Geometry calibration and image reconstruction for carbon-nanotube-based multisource and multidetector CT

Abstract

Conventional intraoperative computed tomography (CT) has a long scan time, degrading the image quality. Its large size limits the position of a surgeon during surgery. Therefore, this study proposes a CT system comprising of eight carbon-nanotube (CNT)-based x-ray sources and 16 detector modules to solve these limitations. Gantry only requires 45° of rotation to acquire the whole projection, reducing the scan time to 1/8 compared to the full rotation. Moreover, the volume and scan time of the system can be significantly reduced using CNT sources with a small volume and short pulse width and placing a heavy and large high-voltage generator outside the gantry. We divided the proposed system into eight subsystems and sequentially devised a geometry calibration method for each subsystem. Accordingly, a calibration phantom consisting of four polytetrafluoroethylene beads, each with 15 mm diameter, was designed. The geometry calibration parameters were estimated by minimizing the difference between the measured bead projection and the forward projection of the formulated subsystem. By reflecting the estimated geometry calibration parameters, the projection data were obtained via rebinning to be used in the filtered-backprojection reconstruction. The proposed calibration and reconstruction methods were validated by computer simulations and real experiments. Additionally, the accuracy of the geometry calibration method was examined by computer simulation. Furthermore, we validated the improved quality of the reconstructed image through the mean-squared error (MSE), structure similarity (SSIM), and visual inspections for both the simulated and experimental data. The results show that the calibrated images, reconstructed by reflecting the calibration results, have smaller MSE and higher SSIM values than the uncalibrated images. The calibrated images were observed to have fewer artifacts than the uncalibrated images in visual inspection, demonstrating that the proposed calibration and reconstruction methods effectively reduce artifacts caused by geometry misalignments.

New progress in tumor treatment based on nanoparticles combined with irreversible electroporation

“…[48][49][50] Besides, CNTs have the characteristics of electric field response, [51,52] and the development of combined treatment with IRE is significant. [53,54] According to the research results of Mao et al [55] CNTs have unique tumor targeting and local electric field amplification ability. Thereby, CNTs were combined with low-intensity nanosecond electric pulses (nsEPs).…”

“…In other research directions, some scholars have fabricated CNTs into targeted molecular probes for tumor diagnosis, combined with -X-ray, Computed tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Computed Tomography (PET-CT), and other imaging equipment for targeted ablation and -post-treatment evaluation of tumors. [54,[64][65][66][67] Saghatchi F et al [68] have made preliminary exploration in this direction and made some achievements. Their previous research found that MWCNTs functionalized with magnetic Fe 3 O 4 and gold nanoparticles (AU-NPs) can act as contrast agents in CT scanning and ultrasonic imaging.…”

Online Calibration of a Linear Micro Tomosynthesis Scanner

“…As a brief review of the literature, there is a wealth of calibration methods for cone-beam computed tomography (CT) and tomosynthesis imaging in diverse applications [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. They can broadly be separated into offline phantom-based calibration methods and online phantom-less methods [ 39 ].…”

Online Geometric Calibration of a Hybrid CT System for Ultrahigh-Resolution Imaging

“…The hybrid CT system has a unique architecture and presents a unique geometric calibration problem, with a unique set of information that can be used for calibration. Previously, a number of calibration methods have been developed for cone-beam tomosynthesis as well as computed tomography to meet the demand of diverse applications [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. They have been generally classified into offline phantom-based calibration methods and online phantom-less methods [ 28 ].…”