Evaluation of organ dose using size-specific dose estimation (SSDE) and related cancer risk of chest CT scan during the COVID-19 pandemic (preprint)

ABSTRACT

This study aimed to estimate the individual patient’s lung and breast dose using the SSDE method as well as the effective dose in patients who underwent chest CT scans during the COVID-19 pandemic. The cancer risk incidence was estimated using excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) models of biological effects of ionizing radiation report VII (BEIR-VII). The information of about 570 patients who underwent CT scans for COVID-19 screening was used for this study. Using the header of the CT images in a python script, SSDE and effective dose were calculated for each patient. The SSDE obtained by water equivalent effective diameter (wSSDE) was considered as lung and breast dose, and applied in organ-specific cancer risk estimation. The mean value of wSSDE for females (13.26 mGy) was a bit higher than the wSSDE value for males (13.08 mGy) but it was not statistically significant (P-value = 0.41). There was no significant difference in the calculated EAR, and ERR for lung cancer between males and females at the attained age of 5, and 30 years after exposure (P-value = 0.47, 0.46 respectively). There was no significant difference between lung cancer LAR values for females and males (0.48). The results also showed a decrease in the LAR values for both lung and breast cancers by increasing the exposure age. By considering the ALARA (as low as reasonably achievable) principle, the medical staff and the public should take the benefits of CT imaging in the detection of such infections. Besides, imaging medical physicists and CT scan experts have to optimize the imaging protocols and balance the image quality for detecting abnormalities versus the radiation dose based on the ALARA principle.