Aiming at the problem of high-quality image reconstruction from projection data at sparse angular views, we proposed an improved fast iterative reconstruction algorithm based on the minimization of selective image total variation (TV). The new reconstruction scheme consists of two components. Firstly, the algebraic reconstruction technique (ART) algorithm was adopted to reconstruct image that met the identity and non-negativity of projection data, and then, secondly, the selective TV minimization was used to modify the above image. Two phases were alternated until it met the convergence criteria. In order to further speed up the convergence of the algorithm, we applied a fast convergence technology in the iterative process. Experiments on simulated Sheep-Logan phantom were carried out.The results demonstrated that the new method not only improved image reconstruction quality and protected the edge of the image characteristics, but also improved the convergence speed of the iterative reconstruction significantly.
ObjectiveTo explore the application of positron emission computed tomography (PET)/computed tomography (CT) in health physical examination. MethodsWe retrospectively analyzed the data of 1 515 people who underwent physical examination in West China Hospital of Sichuan University from January 2012 to November 2013. Demographic data and results of PET/CT scan were analyzed statistically. Follow-up was performed. ResultsTwenty-one cases of malignant tumors were found by PET/CT, including 7 cases of lung cancer, 5 of colon cancer (3 of sigmoid colon cancer, 1 of ascending colon cancer, and 1 of transverse colon cancer), 4 of thyroid carcinoma, 2 of nasopharyngeal carcinoma, 1 of prostate cancer, 1 of ovarian cancer, and 1 of other kind of cancer. All of them were confirmed after further examinations. ConclusionPET/CT has a positive significance in physical examination for some specific population.
In the design of oral cone beam CT, cooperation between synergic control of X-ray source, real-time acquisition of flat detector and motion of mechanical structure affects the CT image quality. Based on the full analysis of the flat detector's timing signal characteristics, this research was carried out with microprocessor controller (MCU), complex programmable logic device (CPLD), and light couplings to design and realize synchronous exposure control system. To evaluate whether the design of the synchronous exposure control system in this project could reach the required imaging accuracy, we employed the projected images in the system to analyze its stability, linear consistency, signal to noise ratio and precede the FDK construction.