ABSTRACT
Objective:To analyze and compare the X-ray procedures and radiation dose composition of ophthalmic inpatients, and to explore the changes of the X-ray examination mode in recent years and the effect of optimization in imaging technology on the radiation dose level of the patients.Methods:The simple random sampling method was used to retrospectively select the imaging data of the ophthalmic inpatients in the Second Affiliated Hospital of Zhejiang University School of Medicine from July 1st to November 31st in 2019 and from July 1st to November 31st in 2020. A total of 516 cases were selected according to the imaging time, including 258 cases in 2019 and 258 cases in 2020. Based on our previous research and the related documents of low-dose CT screening, a series of optimizations on CT scanning parameters and process were carried out in 2020, including the frequency of DR and CT scanning, the number of examinations per capita, the composition ratio of CT and DR, and X-ray dose per capita.Results:In 2020, the average effective doses of chest CT and orbital CT for ophthalmic inpatients were (2.587±1.586) mSv and (0.877±0.733) mSv, significantly lower than those in 2019 ( F=0.52, 0.72, P<0.05), and decreased by 34.82% and 37.13%, respectively. There was no significant difference in the average effective dose of chest DR and head CT between 2020 and 2019 ( F=6.01, 1.81, P>0.05). The number of X-ray examination per capita increased by 0.15 times, and the effective dose increased by 1.44 times (1.589 mSv). Chest DR was the main type of X-ray examination, accounting for 68.79% of all examinations in 2019, while chest CT was the main type, accounting for 71.05% in 2020. The composition of chest CT in 2020 increased by 63.17% compared with 2019, and the compositions of chest DR, orbital CT and cranial CT were decreased by 53.88%, 5.79% and 2.89%, respectively. Conclusions:With dose optimization measures, the single CT dose of ophthalmic inpatients in 2020 was lower than that in 2019. Chest CT increased significantly in frequency, and became main X-ray examination instead of chest DR which made the effective dose of ophthalmic inpatients increasing significantly.
ABSTRACT
Objective To investigate the reversibility of ischemic core defined by CT perfusion imaging in acute ischemic stroke (AIS) patients receiving intravenous thrombolysis within different time windows and influencing factors.Methods The data of AIS patients who received intravenous thrombolysis in the Department of Neurology of Lishui People's Hospital from May 2016 to December 2018 were retrospectively reviewed.All patients had finished multi-model CT imaging before thrombolysis and multi-model MRI examination 24-48 hours after thrombolysis.The baseline ischemic core volume (hypoperfusion area with relative cerebral blood flow (rCBF)＜30％) was quantitatively assessed based on CT perfusion images using MIStar software,and the final ischemic core volume was assessed based on diffusion weighted imaging acquired 24-48 hours after thrombolysis.The reversibility of ischemic core was defined as baseline ischemic core volume-the final infarct volume ≥5 ml.Then the clinical and imaging features of the patients between reversible group and irreversible group were compared,and the predictors of ischemic core reversibility were analyzed by binary Logistic regression analysis.Results Finally,97 patients were enrolled in the present study,of which 64 (66％) patients achieved successful recanalization,51 (53％) patients with reversible baseline ischemic core.For patients with recanalization,the incidence of reversibility was 76％ (26/34),71％ (17/24),2/5 and 0 (0/1) in patients with time window from onset to thrombolysis (ONT) ＜3.0 h,3.0-4.5 h,4.6-6.0 h,and ＞6.0 h,respectively.In the non-recanalization group,six patients were also showed with ischemic core reversibility,including 4 (4/12) in the ONT＜3.0 h group and 2 (2/12) in the ONT 3.0-4.5 h group.It was found that the reversible volume was positively correlated with baseline ischemic core volume (r=0.805,P＜0.001) by Spearman correlation analysis.Finally,binary Logistic regression analysis revealed that the history of hypertension,ONT and recanalization were independent predictors of reversible changes of baseline ischemic core.Conclusions The ischemic core defined by CT perfusion imaging (rCBF＜30％) was considerably inaccurate for patients with ONT＜6.0 h.If recanalization could be achieved within this time window,most of the patients would manifest with ischemic core reversibility,the predictors of which also included hypertension history and ONT.
ABSTRACT
Objective@#To investigate the reversibility of ischemic core defined by CT perfusion imaging in acute ischemic stroke (AIS) patients receiving intravenous thrombolysis within different time windows and influencing factors.@*Methods@#The data of AIS patients who received intravenous thrombolysis in the Department of Neurology of Lishui People′s Hospital from May 2016 to December 2018 were retrospectively reviewed. All patients had finished multi-model CT imaging before thrombolysis and multi-model MRI examination 24-48 hours after thrombolysis. The baseline ischemic core volume (hypoperfusion area with relative cerebral blood flow (rCBF)<30%) was quantitatively assessed based on CT perfusion images using MIStar software, and the final ischemic core volume was assessed based on diffusion weighted imaging acquired 24-48 hours after thrombolysis. The reversibility of ischemic core was defined as baseline ischemic core volume-the final infarct volume ≥5 ml. Then the clinical and imaging features of the patients between reversible group and irreversible group were compared, and the predictors of ischemic core reversibility were analyzed by binary Logistic regression analysis.@*Results@#Finally, 97 patients were enrolled in the present study, of which 64 (66%) patients achieved successful recanalization, 51 (53%) patients with reversible baseline ischemic core. For patients with recanalization, the incidence of reversibility was 76% (26/34), 71% (17/24), 2/5 and 0 (0/1) in patients with time window from onset to thrombolysis (ONT) <3.0 h, 3.0-4.5 h, 4.6-6.0 h, and >6.0 h, respectively. In the non-recanalization group, six patients were also showed with ischemic core reversibility, including 4 (4/12) in the ONT<3.0 h group and 2 (2/12) in the ONT 3.0-4.5 h group. It was found that the reversible volume was positively correlated with baseline ischemic core volume (r=0.805, P<0.001) by Spearman correlation analysis. Finally, binary Logistic regression analysis revealed that the history of hypertension, ONT and recanalization were independent predictors of reversible changes of baseline ischemic core.@*Conclusions@#The ischemic core defined by CT perfusion imaging (rCBF<30%) was considerably inaccurate for patients with ONT<6.0 h. If recanalization could be achieved within this time window, most of the patients would manifest with ischemic core reversibility, the predictors of which also included hypertension history and ONT.