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

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

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*

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

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

A retrospective study on 55 subjects with surrenal gland tumors diagnosed by CT showed that the tumors are commonly benign and pheocromocytoma was detected lately with a large size (> 3 cm, accounted for 73.5%). Heterogenous structure of the tumors before and after the injection of the contrasts showed characterustic sign of pheocromocytoma. The CT procedure has had a sensitivity of 100% and a positive predictive value of 89%. In the diagnosis of ganglion metastasis, these ratios were 2/3 and 99% respectively, in the evaluation of infiltration into the liver and the right kidney, these ratios were 58.30% and 95% respectively
Tomography, X-Ray Computed ; Neoplasms ; methods

In the load capacity test of CT diagnosis table top, by analyzing the easy destroy area and related test data for the table top, using a simple mechanical auxiliary support structure in local area of the table top to solve the insufficient loading strength problem of table top and obtain significant results during the actual product usage.
Tomography, X-Ray Computed ; instrumentation ; methods

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

It is the intent of this paper to develop better reconstruction algorithm for electrical impedance tomography (EIT). Simulation study of the reconstruction algorithm based on the sensitivity theorem is made and the reconstruction algorithm is compared with other normal algorithms. The results indicate that sensitivity method as a kind of static reconstruction algorithm has higher accuracy and speed of iteration, so it is worth researching for laboratory modality work.
Algorithms ; Computer Simulation ; Electric Impedance ; Tomography ; methods