DEVELOPMENT OF A SPECIALISED TAPE MEASURE TO ESTIMATE THE SIZE-SPECIFIC DOSE ESTIMATE

ESTIMATION OF PEDIATRIC DOSE DESCRIPTORS ADAPTED TO INDIVIDUAL SPECIFIC SIZE FROM CT EXAMINATIONS

Clinical challenges in pediatrics dose estimation by the displayed computed tomography (CT) dose indices may lead to inaccuracy, and thus size-specific dose estimate (SSDE) is introduced for better-personalized dose estimation. This study aims to estimate pediatric dose adapted to specific size. This retrospective study involved pediatric population aged 0-12 y. SSDE was derived from scanner reported volume CT dose index (CTDIvol), based on individual effective diameter (Deff) with corresponding size correction factors. The correlations of Deff with other associated factors such as age, exposure setting, CTDIvol and SSDE were also studied. The average Deff of Malaysian pediatric was smaller than reference phantom size (confidence interval, CI = 0.28, mean = 14.79) and (CI = 0.51, mean = 16.33) for head and abdomen, respectively. These have led to underestimation of pediatric dose as SSDE was higher than displayed CTDIvol. The percentage differences were statistically significant (p < .001) ranged from 0 to 17% and 37 to 60% for head and abdominal CT, respectively. In conclusion, the clinical implementation of SSDE in pediatric CT imaging is highly relevant to reduce radiation risk.

CAN THE SIZE-SPECIFIC DOSE ESTIMATE BE DERIVED FROM THE BODY MASS INDEX? A FEASIBILITY STUDY

Size-specific dose estimate ($\mathbf{SSDE}$) index appears to be more suitable than the commonly used volume computed tomography dose index ($\mathbf{C}{\mathbf{TDI}}_{\mathbf{vol}}$) to estimate the dose delivered to the patient during a computed tomography (CT) scan. We evaluated whether an ${\mathbf{SSDE}}_{\mathbf{BMI}}$ can be determined from the patient's body mass index ($\mathbf{BMI}$) with sufficient reliability in the case that a $\mathbf{SSDE}$ is not given by the CT scanner. For each of the three most used examination types, CT examinations of 50 female and 50 male patients were analyzed. The $\mathbf{SSDE}$ values automatically provided by the scanner were compared with ${\mathbf{SSDE}}_{\mathbf{BMI}}$ determined from $\mathbf{C}{\mathbf{TDI}}_{\mathbf{vol}}$ and $\mathbf{BMI}$. A good accordance of ${\mathbf{SSDE}}_{\mathbf{BMI}}$ and $\mathbf{SSDE}$ was found for the chest and abdominal regions. A low correlation was observed for the head region. The presented method is a simple and practically useful surrogate approach for the chest and abdominal regions but not for the head.

SIMPLE METHOD OF MEASURING SSDE FOR HEAD CT: FACILITATING PRE-CT SCAN DOSE CALCULATION USING SPECIALIZED HEAD SCAN BAND

In this study, scaled scan band was developed to provide size-specific dose estimation (SSDE) values based on head circumference of patients undergoing computed tomography (CT) scans. The scan band was tested in 40 consecutive head CT examinations. The accuracy of the specialized scan band method was determined by comparing SSDEband with SSDE293,forehead, SSDEmean and SSDEcenter. SSDE293,forehead was used as the control value. The results of the linear fit of SSDEband, SSDEmean and SSDEcenter against SSDE293, forehead, were R2 = 0.958, R2 = 0.984 and R2 = 0.936, respectively. There was no significant difference between SSDEband, SSDEmean and SSDEcenter for SSDE293,forehead. Use of the proposed scan band method makes it possible to accurately determine the required radiation dose before a CT examination is performed.