ABSTRACT
<p><b>OBJECTIVE</b>To validate the efficiency and accuracy of an improved Demons deformable registration algorithm and evaluate its application in contour recontouring in 4D-CT.</p><p><b>METHODS</b>To increase the additional Demons force and reallocate the bilateral forces to accelerate convergent speed, we propose a novel energy function as the similarity measure, and utilize a BFGS method for optimization to avoid specifying the numbers of iteration. Mathematical transformed deformable CT images and home-made deformable phantom were used to validate the accuracy of the improved algorithm, and its effectiveness for contour recontouring was tested.</p><p><b>RESULTS</b>The improved algorithm showed a relatively high registration accuracy and speed when compared with the classic Demons algorithm and optical flow based method. Visual inspection of the positions and shapes of the deformed contours agreed well with the physician-drawn contours.</p><p><b>CONCLUSION</b>Deformable registration is a key technique in 4D-CT, and this improved Demons algorithm for contour recontouring can significantly reduce the workload of the physicians. The registration accuracy of this method proves to be sufficient for clinical needs.</p>
Subject(s)
Algorithms , Four-Dimensional Computed TomographyABSTRACT
<p><b>OBJECTIVE</b>To design a new afterloading brachytherapy simulation system based on CT images.</p><p><b>METHODS</b>This paper mainly focuses on the anthropomorphic pelvic phantom spiled by three pipelines and the nasopharyngeal carcinoma spiled by two pipelines. Microsoft Visual C++ was used to parse CT images for some information, then to reconstruct pipelines in the body of phantom or the patient and to give the three-dimensional coordinate of dwelling points. The dose distribution displayed on CT images was processed by the dose distribution calculation methods near single afterloading source and the dose optimization methods. VTK technology was used in the 3D display in the system.</p><p><b>RESULTS</b>According to the reference points applied by doctors, the system can calculate reversely the dwelling time of dwelling points in pipelines and get satisfying dose distribution on CT images. Besides, it can reflect the 3D relationship between the dose volume and the normal tissues.</p><p><b>CONCLUSIONS</b>This system overcomes some deficiencies of 2D afterloading brachytherapy simulation system based on X-ray films which are used widely in China. It supplies 3D display of dose distribution for clinical doctors. At present, the system is being tested in clinics.</p>
Subject(s)
Brachytherapy , Methods , Computer Simulation , Imaging, Three-Dimensional , Software , Tomography, X-Ray ComputedABSTRACT
<p><b>OBJECTIVE</b>To establish a method for efficient induction and expansion of Epstein Barr virus (EBV)-specific cytotoxic T lymphocytes (CTL) in vitro and evaluate the possibility of using this strategy for treatment of nasopharyngeal carcinoma (NPC).</p><p><b>METHODS</b>EBV-transformed B lymphoblastoid cells (BLCLs) were used as the antigen stimuli and antigen-presenting cells. EBV-specific CTL was induced by co-culture of the autologous peripheral blood mononuclear cells (PBMCs) and the irradiated BLCLs, and expanded with a cocktail method consisting of OKT-3, irradiated homologous PBMC, and IL-2. The specific activity of the CTL against the NPC cells was measured with MTT assay.</p><p><b>RESULTS</b>EBV-specific CTL was successfully induced and expanded by 600 folds. The killing efficiency of the CTL was 76% for autologous BLCLs, 13% for homologous BLCLs, 51% for autologous NPC cells, and 27% for homologous CNE cell line, and after expansion, the corresponding killing efficiencies were 63%, 25%, 49%, and 33%, respectively. The non-specific killing only slightly increased after the expansion.</p><p><b>CONCLUSION</b>EBV-specific CTL can be successfully induced and expanded in vitro for specific killing of autologous NPC cells, suggesting the potential of this strategy in the treatment of NPC.</p>