. Times were generally faster with less extrinsic material and prolonged among high-dose scans when materials were present. On both the MBIR and FBP images, noise levels were improved with higher radiation doses, although for MBIR only minimally, and the relative effect of extrinsic materials at a given radiation dose was also minimal. In addition, noise was better with MBIR than FBP reconstruction for all conditions. CONCLUSIONS: Typical MBIR reconstruction times are faster with less extrinsic materials in the scan field of views, and removing extraneous blankets or medical devices could positively affect workflow over the course of the day. In addition, MBIR reconstruction times are also shorter when using lower dose protocols in situations requiring extensive materials.