Objective:In carbon ion treatment planning of water phantom, establish a conversion factor calculation system and conversion factor curves for organs at risk (OAR) for microdosimetric kinetic models (MKM) and local effect models (LEM), and validate them in clinical patient planning.Methods:Using a uniform spherical water phantom as the research object, relative biological effectiveness-weighted doses (RWD) for the LEM were re-calculated based on the physical dose of RayStation-MKM. The median dose within the planning target volume (PTV) of LEM and MKM was regarded as the conversion factor. The impacts of single-fraction target prescription dose, spread-out Bragg peak (SOBP) width and depth, shape, and irradiation mode on the conversion factor were assessed, and a conversion factor calculation system was established. Additionally, the accuracy of the conversion factor calculation system was validated using both water phantoms and clinical patient cases. The conversion factor curves for OAR were computed based on clinical patient treatment plans.Results:The primary influencing factors for the conversion factors were the single-fraction prescription dose, target SOBP width and depth. The conversion factors were increased with the increase of SOBP width and target depth, whereas decreased with the increase of the single-fraction prescription dose. Under single-field irradiation, a conversion factor calculation system was established based on above 3 parameters. For the plans of 9 patients, the average difference between the calculated results and the conversion factor calculation system was 0.340% ± 0.203%, and the average difference in the conversion curves for OAR was 2.650% ± 2.399%.Conclusion:A dose conversion factor calculation system and conversion factor curves for OAR for carbon ion radiotherapy are established for MKM and LEM, and their accuracy meets the requirements for use in clinical patient treatment plans.

Objective:To analyze the impact of stressful life events on the social activity participation of middle-aged and elderly adults in China, providing a scientific basis for improving their quality of life.Methods:This study was conducted in January 2024.Data were derived from the China health and retirement longitudinal study (CHARLS) conducted from 2011 to 2020. SPSS 25.0 software was used for statistical analysis.Ordered Logistic regression analysis was employed to explore the association between stressful life events experienced over the past decade and the level of social activity participation, with stratified analysis by age, gender, and place of residence.Results:A total of 10 838 middle-aged and elderly adults were included in this study. The proportions of individuals with no social activity participation, low social activity participation, and high social activity participation were 52.07%(5 643/10 838), 24.21%(2 624/10 838), and 23.72%(2 571/10 838), respectively. After adjusting for sociodemographic characteristics and health-related behaviors, individuals who experienced stressful life events were 15.2% less likely to participate in social activities compared to those who did not ( RR=0.848, 95% CI=0.786-0.915).Stratified analysis revealed that the decrease in the likelihood of social activity participation following stressful life events was significantly greater in urban residents than that in rural residents ( Pinteraction=0.004). Conclusion:Experiencing stressful life events over the past decade may reduce the level of social activity participation among middle-aged and elderly adults. It is recommended to strengthen psychological counseling for this population and encourage active social engagement.

Objective:To analyze the impact of stressful life events on the social activity participation of middle-aged and elderly adults in China, providing a scientific basis for improving their quality of life.Methods:This study was conducted in January 2024.Data were derived from the China health and retirement longitudinal study (CHARLS) conducted from 2011 to 2020. SPSS 25.0 software was used for statistical analysis.Ordered Logistic regression analysis was employed to explore the association between stressful life events experienced over the past decade and the level of social activity participation, with stratified analysis by age, gender, and place of residence.Results:A total of 10 838 middle-aged and elderly adults were included in this study. The proportions of individuals with no social activity participation, low social activity participation, and high social activity participation were 52.07%(5 643/10 838), 24.21%(2 624/10 838), and 23.72%(2 571/10 838), respectively. After adjusting for sociodemographic characteristics and health-related behaviors, individuals who experienced stressful life events were 15.2% less likely to participate in social activities compared to those who did not ( RR=0.848, 95% CI=0.786-0.915).Stratified analysis revealed that the decrease in the likelihood of social activity participation following stressful life events was significantly greater in urban residents than that in rural residents ( Pinteraction=0.004). Conclusion:Experiencing stressful life events over the past decade may reduce the level of social activity participation among middle-aged and elderly adults. It is recommended to strengthen psychological counseling for this population and encourage active social engagement.

Objective:In carbon ion treatment planning of water phantom, establish a conversion factor calculation system and conversion factor curves for organs at risk (OAR) for microdosimetric kinetic models (MKM) and local effect models (LEM), and validate them in clinical patient planning.Methods:Using a uniform spherical water phantom as the research object, relative biological effectiveness-weighted doses (RWD) for the LEM were re-calculated based on the physical dose of RayStation-MKM. The median dose within the planning target volume (PTV) of LEM and MKM was regarded as the conversion factor. The impacts of single-fraction target prescription dose, spread-out Bragg peak (SOBP) width and depth, shape, and irradiation mode on the conversion factor were assessed, and a conversion factor calculation system was established. Additionally, the accuracy of the conversion factor calculation system was validated using both water phantoms and clinical patient cases. The conversion factor curves for OAR were computed based on clinical patient treatment plans.Results:The primary influencing factors for the conversion factors were the single-fraction prescription dose, target SOBP width and depth. The conversion factors were increased with the increase of SOBP width and target depth, whereas decreased with the increase of the single-fraction prescription dose. Under single-field irradiation, a conversion factor calculation system was established based on above 3 parameters. For the plans of 9 patients, the average difference between the calculated results and the conversion factor calculation system was 0.340% ± 0.203%, and the average difference in the conversion curves for OAR was 2.650% ± 2.399%.Conclusion:A dose conversion factor calculation system and conversion factor curves for OAR for carbon ion radiotherapy are established for MKM and LEM, and their accuracy meets the requirements for use in clinical patient treatment plans.