ABSTRACT
Objective:To explore the influence of different size related parameters of common CT scanned body parts on body-specific dose estimate (SSDE) , in order to establish rapid conversion factors for SSDE.Methods:A total of 189 clinical cases were collected from 6 common CT scanned body parts, including head, nasal bone, sinus, neck, chest, abdomen and pelvis, at Beijing Tongren Hospital, Capital Medical University from March 8 to May 10, 2021. Batch-processing of image was carried out by using Matlabcode. The axial images′area, anteroposterior (AP) dimension, lateral (LAT) dimension and average CT values were calculated. The conversion factors for estimating body-specific dose values were obtained from the real effective diameter ( De) and water equivalent diameter ( Dw) of the clinical cases, and the differences in values were compared between SSDE ED and SSDE WED. Based on the information on AP, LAT, AP + LAT, estimated De, the real De and Dw obtained in clinical practices, the SSDE rapid correction factors for adult body parts were established. The convenient conversion relation between Dw and De was obtained. Based on the correction factors for Dw, the relative errors of the correction factors for various sizes related parameters were compared. Results:The SSDE fast conversion factors for the real De of the 6 body parts were 1.01, 1.01, 1.01, 0.97, 1.28, 1.32, and those for Dw were 0.87, 0.97, 0.98, 0.99, 1.42, 1.36, respectively. The relative errors of different conversion factors ranged from 0.68% to 18.05%. The conversion factors for abdomen and pelvis had the smallest difference, and those for AP and LAT of the chest had the smallest error. The differences between CTDI vol, SSDE ED and SSDE WED in sinus, chest and abdomen were statistically significant ( tsinus=2.44, 4.23, tchest=17.67, 17.00, tabdomen and pelvis =17.93, 18.75, P<0.05) . The differences between CTDI vol and SSDE WED in head, nasal bone, were statistically significant ( t=-22.27, 2.80, P<0.05) , but not with SSDE ED ( P>0.05) . The difference between CTDI vol and SSDE ED in neck was statistically significant ( t=-3.06, P<0.05) but without statistical insignificance in camparison with SSDE WED ( P>0.05) . Conclusions:SSDE WED can be used to accurately evaluate the body-specific dose estimatates, and different size related parameters can be selected for correction in different scanned body parts. The rapid conversion factor can be easily used in clinical practice to improve the accuracy of estimated radiation dose.
ABSTRACT
Objective To investigate the clinical characteristics of severe patients with influenza A H1N1. Methods Fifteen prenant pneumonia patients with influenza A H1N1 were selected from November 26 to December 20,2009. Results The average age of all patients was 24 years old,with an average gestational age of 32 weeks. Leukopenia was observed in 13. 3% of IS patients,and lymphopenia in 86. 7%. Data on the ratio of CD4 cells to CD8 cells were available for 12 patients,54. 5% of whom had an abnormal CD4:CD8 ratio(< 1. 4). Ten of the 14 patients(71. 4%)had increased serum lactate dehydrogenase levels,which were above 245 U per liter. Four patients (26. 6%) had elevated creatine kinase levels at admission. 4 cases of 15 patients (26. 7%) had decreased serum potassium levels,which were below 3.5 mmol per liter. Four patients (33. 3%)had C4 levels higer than 36 g per liter,and 4 cases had C3 less than 0.75 g per liter. All 15 patients had radiologically confirmed pneumonia with bilateral patchy alveolar opacities, affecting three or four lung quadrants. Findings on chest radiographs were consistent with the acute respiratory distress syndrome in all patients requiring mechanical ventilation. 4 cases were found a small amount of pleural effusion, of which 1 case was combined a small amount of pericardial effusion. Respiratory distress requiring intubation and mechanical ventilation developed in 9 patients within the first 24 hours after admission, who were all pregnant women. Two of them in the third trimester died, and 7 cases who were timely terminated pregnancy were in stable condition. Conclusions Pandemic influenza A(HIM) may pose an increased risk of severe illness in pregnant women, and it is easy to develop rapidly into adult respiratory distress syndrome. The pregnancy immunological tolerance may be involved in the severe lung injury process of H1N1 influenza pneumonia.