ABSTRACT
Objective To explore a quality assurance testing method for gemstone spectral imaging (GSI)computed tomography. Methods A phantom prototype made of 9 bottles of pure water mixed with Iopamidol (300 mg I/mL)at different Iodine concentra-tions was scanned using the GSI mode under a routine head protocol on a GE Discovery CT750 HD scanner.Then the images were post-processed on a GE AW4.6 workstation.Results Based on the effective atomic number histogram,water & Iodine scatterplot and spectral HU curve,the Iodine solution concentrations of the phantom were not only differentiated but quantified.Conclusion It is feasible to test the material decomposition capability of GSI with the phantom prototype.
ABSTRACT
Objective To investigate the influence of physiological motions on three-dimensional (3D) CT images and the rules of motion artifacts.Methods A mathematical model of motion artifact was set up based on the principle of spiral scanning, hereby the geometrical distortion of 3D image was analyzed.Experiments were carried out with home-made phantoms on a CT scanner.Results The details of 3D images with trivial distortion were legible under static condition.On the contrary, distinct distortion occured under moving condition, and its degree increased with the pitch and motion period. The 3D images were varied with difference of the motion initial phases.Conclusion The distortion of 3D-CT image depends on the motion characters of scanned objects and scanning parameters such as pitch and slice thickness.
ABSTRACT
Objective To explore the theory and method of 4-dimensional (4D) imaging based on a spiral CT scanner. Methods The experiments were carried out on a Toshiba Asteion TSX-021A scanner with a motion phantom which consisted of a platform and some tumor-like plastic balls driven by a step-motor in sine mode to simulate respiration. The gantry rotation cycle, pitch and slice thickness were 1.5 s, 0.6 and 3 mm,respectively,according to radiotherapeutic application. Data processing including 3D image reformation and phantom centroid tracing were accomplished on a treatment planning system TOPLANE WiMRT V1.0. Results The phantom experiments demonstrated that the quality of a reformatted 3D image was better than that of a conventional reconstructed 3D image apparently for its less motion artifacts, and the measured centroid locus of the balls based on 4D imaging was closed to the actual motion process. Conclusion 4D imaging based on a single-slice spiral CT scanner is feasible.