Multi-slice spiral CT has been an outstanding progress in developmental history of CT technology. The technical indexes of all three respects, ie scanning range time and spatial resolution are all marked improved. And several robust post-processing techniques have been imported into CT data post-scanning reconstruction, which help massive volume data being sufficiently and optimally interpreted. Therefore, newer advances have been achieved both in clinical applications and diagnostic efficacy.
Tomography, Spiral Computed ; methods

Magnetoacoustic tomography (MAT) has some advantages such as high sensitivity and high spatial resolution. The generating mechanism of acoustic source is the research foundation of forward and inverse problems. A coustic signals were respectively simulated by using monopole and dipole radiation theory in the experimental conditions, then the differences between their acoustic pressures were discussed, and furthermore the contrast and validation were conducted by physical experiments in this study. The physical experimental results showed that acoustic waveform of MAT had a certain directivity and therefore they indicated that dipole model showed higher approximation to the real facts than monopole model. It can be well concluded that this research has cardinal significance for the accurate algorithm of MAT.
Acoustics ; Algorithms ; Tomography ; methods

As technologies are progressing rapidly in many aspects, microPET has been developing worldwide at present. The principle, up-to-date status and development of microPET, as well as its existing problems which should be solved, have been introduced in this paper.
Positron-Emission Tomography ; methods ; trends

OBJECTIVE: To build a helical CT projection data restoration model at random low-dose levels. METHODS: We used a noise estimation module to achieve noise estimation and obtained a low-dose projection noise variance map, which was used to guide projection data recovery by the projection data restoration module. A filtering back-projection algorithm (FBP) was finally used to reconstruct the images. The 3D wavelet group residual dense network (3DWGRDN) was adopted to build the network architecture of the noise estimation and projection data restoration module using asymmetric loss and total variational regularization. For validation of the model, 1/10 and 1/15 of normal dose helical CT images were restored using the proposed model and 3 other restoration models (IRLNet, REDCNN and MWResNet), and the results were visually and quantitatively compared. RESULTS: Quantitative comparisons of the restored images showed that the proposed helical CT projection data restoration model increased the structural similarity index by 5.79% to 17.46% compared with the other restoration algorithms (P < 0.05). The image quality scores of the proposed method rated by clinical radiologists ranged from 7.19% to 17.38%, significantly higher than the other restoration algorithms (P < 0.05). CONCLUSION The proposed method can effectively suppress noises and reduce artifacts in the projection data at different low-dose levels while preserving the integrity of the edges and fine details of the reconstructed CT images.
Algorithms ; Artifacts ; Tomography, Spiral Computed ; Tomography, X-Ray Computed/methods*

This paper introduced the imaging principle, data acquisition method and image characteristics of PET/CT; Then reviewed several image reconstruction methods widely used in PET/CT at present in detail, such as FBP, ML-EM, 3DRP and so on. Finally, the advantages and disadvantages of these methods were summarized and compared.
Image Interpretation, Computer-Assisted ; methods ; Positron-Emission Tomography ; methods ; Tomography, X-Ray Computed ; methods

The applications of PET-CT have developed from qualitative analysis to quantitative analysis. Target volume is important for tumor biological volume defining, tumor isotope therapy, organ function evaluation, acceptor affinity calculation, and pharmaceutical metabolic kinetics. Many factors work on the target volume calculation, such as PET image acquisition mode, scatter correction, attenuation correction, reconstruction method, image display mode, positron pharmacy. The commonly-used methods of target volume calculation are background-threshold, max threshold, and background-max threshold. In this article we will discuss about the methods of target volume calculation.
Algorithms ; Positron-Emission Tomography ; methods ; Radiotherapy Planning, Computer-Assisted ; methods ; Tomography, X-Ray Computed ; methods

A digital system for bioimpedance and electrical impedance tomography (EIT) measurement controlled by an ATmega16 microcontroller was constructed in our laboratory. There are eight digital electrodes using AD5933 to measure the impedance of the targets, and the data is transmitted to the computer wirelessly through nRF24L01. The structure of the system, circuit design, system testing, vitro measurements of animals' tissues and electrical impedance tomography are introduced specifically in this paper. The experimental results showed that the system relative error was 0.42%, and the signal noise ratio was 76.3 dB. The system not only can be used to measure the impedance by any two electrodes within the frequency of 1-100 kHz in a sweep scanning, but also can reconstruct the images of EIT. The animal experiments showed that the data was valid and plots were fitting with Cole-Cole theory. The testing verified the feasibility and effectiveness of the system. The images reconstructed of a salt-water tank are satisfactory and match with the actual distribution of the tank. The system improves the effectiveness of the front-end measuring signal and the stability of the system greatly.
Animals ; Electric Impedance ; Electrodes ; Tomography ; methods

In this paper, a variation function has been introduced as a regularization penalty term in electrical impedance tomography (EIT) image restoration, which becomes to be the variation regularization algorithm. The key difference with Tikhonov regularization algorithm is that the variation regularization algorithm not only ensures the inverse problem well-posed but also increase the dividing line between the goal region and the background region of restored image clearer. This made the restored image in good accord with the medical image. It has significance to utilize EIT technique.
Algorithms ; Electric Impedance ; Humans ; Tomography ; methods

A fast non-local means image denoising algorithm is presented based on the single motif of existing computed tomography images in medical archiving systems. The algorithm is carried out in two steps of prepossessing and actual possessing. The sample neighborhood database is created via the data structure of locality sensitive hashing in the prepossessing stage. The CT image noise is removed by non-local means algorithm based on the sample neighborhoods accessed fast by locality sensitive hashing. The experimental results showed that the proposed algorithm could greatly reduce the execution time, as compared to NLM, and effectively preserved the image edges and details.
Algorithms ; Tomography, X-Ray Computed ; methods

Atherosclerosis ; diagnosis ; Humans ; Tomography, Optical Coherence ; methods