Determination of calibration parameters of a VRX CT system using an "Amoeba" algorithm

Area of Science:

• Medical Imaging
• Physics
• Engineering

Background:

• Current CT scanner resolution improvements primarily focus on hardware, neglecting the "physics limit" imposed by secondary-ionization charge clouds.
• This limitation restricts the achievable spatial resolution in computed tomography (CT) imaging.

Purpose of the Study:

• To implement and validate "projective compression," a technique to overcome the physics limit and enhance CT spatial resolution.
• To develop and calibrate a dual-arm "variable-resolution x-ray" (VRX) detector for implementing projective compression.

Main Methods:

• Projective compression was realized using a dual-arm VRX detector, where apparent cell size is smaller than physical cell size.
• Calibration involved scanning a rotating pin and fitting a theoretical curve to the pin sinogram using multi-parameter minimization.
• The fitting process assessed fit convergence and sensitivity to initial conditions.

Main Results:

• Excellent fits were achieved for both detector arms, with average and maximum deviations of ~0.05 and 0.1 detector cell widths, respectively.
• The calibration process successfully provided accurate geometrical parameters for the VRX detector.
• Demonstrated pre- and post-optimization reconstructions of an alignment pin and a biological subject.

Conclusions:

• Projective compression offers a viable method to significantly boost CT spatial resolution beyond the conventional physics limit.
• The calibrated VRX detector effectively implements projective compression, enabling enhanced image reconstruction for CT techniques.