An effective, reliable and practical staging is of great help to the diagnosis and treatment of malignant tumors. Cervical cancer is a malignant tumor using clinical stage in gynecological tumors, but staging lacks objectivity in judging the tumor size, para-uterine invasion, vaginal margin, vascular invasion and so on. By October 2018, the International Federation of Obstetrics and Gynecology (FIGO) had revised the 2009 FIGO cervical cancer staging that had been used before.However, the changed points of the 2018 FIGO cervical cancer staging are controversial.

Objective To study the estimation method of medical exposure frequency in China through the survey of diagnostic radiology and radiotherapy institutions in selected provinces.Methods A survey of medical exposure frequency was carried out involving 557 diagnostic radiology and radiotherapy institutions in 25 provinces.The correlation analysis and multiple linear regression analysis were conducted,with the fitting effects of the models with different variables being compared.Results The total medical exposure frequencies highly correlated with number of outpatient,number of equipment and number of radiation workers (| r| ＞0.5).Representative samples of the daily medical exposure workload were obtained by stratified random sampling from the survey data.Mathematical models were built using the multiple linear regression between total medical exposure frequency and hospital levels,number of outpatients,number of inpatients,number of equipment,and number of radiation workers.The total medical exposure frequency in 2016 was estimated to be 589 million examinations based on the models.In addition,the frequencies of medical procedures were derived using the robust regression and the median regression.Conclusions There are several methods for estimating the total medical exposure frequency.It is desirable to use the stratified random sampling combined with the published statistical and monitoring data.The representativeness of sample is critical.The specification and optimization of models also require further study.

The article briefly described the frequency of CT scans and the development trend of CT exposure doses in children, and introduced the main method and achievements in the cancer risk evaluation of pediatric CT scans in different time periods. This review will provide the references for optimizing the radiation dose of CT scans.