ObjectiveTo improve health care quality and safety by monitoring the performance of PhilipsPrecedence Dual-head single photon emission computed tomography (SPECT). MethodsWith our own homemade point source and the center of rotation model, in accordance with NEMA standards and manufacturers' design conditions, these three indicators including energy peak position of the instrument, intrinsic uniformity and center of rotation were routinely tested between 2008 and 2012 for the Philips-Precedence Dual-head SPECT in our hospital. In addition, the quality control was performed twice a week, and every year the total number of quality control was basically the same. We calculated the results by the weighted average method. ResultsThe 5-year average energy peaks of detector 1 and 2 were (139.23±0.32) and (138.97±0.45) keV, respectively, and they were both within the range of reference values [(140±3) keV]. In addition, the results of center of rotation were also in the normal range, and kept stable. Based on the analysis of quality-control data, for detector 1, compared with the data of 2008, there was no significant diTherence for central field of vision (CFOV) and useful field of vision (UFOV) in these three years from 2009 to 2011 (P>0.05). The diTherence was only significant between data of 2008 and that of 2012 (P<0.05). For detector 2, compared with the data of 2008, there was no significant diTherence for CFOV and UFOV in 2009 and 2011(P>0.05), while there was significant diTherent in 2010 and 2012 (P<0.05). ConclusionThe uniformity of SPECT will gradually deteriorate with prolonged use. However, regular quality control and maintaining can keep the function stabilization, and enhance the availability rate.
ObjectiveTo evaluate the effectiveness of the single segmental cervical disc replacement with ProDisc-C, and to explore the location change of the flexion/extension center of rotation (COR) of the target level as well as its clinical significance. MethodsBetween June 2010 and February 2012, 23 patients underwent single segmental cervical disc replacement with ProDisc-C, and the clinical data were retrospectively analyzed. Of 23 patients, 9 were male, and 14 were female with the age range from 27 to 65 years (mean, 45 years), and the disease duration ranged from 10 to 84 months (mean, 25 months). There were 15 patients with radiculopathy, 5 patients with myelopathy, and 3 patients with mixed cervical spondylosis. The involved segments were C4,5 in 5 cases, C5,6 in 14 cases, and C6,7 in 4 cases. Japanese Orthopaedic Association (JOA) score and neck disability index (NDI) were adopted to evaluate the effectiveness. Preoperative and Postoperative radiographic parameters, such as cervical overall range of motion (ROM), target segmental ROM, the adjacent segmental ROM, and intervertebral height were compared. Besides, the location changes of the COR of the target level were further analyzed by the alteration of its coordinates (COR-X,COR-Y), and the relationships between the location changes of the COR and the effectiveness or the radiographic results were analyzed. ResultsAll the operations were completed successfully; 1 case had hoarseness after operation, which disappeared at 3 months after operation. All cases were followed up 18.3 months on average (range, 6-36 months). There was no device migration, loosening, subsidence, or fracture at last follow-up. The JOA score increased significantly and the NDI score decreased significantly at last follow-up when compared with preoperative scores (P<0.05). No difference was found in the cervical overall ROM, target segmental ROM, the adjacent segmental ROM, and the COR-Y of the target level between pre-operation and last follow-up (P>0.05); while the intervertebral height and the COR-X increased significantly (P<0.05). The change of the COR-X had no obvious correlation with the postoperative JOA, NDI, and target segmental ROM (P>0.05). According to whether the difference of the COR-X between pre- and post-operation was less than the average value 1.86 mm or not, the patients were divided into 2 groups; significant difference was shown in the postoperative target segmental ROM between 2 groups (P<0.05), but no significant difference was found in the postoperative JOA、NDI, cervical overall ROM, adjacent segmental ROM, and the intervertebral height between 2 groups (P>0.05). ConclusionSingle segmental cervical disc replacement with ProDisc-C can obtain satisfactory outcomes. The cervical overall ROM, target segmental ROM, and adjacent segmental ROM can be effectively maintained, and the intervertebral height is increased. The location of the flexion/extension COR of the target segment shifts forward after insertion of the ProDisc-C prosthesis, and the postoperative target segmental ROM becomes smaller as the distance of the displacement of the COR becomes greater.