Online geometric calibration of a hybrid CT system for ultrahigh-resolution imaging

TL;DR

This paper presents an online geometric calibration method for a hybrid CT system with a detachable detector insert, enabling ultrahigh-resolution imaging by accurately aligning the insert with the scanner using fiducial markers and iterative registration.

Contribution

It introduces a novel iterative registration algorithm for real-time geometric calibration of a detachable detector insert in a hybrid CT system, improving image quality.

Findings

Achieved precise alignment of detector insert with the CT scanner.

Enhanced image resolution and reduced artifacts in chest scans.

Validated method with improved imaging accuracy.

Abstract

A hybrid imaging system consisting of a standard CT scanner and a low-profile photon-counting detector insert in contact with the patient's body has been used to produce ultrahigh-resolution images in a limited volume in chest scans of patients. The detector insert is placed on the patient bed as needed and not attached. Thus, its position and orientation in the scanner is dependent on the patient's position and scan settings. To allow accurate image reconstruction, we devised a method of determining the relative geometry of the detector insert and the CT scanner for each scan using fiducial markers. This method uses an iterative registration algorithm to align the markers in the reconstructed volume from the detector insert to that of the concurrent CT scan. After obtaining precise geometric information of the detector insert relative to the CT scanner, the two complementary sets of images are summed together to create a detailed image with reduced artifacts.