Deep-Learning Driven Noise Reduction for Reduced Flux Computed Tomography

TL;DR

This paper demonstrates how deep neural networks can enhance micro-CT images of geomaterials, reducing exposure times by over 60% while maintaining image quality, with transfer learning and different loss functions evaluated.

Contribution

It introduces a DCNN-based method for improving CT image quality of geomaterials and significantly reducing scan times, applicable across CT technologies.

Findings

DCNN improves micro-CT image quality of geomaterials.

Exposure times can be reduced by more than 60%.

Transfer learning enhances results without additional training time.

Abstract

Deep neural networks have received considerable attention in clinical imaging, particularly with respect to the reduction of radiation risk. Lowering the radiation dose by reducing the photon flux inevitably results in the degradation of the scanned image quality. Thus, researchers have sought to exploit deep convolutional neural networks (DCNNs) to map low-quality, low-dose images to higher-dose, higher-quality images thereby minimizing the associated radiation hazard. Conversely, computed tomography (CT) measurements of geomaterials are not limited by the radiation dose. In contrast to the human body, however, geomaterials may be comprised of high-density constituents causing increased attenuation of the X-Rays. Consequently, higher dosage images are required to obtain an acceptable scan quality. The problem of prolonged acquisition times is particularly severe for micro-CT based scanning technologies. Depending on the sample size and exposure time settings, a single scan may require several hours to complete. This is of particular concern if phenomena with an exponential temperature dependency are to be elucidated. A process may happen too fast to be adequately captured by CT scanning. To address the aforementioned issues, we apply DCNNs to improve the quality of rock CT images and reduce exposure times by more than 60\%, simultaneously. We highlight current results based on micro-CT derived datasets and apply transfer learning to improve DCNN results without increasing training time. The approach is applicable to any computed tomography technology. Furthermore, we contrast the performance of the DCNN trained by minimizing different loss functions such as mean squared error and structural similarity index.