Objective:To evaluate the cumulative dose of the target volume and organs at risk (OARs) in intensity-modulated radiation therapy (IMRT) for large volume non-small cell lung cancer (NSCLC) based on rigid and deformation registration methods. The dosimetric changes between the initial and second treatment plans were compared.Methods:Thirty patients treated with IMRT for large volume NSCLC with twice 4DCT scans acquired before radiotherapy and after 20 fractions of radiotherapy were recruited. The initial treatment plan (Plan 1) based on the average density projection CT (CT 1-avg) of the first 4DCT images and the second treatment plan (Plan 2) based on the average density projection CT (CT 2-avg) of the second 4DCT images were calculated. Then, the dose distributions of Plan 1 and Plan 2 were accumulated based on rigid and deformation registration methods to obtain Planrig and Plandef, respectively. Finally, the volume changes of gross tumor volume (GTV) and OARs between two CT scans were compared. The dose-volume parameters between Plan 1 and other plans (including Plan 2, Planrig and Plandef) were also statistically compared. Results:Compared with the initial CT scan, the mean volume of GTV and heart on the second CT was decreased by 44.2% and 5.5%, respectively, while the mean volume of ipsilateral lung, contralateral lung and total lung was increased by 5.2%, 6.2% and 5.8%, respectively (all P<0.05). Compared with Plan 1, the D 95%, D 98% and V 100% of target volume IGTV (GTV fusion of 10 4DCT phases) and PTV in Plan 2 did not significantly change (all P>0.05), and those in Planrig and Plandef were decreased (all P<0.05). The dose-volume parameters of spinal-cord, heart, ipsilateral lung and total lung in Plan 2, Planrig and Plandef were significantly lower than those in Plan 1(all P<0.05). Among them, the V 30Gy and D mean of heart were decreased by 27.3%, 16.5%, 15.3% and 15.2%, 6.6%, 5.6%, respectively. The V 20Gy and D mean of total lung were decreased by 15.6%, 4.5%, 3.7% and 15.7%, 6.2%, 5.1%, respectively. Some dose-volume parameters (including D 95% and D 98% of target volume, V 40Gy of heart, V 20Gy and D mean of the ipsilateral lung and the total lung) of Plandef were higher than those in Planrig (all P<0.05). The Dice similarity coefficients (DSCs) of OARs after deformation registration were significantly higher than those after rigid registration ( P<0.05). Conclusions:The dose-volume parameters of OARs significantly differ between Plan 1 and Plan 2. Hence, all these parameters have a large degree of deviation in predicting radiation-induced injury of OARs. Nevertheless, the dose-volume parameters obtained by deformation registration can enhance the prediction accuracy.

Objective:Taking emergency department (ED) as a starting point, to analyze the epidemiological characteristics and mortality risk factors of sepsis, and to provide evidences for ED to carry out the strategy of "three early and two lower" for sepsis.Methods:Based on the ED and inpatient medical record management information platform of Tianjin Medical University Gernal Hospital, adult ED patients with sepsis from January 1, 2017 to December 31, 2020 were included according to the third international consensus definitions for sepsis and septic shock in 2016 and the consensus of Chinese experts on early prevention and blocking of sepsis in 2020. The epidemiological characteristics of patients were retrospectively analyzed. Chi-square test was used to compare the difference of age, sex, hospitalization times, length of stay, hospitalization cost and infection location between dead patients and survival patients, and a stepwise logistic regression model was used to analyze the influencing factors of mortality in hospitalized patients with ED sepsis.Results:A total of 7 494 patients with sepsis in ED were included in this study, and the annual and monthly component ratios varied from 3.8‰ to 6.1‰ and 2.0‰ to 9.0‰, respectively. The main characteristics of patients with sepsis in ED were as follows: 40-69 years old (46.0%), male (59.0%), mostly diagnosed with sepsis (96.8%), mainly treated with urban health insurance (59.6%), and ED diagnosis and treatment fees of 2 000-8 000 Yuan (51.1%). The mortality of hospitalized patients with ED sepsis was 24.4% and that of hospitalized patients with septic shock was 28.8%. The main characteristics of hospitalized patients with ED sepsis were as follows: most of them were male (56.2%) patients over 70 years old (56.0%), most of them were diagnosed with sepsis (94.0%) and hospitalized for the first time (76.0%), the median hospitalization time was 15 d, most of them were hospitalized under urban health insurance (65.2%), and the median hospitalization fees was 47 000 Yuan. The risk factors of death were influenced by age and length of stay. Patients aged 70 years or older had a higher risk of death than those aged from 18 to 39 years, and patients with a length of stay of more than 7 d had a lower risk of death than those with a length of stay of shorter than 7 d. The primary infection focus were mainly respiratory and urinary systems, while the death rate of patients with hematological and abdominal infections was relatively high, and the difference was statistically significant ( P<0.01). Respiratory and abdominal infections were risk factors for death in patients with ED sepsis. Conclusions:The composition ratio of sepsis in ED patients is not regular in time, so vigilance of sepsis in elderly men and patients with respiratory system, blood system, urinary system and abdominal infections should be constantly raised. Patients with sepsis who are older, hospitalized more frequently, hospitalized for a shorter time, and infected in the respiratory system or abdomen have a higher risk of death.

Objective: To study the effects of different CT values assignment methods on the dose calculation of radiotherapy plan for brain metastases, which will provide a reference for radiotherapy treatment planning based on MR images. Methods: A total of 35 patients treated with radiotherapy for brain metastases were selected, with pre-treatment CT and MR simulated positioning performed at the same day. Based on the simulation CT images, three dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) plans were calculated as the original plan (Plan1). The CT and MR images were rigidly registered and then the main tissues and organs were delineated on CT and MR images. The average CT values of each tissue and organ were calculated. Three groups of pseudo CT were generated by three CT values assignment methods based on the CT images: whole tissue was assigned 140 HU; cavity, bone and other tissues were assigned -700 HU, 700 HU and 20 HU, respectively; different tissues and organs were assigned corresponding CT values. The dose distribution of Plan1 was recalculated on three groups of pseudo-CT to obtain Plan2, Plan3 and Plan4, respectively. Finally, the dosimetric difference between Plan1 and other plans (including Plan2, Plan3 and Plan4) were compared. Results: The average CT values of bone and cavity were (735.3±68.0) HU and (-723.9±27.0) HU, respectively. The average CT values of soft tissues was mostly distributed from -70 to 70 HU. The dosimetric differences between Plan2, Plan3, Plan4, and Plan1 decreased in turn. The differences of maximum dose of lens were the biggest, which can reach more than 5.0%, 1.5%-2.0% and 1.0%-1.5%, respectively, and the differences of other dose parameters were basically less than 2.0%, 1.2% and 0.8%, respectively. In the pixelwise dosimetric comparison, the areas with more than 1% difference in the local target cases were mainly distributed in the skin near the field. On the other hand, those in the whole brain target cases were mainly distributed at the bone, cavity, bone and soft tissues junction, and the skin near the field. In addition, the dose calculation error of CT value assignment methods in 3D-CRT plan was slightly larger than that in IMRT plan, and that in whole brain target cases were significantly larger than that in local target cases. Conclusions Different CT value assignment methods have a significant effect on the dose calculation of radiotherapy for brain metastases. When appropriate CT values are given to bone, air cavity and soft tissue, respectively, the deviation of dose calculation can be basically controlled within 1.2%. And by assigning mass CT values to various tissues and organs, the deviation can be further controlled within 0.8%, which can meet the clinical requirements.

Objective: To investigate the changes of accumulated dose in target area and organs at risk (OARs) for radiotherapy of left breast cancer by deformable and rigid image registration. Methods: A total of 16 left breast cancer patients treated with 6 MV X-ray IMRT were analyzed retrospectively. All targets included the lymph node drainage area and the chest wall. All patients underwent simulation of the primary positioning and repositioning to obtain CT images. Primary and secondary treatment plans were developed using primary positioning CT (CT1) and repositioning CT (CT2), denoted as Plan1 and Plan2 respectively. The dose distribution of Plan2 was mapped to CT1 with rigid and deformable registration from CT2 to CT1 and then added to the dose distribution of Plan1 to obtain Plan-rigid and Plan-deform, respectively. The dosimetric differences between targets and the OARs of the four plans were compared. Results: The CTV volume on CT2 was reduced by 6.64% from that on CT1. The homogeneity index (HI) increased by 23.05% after deformation-based accumulation. The Dice similarity coefficients (DSCs) of the heart, left lung and right lung were lower than those before deformable registration (0.94±0.01 vs. 0.89±0.05, 0.96±0.01 vs. 0.91±0.03, and 0.96±0.01 vs. 0.92±0.03, respectively), and the differences were statistically significant (Z=-3.208, -3.533, -3.535, P<0.05). There were no significant differences in dose-volume indices of heart and left lung between Plan1 with other plans(P>0.05), while the dose-volume indices in Plan-rigid were higher than that in Plan-deform. Conclusions Rigid registration is recommended in patients undergoing radical resection of left breast cancer with little change in the volume and dose-volume index of the target area and organs at risk. The dose-volume index of the initial intensity modulation plan can basically reflect the dose-volume statistics of both lungs and heart.