Objective : To estimate the prevalence and risk factors of suicide ideation,suicide planning and suicide attempts among middle school students and to provide reference for suicide intervention. Methods : The students of grade 7 to 12 in Ningbo were recruited through multi-stage random sampling method. A self-reported questionnaire survey was conducted to collect the information about suicide ideation,suicide planning and suicide attempts within 12 months. A multivariate logistic regression model was used to analyze the risk factors for the three aspects of suicide among middle school students. Results: A total of 10 729 questionnaires were sent out and 10 726 valid ones were collected,with a validity rate of 99.97%. The prevalence rates of suicide ideation,suicide planning and suicide attempts among middle school students during the last 12 months were 12.93%,4.54% and 5.06%,respectively. The results of multivariate logistic regression analysis indicated that females（OR：1.397-1.575,95%CI：1.178-1.927）,students of grade 7 to 9（OR：1.625-1.824,95%CI：1.323-2.082）,poor health condition（OR：1.160-2.131,95%CI：1.005-2.985）,loneliness（OR：1.574-4.423,95%CI：1.221-5.254 ）,desperation（OR：2.796-3.232,95%CI：2.400-3.990）,anxiety（OR：1.890-2.117,95%CI：1.503-2.496）,less than 8 hours a day of sleep（OR：1.152-1.263,95%CI：1.030-1.594）,smoking（OR：1.476-2.074,95%CI：1.055-3.072）,drinking（OR：1.479-1.863,95%CI：1.271-2.296）,fighting（OR：1.716-1.941,95%CI：1.330-2.422）and school bullying（OR：2.254-3.292,95%CI：1.342-5.277）were common risk factors for suicide ideation,suicide planning and suicide attempts;physical activity（OR：0.597-0.720,95%CI：0.474-0.923）was a common protective factor for suicide ideation,suicide planning and suicide attempts. Conclusion Females,lower grade,poor health condition,loneliness,desperation,anxiety,lack of sleep,smoking,drinking,fighting,school bullying and physical activity were influencing factors for suicidal behaviors.

Objective To analyze the effect of quality of life (QOL) on the prognosis of long-term survivors with nasopharyngeal carcinoma (NPC). Methods A total of 192 NPC patients treated between 1999 and 2000 and with tumor-free survival before July 2003 were enrolled in this study. All patients received QOL measurement between July and August in 2003. Measurement scales included Chinese SF-36 questionnaire and a checklist consisting of fourteen items about self-rating symptoms. The median follow-up time was 7.9S years (range 2.67-9.55 years). The effects of QOL, social demographic and clinical factors on prognosis were analyzed. Results Univariate analysis showed that QOL affected the tumor-free survival and overall survival. Multivariate analysis showed that hypomnesia was an independent prognostic factor of tumor-free survival, while trismus, headache and age were independent prognostic factors of overall survival. The younger and the better QOL had better prognosis. The other sociodemographic and clinical factors had no prognostic value. Conclusion QOL is an important factor affecting the prognosis of long-term survivors with NPC, and it should be routinely evaluated during the follow-up.

Objective To investigate the difference of size-specific dose estimates ( SSDEs ) based on effective diameter ( def ) and water equivalent diameter ( dw ) in coronary computed tomography angiography ( CCTA) and explore the causes. Methods A total of 99 patients undergoing CCTA were enrolled in this retrospective study. SSDEs ( SSDEd ef and SSDEdw ) were calculated in two approaches using def and dw , respectively. Mean absolute relative difference ( MARD) was computed as an index to quantify the consistency of SSDEd ef and SSDEdw . Multivariate stepwise regression analysis was performed to study the factors influencing MARD. Results The values def and dw were positively correlated with body mass index (BMI) (r=0. 869, 0. 823, P<0. 05). The median (interquartile range) of SSDEdef and SSDEdw were 12. 34 ( 11. 75, 12. 98) mGy, 13. 78 ( 13. 02, 15. 04) mGy, respectively. SSDEdef was lower by 10. 45％ than SSDEdw( Z=-8. 186, P<0. 05) . Both SSDEdef and SSDEdw were negatively correlated with BMI and dw(r=-0. 765, -0. 680, -0. 701, -0. 840, P<0. 05). MARD of SSDEdef and SSDEdw was generally at 11. 39％. No statistical significance was found in the correlation of MARD with BMI ( r=0. 031, P>0. 05) , however, positive correlation was shown between MARD and def ( r=0. 251, P<0. 05) , but negative correlation for MARD and dw(r=-0. 379, P<0. 05). With respect to the factors influencing MARD, four variables were included into the regression equation. MARD was positively correlated with the area of both air-filled lungs ( Arealow ) and soft tissues ( Areasoft ) (β=0. 634, 0. 102, P<0. 05) , and negatively correlated with the area of bone, enhanced cardiac chambers and aorta ( Areahigh ) and the CT value of air-filled lungs ( SIlow ) (β=-0. 234,-0. 343, P<0. 05) . Conclusions SSDEdef was approximately 10. 45％ lower than SSDEdw , which was predominantly influenced by the area of air-filled lungs due to the characteristics of low X-ray attenuation in CCTA.

Objective:To compare the difference between breast bracket combined with polyurethane foam and single polyurethane foam in the accuracy of immobilization, providing a better immobilization for breast cancer radiotherapy.Methods:Fifty breast cancer patients who received radiotherapy in Sun Yat-sen University Cancer Center from March 2021 to July 2021 were selected. Among them, 25 patients were immobilized with polyurethane foam (foam group), and the other 25 patients were immobilized with polyurethane foam combined with breast bracket (combination group). All patients were scanned by CBCT once a week to obtain setup errors in the SI, LR and AP directions for t-test. The formula M PTV=2.5 Σ+0.7 σ was used to calculate the margin of the planning target volume(M PTV). Results:The setup errors in the foam group were SI (2.0±3.26) mm, LR (0.88±2.76) mm, AP (1.22±3.55) mm, Rtn -0.24°±0.85°, Pitch 0.16°±1.11°, Roll -0.32°±1.05°, and the M PTV were 6.75 mm, 8.46 mm and 8.73 mm, respectively. The setup errors in the combination group were SI (1.0±3.01) mm, LR (0.62±2.74) mm, AP (1.82±3.21) mm, Rtn 0.64°±0.59°, Pitch 0.71°±1.22°, Roll 0.29°±0.73°, and the M PTV were 6.35 mm, 7.47 mm, and 7.61 mm, respectively. After comparing the setup errors in the three-dimensional directions between two groups, the t value of LR, SI, AP and Rtn, Pitch, Roll was -4.304, -2.681, 1.384, and -9.457, -3.683, -5.323, respectively. And the differences in the LR, SI, Rtn, Pitch and Roll directions were statistically significant (all P<0.05). Conclusions:The immobilization effect of polyurethane foam combined with breast bracket is better and the M PTV is also smaller than those of polyurethane foam alone. Therefore, it is recommended to use polyurethane foam combined with breast bracket for immobilization in breast cancer radiotherapy.