Lung cancer is the leading cause of death among the tumors in the whole world. Although new diagnostic techniques have been developed for nearly 20 years, the mortality is still high. Until now, no randomized controlled trial of chest x-ray and sputum cytology showed the improvement of the survival rate of lung cancer. Low-dose CT can screen more patients in early stage, however, overdiagnosis, cost and the quality of studies should be considered. Further studies of RCTs should be done to clarify these questions.
Objective To discuss the application of dual-source computed tomography （CT） low dose technology in the upper abdomen enhanced inspection. Methods Six hundred consecutive patients from July 2011 to February 2012 in this hospital were orderly divided into ordinal tube current （210 mAs） group and low dose tube current group （200 mAs，190 mAs，180 mAs，170 mAs，and 165 mAs）. The standard deviation （SD） of subcutaneous fat，signal to noise ratio （SNR） of liver and pancreas， contrast to noise ratio （CNR） of liver-erector spinae and pancreas-erector spinae，score of subjective diagnosis and the indexes of radiation dose，including CT dose index （CTDI），dose length product （DLP），effective dose （ED） were measured，calculated，and assessed respectively on CT images of arterial phase and portal phase from each group. Results The SD of subcutaneous fat， SNRs of liver and pancreas，score of subjective diagnosis，and the CTDI，DLP，ED of CT images in arterial phase and portal phase were significantly different from each other （P＜0.05），while CNRs of liver-erector spinae and pancreas-erector spinae were not statistically significant （P＞0.05）. The SNR，radiation dose，and score of subjective diagnosis of the 165 mAs tube current group were the lowest among all the groups，but the images of the 165 mAs tube current group could not fulfill the need of diagnosis. Conclusions It is really feasible that the method of decreasing tube current gradually in the upper abdomen enhanced CT inspection could ensure that the radiologists could adapt the low dose image bit by bit，and this methods could be popularized to all kinds of CT facilities we own currently. The images with 170 mAs as tube current in the upper abdomen enhanced inspection of dual-source CT could fulfill the need of diagnosis，and the radiation dose of patients is apparently lower than that the conventional scan．
目的 探讨双源CT腰椎检查中低剂量扫描方法及其临床应用价值。 方法 将2011年8月－2012年5月行双源CT腰椎检查的714例患者随机分为7组。均采用管电压120 kV，分别依次采用常规参考管电流量250 mAs和低管电流量240、230、220、210、200、190 mAs，且均采用CARE DOSE技术采集数据。扫描参数：准直器64 mm×0.6 mm，重建层厚0.75 mm，重建间隔0.7 mm，FOV 180～200 mm。采集图像后，测量腰3椎体的CT值及同层面的脊髓的CT值、背脊肌的CT值及噪声；腰5椎体的CT值及同层面的脊髓的CT值、背脊肌的CT值及噪声，并计算腰3、腰5椎体及相应层面脊髓的信噪比(SNR)和其相对于背脊肌的对比噪声比（CNR）。应用统计学软件对不同管电流下的CNR、SNR、盲法评分的数值以及射线剂量指数（CTDI）、剂量长度乘积（DLP）、有效剂量（ED）进行分析。 结果 第1组和第2组比较，图像的背脊肌SD值；腰3、腰5椎体和脊髓的SNR值进行比较，差异无统计学意义（P＞0.05）。第1组与第3、4、5、6、7组比较，腰3、腰5低管电流量各组间图像的背脊肌SD值；腰3、腰5椎体和脊髓的SNR值与常规管电流量组间比较差异均有统计学意义（P＜0.05）。腰3和腰5各组图像的椎体-背脊肌和脊髓-背脊肌CNR值分别行单因素方差分析，结果差异均无统计学意义（P＞0.05）。 结论 双源CT腰椎检查时，通过阶段性逐步降低管电流量的方法，使诊断医生逐渐适应低剂量图像质量，从而实现现有设备的低剂量扫描的方法是可行的。对于体质量指数（BMI）≤25 kg/m2的患者，可以采用190 mAs的参考管电流量进行腰椎扫描，不仅降低了患者接受的辐射剂量，同时也能获得满足临床诊断的合格图像，并且保护患者和减小设备损耗。
Objective To explore feasibility and clinical value of low dose computed tomography perfusion imaging (CTPI) in quantitative assessing proximal gastric cancer. Methods A total of 34 patients diagnosed with proximal gastric cancer (a proximal gastric cancer group) were enrolled prospectively in this study. The 25 normal parts of gastric fundus of the included patients constituted a control group. All the patients underwent the low dose CTPI before surgery. The total effective radiation dose was recorded, and a specific post-processing software was used to automatically generate the perfusion parameters values, including the time to peak (TTP), blood flow (BF), blood volume (BV), mean transmit time (MTT), and permeability (PMB). The perfusion parameters in the different histopathologic types and stages of the patients were compared. Receiver operating characteristic (ROC) curves were generated to compare their diagnosis performances. Results The histopathologic findings verified that there were 11 patients with T1+T2 stage and 23 patients with T3+T4 stage; 8 patients with signet ring cell carcinoma and 26 patients with adenocarcinoma; and 17 patients with lymphatic metastasis and 17 patients without lymphatic metastasis. ① Compared with the control group, the BF, BV, and PMB values were significantly higher and the MTT and TTP values were significantly lower in the proximal gastric cancer group. The area under the ROC curve (AUC) values of the BF, BV, PMB, MTT, and TTP in the diagnosing proximal gastric cancer was 0.955, 0.807, 0.987, 0.654, and 0.649 respectively. The BF and PMB represented the best diagnostic performances, and the BV was secondary in the ROC curve results. ② The BF value was significantly lower and the PMB value was significantly higher in the patients with signet ring cell carcinoma as compared with the patients with adenocarcinoma. However, the BV, MTT, and TTP values had no significant differences in both them. And the BF (AUC=0.986) had a better ability than the PMB (AUC=0.856) in the discriminating the histopathological type (P=0.047). ③ The PMB value in the patients with pathological stage T3 and T4 was significantly higher than that of the patients with pathological stage T1 and T2 (P=0.004), but the BF, BV, MTT, and TTP values had no differences in both them. The diagnosis value of the PMB in the discriminating the pathological stage was good with an AUC value of 0.814. ④ None of the parameters had significant difference between the patients with and without lymphatic metastasis (P>0.05). ⑤ The total effective radiation dose of each scan was 8.58 mSv, which was lower than that of the standard radiation dose of CTPI. ⑥ The rates of lymphatic metastasis and high T staging were not related to the histopathological type of the proximal gastric cancer (P>0.05). Conclusion Low dose CTPI used in this study could effectively reduce radiation dose, could quantitatively evaluate angiogenesis in proximal gastric cancer, and has a certain clinical value in identifying of histopathological type and evaluating of pathological stage.
Liver computed tomography (CT) perfusion is a noninvasive imaging technology which can quantitatively investigate liver function, and it is mainly used in the diagnosis of liver tumors and assessment of liver function in the state of chronic liver diseases. The use of liver CT perfusion was limited in the past because of the high radiation dose. Now new technologies are exploited and they make it possible to reduce the radiation burden while maintaining the imaging quality. This article discusses the research progress of low radiation dose CT perfusion in 3 aspects, including X-ray source, reconstruction algorithm, and improvement of CT scanners and optimization of scanning parameters. Although there are not too many studies of low radiation dose CT perfusion on liver now and many problems need to be solved, the clinical application of it will be very prospective.
目的 探讨双源CT低剂量扫描技术在胸部普通检查中的应用价值。 方法 将2011年8月－2012年12月收治的875例患者依次分为7组，分别采用常规管电流量110 mAs和低管电流量105、100、95、90、85、80 mAs测量，计算并评估7组患者纵隔窗图像的胸骨前空气CT值标准差（SD空气）、肺动脉分叉平面肺动脉信噪比、降主动脉信噪比、肺动脉-竖脊肌对比噪声比、降主动脉-竖脊肌对比噪声比；纵隔窗图像和肺窗图像主观质量评分以及射线剂量指标：CT剂量指数（CTDI）、剂量长度乘积（DLP）、有效剂量（ED）。 结果 7组患者纵隔窗图像肺动脉信噪比、降主动脉信噪比、图像主观质量评分和射线剂量CTDI、DLP、ED之间差异均有统计学意义（P＜0.05）；肺动脉-竖脊肌对比噪声比、降主动脉-竖脊肌对比噪声比之间差异无统计学意义（P＞0.05）；其中第7组图像信噪比、射线剂量和主观质量评分均为最低，部分图像肩背部出现横条状伪影，影响肺尖部病变的显示，难以提供足够的诊断信息。 结论 胸部普通CT检查，通过阶段性降低管电流量使诊断医生逐渐适应低剂量图像质量，从而普及现有设备的低剂量扫描的方法是可行的。双源CT采用85 mAs的参考管电流量，既能获得满足临床诊断的合格图像，又能明显降低患者群体接受的辐射剂量。
Objective To investigate the efficacy of low-dose inhaled nitric oxide (iNO) in the treatment of severe hypoxemia after Sun’s operation. Methods The clinical data of patients undergoing Sun’s operation for acute Type A aortic dissection in our hospital from January 2020 to June 2022 were retrospectively analyzed. Patients who received conventional treatment before November 2021 were enrolled as a control group. After November 2021, iNO was used in our hospital, and the patients who received iNO as an iNO group. The preoperative clinical baseline data, perioperative clinical data and oxygenation index were compared between the two groups. Results A total of 54 patients were included in the control group, including 45 males and 9 females, with an average age of 53.0±10.9 years. A total of 27 patients were included in the iNO group, including 21 males and 6 females, with an average age of 52.0±10.6 years. The preoperative body mass index of the two groups was greater than 25 kg/m2, white blood cell count, C-reactive protein were significantly higher than normal level, but there was no statistical difference between the groups (P＞0.05). There were no statistical differences in intraoperative data between the two groups (P＞0.05). The iNO group had significantly shorter duration of mechanical ventilation, postoperative ICU stay, and postoperative hospital stay than the control group (P<0.001). After 12 h of iNO treatment, hypoxic condition improved obviously, oxygenation indices in 12 h, 24 h, 36 h,48 h, 60 h and 72 h in the iNO group were significantly higher than those in the control group (P<0.05). Conclusion The treatment of severe hypoxemia after Sun’s surgery with low-dose of iNO is safe and effective, can significantly improve oxygenation function, and has significant advantages in shortening ventilator use time, postoperative ICU stay and postoperative hospital stay, but it is not significant in changing postoperative mortality.
ObjectivesTo investigate the influence of scanning parameters (tube voltages and tube currents) on image quality and corresponding radiation doses with simulated lung nodules in chest CT.MethodsThe anthropomorphic chest phantoms with 12 simulated, randomly placed nodules of different diameters and densities in the chest were scanned by different scanning parameters. The detection rate, degree of nodular deformation, image quality (with both subjective and objective evaluation) and the corresponding radiation doses were recorded and evaluated, and the correlation between nodule detection rate, degree of nodular deformation, radiation dose and image quality using different scanning parameters was analyzed.ResultsThe image quality improved with the increase of tube voltage and tube current (P<0.05). When the tube current was constant, the CT values of the vertebral decreased gradually with the increase of tube voltages (P<0.05); however, significant difference was not detected in CT values of the lung field (P>0.05). When the tube current was 100 mAs, the lung nodules with CT values of +100 HU and −630 HU showed statistical difference when using different tube voltage (P<0.05); but there was no significant difference in nodules of −800 HU (P=0.57). When tube voltage was 100 kV and 120 kV each, it was possible to detect all lung nodules with a detection rate of 100%. The detection rate was 33% and 66% in 3 mm diameter when the tube current was 80 kV/15 mA and 80 kV/20 mA, respectively. The nodules deformation in nodules with a CT value of −630 HU and diameter less than 5 mm was the most prominent (P<0.05). After analyzing the relationship between image quality and radiation doses using different tube voltages, we established a system of correlation equations: 80 kV: Y=2.625X+0.038; 100 kV: Y=14.66X+0.158; 120 kV: Y=18.59X+0.093.ConclusionsThe image quality improves with the increase of tube current and tube voltage, as well as the corresponding radiation doses. By reducing the tube voltage and increasing the tube current appropriately, the radiation doses can be reduced. Follow-up CT examination of pulmonary ground glass nodules should apply the same tube voltage imaging parameters, so as to effectively reduce the measurement error of nodule density and evaluate the change of nodules more accurately.
Objective To assess the radiation dose and image quality with low-dose multi-detector row CT urography （CTU） for the evaluation of children patients with ureteropelvic junction stenosis （UJS）. Methods In this prospective study， 30 children patients with UJS underwent CTU were classified half-randomly through exam numbers into 3 groups （115 mA， 100 mA， and 75 mA）. Consecutive acquisitions including CT dose index weighted （CTDIw） and dose long product （DLP） were obtained in each patient and compared for each group. Three experienced chest radio-logists were unaware of the CT technique reviewed CT images for overall image quality using a 3-grade scale （excellent， good， and worst）. The data were analyzed using a parametric analysis of variance test and Wilcoxon’s signed rank test. Results The CTDIws of 115 mA group， 100 mA group， and 75 mA group were （7.63±0.83） mGy， （6.29±0.51） mGy， and （4.72±0.18） mGy， respectively， the difference was significant among three groups （F=36.445， P=0.000）. The mean CTDIw reduction was 38.2% in the 75 mA group as compared with 115 mA group （P＜0.001）. The DLPs of 115 mA group， 100 mA group， and 75 mA group were （173.89±29.88） mGy•cm， （145.96±26.21） mGy•cm， and （102.78±12.72） mGy•cm， respectively， the difference was significant among three groups （F=13.955， P=0.000）. The mean radiation dose reduction was 40.9% （75 mA group versus 115 mA group， P＜0.001）. The assessment of image quality was no significant difference with the same protocol and post-processing technique （Wilcoxon’s signed rank test， P＞0.05）. There was a good agreement for image quality scoring among the three reviewers （Kappa=0.736）. Conclusion Low-dose multi-detector row CTU should be considered as a promising technique for the evaluation of children patients with UJS because it could decrease radiation dose and obtain acceptable image quality.
Considering the survival rate of small animals and the continuity of the experiments, high-dose X-ray shooting process is not suitable for the small animals in computed tomography (CT) experiments. But the low-dose process results with images might be polluted by noises which are not conducive for the experiments. In order to solve this problem, we in this paper introduce a global dictionary learning based denoising method to apply the promotion of the low dose CT image. We at first adopted the K-means singular value decomposition (K-SVD) algorithm to train a global dictionary based on the high dose CT image. Then, the noise image could be decomposed into sparse component which was free from noise through the orthogonal matching pursuit (OMP) algorithm. Finally, the noise-free image could be achieved by reconstructing the image only with its sparse components. The experiments results showed that the method we proposed here could decrease the noise efficiently and remain the details, and it would help promote the low dose image quality and increase the survival rate of the small animals.