Substantiation of a new approach to the criteria for assessing the radiation dose of patients during Computed Tomography

PURPOSE 
To analyze the dependence of effective doses (ED) in computed tomography (CT) of different body parts on patients weight and to calculate the standard ED for the standard patient weighing 70 kg and 80 kg. 
METHODS 
CT acquisition protocols in 209 patients were single-phase (SP), in 114 multi-phase (MP). ED was calculated according to the normalized coefficients for each body area (head, chest, abdominal and pelvic organs). The values of standard ED were calculated by data approximation using linear function of ED relatively body weight for each type CT scanner and body area scanned. 
RESULTS 
During CT examination, ED increases in proportion to the body weight of patients. With SP and MP CT, the mean ED, median ED and DRLs (mSv) in all groups were slightly higher than the standard ED if the criterion was a mass of 70 kg; these indicators were close to the standard ED if the criterion was a mass of 80 kg. These features provide a basis for improving guidelines for comparing and standardizing radiation doses in CT patients by the studied areas of the body. 
CONCLUSIONS 
The study describes a method for assessing and comparing the dose of CT radiation on the example of two hospitals and two CT scanners, taking into account the weight of a standard patient. The results show that the calculation and analysis of the standard ED for each area of the body, instead of the average ED, median ED or 75 quartile ED, helps to more correctly compare radiation exposure in different medical institutions and analyze the reasons for exceeding regional or national reference diagnostic levels. In the context of a sharp increase in the number of CT studies in recent years, not exceeding the CT RDA calculated according to the standard ED criterion is designed to reduce the long-term consequences in the form of oncological pathology among the population.