A New Method for Estimating of Patient Effective Dose in Computed Tomography Based on Body Mass Index: Performance of the Method in Abdomen-Pelvic Examination

Introduction: The CT Provide high quality images, especially in low-contrast soft tissue, are another advantage. Along with all the benefits that the CT scans which have, the patient dose of this modality is much greater than other methods. As a result, medical imaging community must ensure that the benefits of radiological examination for each patient are higher than related risks. Although the CT has a small percentage of radiological examination, but it has a large contribution on the exposure to the community. the purpose of the present study was to investigate how the introduction of MDCT scanners and patient-size-dependent imaging protocols have affected patient doses and propose a simple method to predict an estimation of the organ and effective doses by using BMI and mAeff. The nobility of the present scientific study was to investigate how the introduction of MDCT scanners and patient-size-dependent imaging protocols have affected patient doses. Materials and Methods: Demographic data of each patient were recorded as well as data from a CT scan of the abdomen and pelvic of 52 patients were studied. For assessment of patient and effective doses, the information related to the scan in ImPACT software was applied. The results are analyzed and regression was used in order to examine the relation between the results of the scan data in MATLAB environment. Results: The research findings showed that the received dose to the most patients is the same as determined by the ICRP103. An average of the effective dose(6mSv) was less than predicted amount by ICRP103. To estimate the effective dose of the body, according to the patient’s BMI, an equation was obtained [Effective Dose (mSv) = 0.257 BMI - 0.637]. The results from this equation are corresponded to the calculated dose by Impact (R2>0.95). In addition, the method was proposed to predict the parameters of mAeff and DLP resulted from the related scan. [mAeff (mGy.cm) = 4.73 BMI -19.81 , DLP(mGy.cm) = 17.17 BMI -56.36]. Conclusion: According to the results of this study, authors proposed a good alternative to estimate the effective dose according to BMI instead of ImPACT calculations for scanners and scanning conditions as well as a method to predict the effective dose by using the parameters of the CT system and BMI without being radiated on the patients.