Raghu L. Motaganahalli, Angela Martin, James Slaven, Gary W. Lemmon, Alok Gupta, Alan P. Sawchuk, Andres Fajardo, George Akingba, Dolores Cikrit, Michael Murphy, Michael C. Dalsing
Surgery-Section of Vascular Surgery, Indiana University School of Medicine, Indianapolis, IN.
OBJECTIVES: Low-linear energy transfer (LET)radiation exposure (RE) from frequent CT scans increases risk of acquiring a new cancer. We used a model (BEIR VII) given by national research council for estimating life time risk of leukemia due to CT scans performed for POS-EVAR
METHODS: We estimated excess relative risk (ERR) of Leukemia due to RE from CT scans for POS-EVAR using BEIRVII committee’s preferred model: ERR (D, s, e, t) = βs D (1+θD) exp [γe*+δlog (t/25) +φ e* log (t/25)]{D is dose in sieverts (Sv), s is sex, and e* is (e-30)/10 for e<30 and 0 for e≥30 (e is age at RE in years), t(time since RE)}. As in table ERRs and relative risk reduction were calculated for various models. The risk was stratified into age groups, gender and radiation doses per CT scan (15 or 31 mSv).Paired t-test was used for analysis
RESULTS: Cumulative ERR for Leukemia from radiation was higher in those exposed to contrast CT (0.73, p<0.0001), females (0.76),young patients with highest in the 50-55 age group (ERR=1.17) and lowest in the octogenarians and older (ERR=0.36) .Table shows significant difference between the ERR/RRR of leukemia in those patients who would obtain surveillance CTs at all-time points vs. those when an alternative modalities used at some time points (p-value < 0.0001)
CONCLUSIONS: Routine CT scans for surveillance after EVAR increases risk for acquiring leukemia due to radiation exposure. The risk is higher in the young, females and with contrast CT scans. Routine CT scans should hence be limited to avoid increased risk of malignancy
AUTHOR DISCLOSURES: G. Akingba, Nothing to disclose; D. Cikrit, Nothing to disclose; M. C. Dalsing, Nothing to disclose; A. Fajardo, Nothing to disclose; A. Gupta, Nothing to disclose; G. W. Lemmon, Nothing to disclose; A. Martin, Nothing to disclose; R. L. Motaganahalli, Nothing to disclose; M. Murphy, Nothing to disclose; A. P. Sawchuk, Nothing to disclose; J. Slaven, Nothing to disclose.
Excess Relative Risk and Relative Risk Reduction(with Model1) for Leukemia due to Contrast CT scans
Age Group (In Years) |
|
50-55 |
>55-60 |
>60-65 |
>65-70 |
>70-75 |
>75-80 |
>80 |
|
Model 1 |
ERR |
1.17 |
1.04 |
0.86 |
0.68 |
0.51 |
0.35 |
0.36 |
|
Model 2 |
ERR RRR |
0.45 2.60 |
0.39 2.67 |
0.33 2.61 |
0.28 2.43 |
0.21 2.43 |
0.16 2.19 |
0.29 1.24 |
p<0.0001 |
Model 3 |
ERR RRR |
0.31 3.77 |
0.27 3.85 |
0.23 3.74 |
0.20 3.40 |
0.16 3.19 |
0.13 2.69 |
0.28 1.29 |
p<0.0001 |
Model 1: CT Scans at 0, 6, 12, 18, 24, 36, 48 months and yearly after.
Model 2: CT scans at 0, 1, 12 months and once in 3 years.
Model 3: CT scans at 0, 1, 12 months and once in 5 years.
Posted April 2012