One algorithm is designed to implement longitudinal auto-tracking of the the detector on X-ray in the digital radiography system (DR) with manual collimator. In this study, when the longitudinal length of field of view (LFOV) on the detector is coincided with the longitudinal effective imaging size of the detector, the collimator half open angle (Ψ), the maximum centric distance (emax) between the center of X-ray field of view and the projection center of the focal spot, and the detector moving distance for auto-traking can be calculated automatically. When LFOV is smaller than the longitudinal effective imaging size of the detector by reducing Ψ, the emax can still be used to calculate the detector moving distance. Using this auto-tracking algorithm in DR with manual collimator, the tested results show that the X-ray projection is totally covered by the effective imaging area of the detector, although the center of the field of view is not aligned with the center of the effective imaging area of the detector. As a simple and low-cost design, the algorithm can be used for longitudinal auto-tracking of the detector on X-ray in the manual collimator DR.
This study proposed a method to calibrate tube focus spot and the center plane of rotation in computed tomography system. In the method, the tube was rotated to 0° and 180° respectively, and then one metal jig with symmetric windows A and B was scanned at each position under the tube cool and static condition. According to the geometry of tube focus spot, aperture center of the collimator and jig, the distance between tube focus spot and the center plane of rotation were calculated with the X ray transmittance data after denoising, mean value and normalization. To verify the practicability and validity of the method, the tube focus spot in a 16 slices CT system (Brivo CT385, GE, China) was calibrated, and the result after calibration was validated by scanning a polaroid film. The validation result showed that the deviation between tube focal spot and center plane of rotation was 0.02 mm and was in the error range within ± 0.1 mm. The results of this study showed that, as a simple and low-cost design, the method could be used for fast calibration between tube focus spot and the center plane of rotation.
ObjectiveTo conduct a Meta-analysis to determine the clinical effect of protocol biopsy (PB)-monitored therapy after renal transplantation.MethodsPubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang Standards Database and VIP Database for Chinese Technical Periodicals were searched for trials comparing the efficacy of timely intervention under PB surveillance with the conventional treatment. The quality of included studies was assessed and Meta-analysis was conducted by RevMan 5.3 software.ResultsSix randomized controlled trials met our inclusion criteria, including 698 cases. No significant difference was found between the PB group and the control group in 1-year [relative risk (RR)=0.99, 95% confidence interval (CI) (0.97, 1.01), P=0.39] and 2-year recipient survival rate [RR=1.00, 95%CI (0.97, 1.02), P=0.72]. Graft survival rate after 1 year [RR=1.01, 95%CI (0.99, 1.04), P=0.29] and 2 years [RR=1.02, 95%CI (0.99, 1.06), P=0.19] were also statistically similar. No statistical difference was found in glomerular filtration rate between the two groups [mean difference (MD)=0.45 mL/(min·1.73 m2), 95%CI (–3.77, 4.67) mL/(min·1.73 m2), P=0.83]. Renal function of PB group, monitored by serum creatinine, was superior to the control group [MD=–0.46 mg/dL, 95%CI (–0.63, –0.29) mg/dL, P<0.000 01]. No statistical difference was found in infection between the two groups [RR=1.23, 95%CI (0.69, 2.19), P=0.48].ConclusionsOur study did not suggest PB for every kidney transplantation recipient. However, long-term randomized controlled trials with larger sample size would be necessary to determine whether PB was effective for specific populations.
Objective To discuss the safety and validity of pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH) patients with severe right heart failure (RHF). Methods PEA procedures were performed on 36 patients in Fu Wai Hospital from January 2015 to April 2016. There were 28 males and 8 females, with a mean age of 46.56±11.85 years. According to the New York Heart Association (NYHA) cardiac function classification, 36 patients were divided into preoperative severe RHF group (grade Ⅲ-Ⅳ,n=28) and preoperative without severe RHF group (grade Ⅱ,n=8). Hemodynamic parameters before and after PEA were recorded and 3-18 months' follow-up was done. Results All the patients having PEA surgeries had an obvious decrease of mean pulmonary arterial pressure (from 49.53±13.14 mm Hg to 23.58±10.79 mm Hg) and pulmonary vascular resistance (from 788.46±354.60 dyn·s/cm5 to 352.89±363.49 dyn·s/cm5, bothP<0.001). There was no in-hospital mortality among all the patients. Persistent pulmonary hypertension occurred in 2 patients, perfused lung in 2 patients, pericardial effusion in 2 patients. No mortality was found during the follow-up period. All patients improved to NYHA grade Ⅰ-Ⅱ (WHO grade Ⅰ-Ⅱ), and only 2 patients remained in the NYHA grade Ⅲ (P<0.01). Conclusion The CTEPH patients having PEA surgeries had an obvious improvement in both their hemodynamics results and postoperative heart function, which in return could improve their quality of life.