A closer look at utilized radiation doses during chest CT for COVID-19 patients

Abstract

This study examined radiation exposure from CT scans performed on 500 adult COVID-19 patients at two major university hospitals in Morocco. A robust correlation (r = 0.82) was found between patient size and Size-Specific Dose Estimate (SSDE), which ranged from 10.11 to 17.87 mGy. The mean CTDIvol was 6.7 mGy, contrasting markedly with the mean SSDE of 12.81 mGy. This highlights a substantial difference, with the SSDE-to-CTDIvol ratio being approximately 1.91. Notably, the SSDE was nearly twice as high as the CTDIvol, underscoring the vulnerability of obese COVID-19 patients. Evaluation of different CT scanner models showed higher radiation doses associated with the Siemens Somaton Emotion 16 compared to the GE Optima CT520 Series, emphasizing the need to account for scanner-specific factors in dose optimization protocols. A comparison of chest CT reference doses (DRL) from this study with international data showed a lower mean CTDIvol here (6.7 mGy) than reported in other countries. However, the DRL in terms of DLP is in the same range or lower as compared to others. Using the BEIR VII model, the lifetime attributable risk (LAR) of cancer from COVID-19 chest CTs was estimated. Elevated risks of lung cancer in both genders and increased breast cancer risk in females were projected, albeit with limitations regarding overestimated cancer incidence. The high effective dose values, approaching 15.3 mSv, underscore the need for dose optimization, especially in obese COVID-19 patients receiving chest CTs.