13th Annual Global Embolization Symposium & Technologies
Purpose : To study the impact of cone-beam CT (CBCT) on radiation dose in liver directed therapy (LDT) in order to quantify and further understand the level of radiation exposure from CBCT. We aim to determine what factors confer an increased risk of radiation exposure and to analyze the relationship between radiation dose and CBCT.
Material and Methods : We analyzed a prospectively acquired database of patients who underwent percutaneous LDT, including conventional and drug-eluting bead chemoembolization, Tc-99 MAA shunt studies, Yittrium-90 embolization, and bland embolization. We collected patient demographic information and intraoperative metrics including radiation exposure data from the Siemens Artis Q System, DynaCT protocol (Siemens Healthineers, Malvern, PA). For statistical analysis, linear mixed-effects models were fit using an initial step-down with a random intercept approach to account for repeated measures within subjects, using the Bonferroni method to correct for multiple comparisons. The null hypothesis was rejected, α=0.05.
Results : 144 patients underwent 331 LDT procedures, of which 209 utilized CBCT, up to five CBCT acquisitions per procedure. The average number of CBCT per procedure was 1.2. Cumulative CBCT exposure was responsible for an average of 20% of total air kerma (AK) and 33% of total dose area product (DAP), per procedure. Results demonstrated a significantly positive association between the number of CBCT and DAP (p<0.0001). For every one unit increase in the number of CBCT acquisitions, DAP increased 63 Gycm2. There was also a positive association between the outcomes of AK and DAP with male sex (p=0.0002; p=0.0002) and BMI (p<0.0001; p<0.0001). Male subjects had AK and DAP that were 418 mGy and 67 Gycm2 greater than female counterparts. For every 1 unit increase in BMI (kg/m2), AK and DAP increased by 92 mGy and 14 Gycm2, respectively.
Conclusions : Intraoperative CBCT confers significantly increased radiation exposure to patients undergoing percutaneous LDT, with additional quantifiable radiation exposure conferred to male subjects and subjects with higher BMI. Despite this knowledge, its effect on widespread use of CBCT in LDT may be limited, largely due to the poor prognoses frequently conferred to these patients. However, it is important to extrapolate this data to procedures involving younger patients, to diseases with better prognoses, and to operators. In these instances, clinical judgement regarding radiation risks and therapeutic benefit will be necessary.