What is SSDE?
The size-specific dose estimate (SSDE) was introduced by AAPM Task Group 204 to address the difficulty in comparing CT dose indices between protocols and scanners  . The SSDE was derived using computer models designed to simulate CT scanning of patients of different age, gender, and size, because these factors strongly influence the radiation dose received. The SSDE is calculated by multiplying the CTDI vol by a conversion factor that depends on patient diameter at the center of the scan region. It helps to provide a better estimate of the CTDI vol that accounts for patient size. It is designed to be used for pediatric patients and adult patients up to a specific diameter. Using the SSDE to compare protocols across scanners or patients is more accurate than using an uncorrected CTDI vol or DLP, although the SSDE is also not a measurement of actual patient absorbed dose