DO THE BMI AND SURGEON INFLUENCE THE PATIENT DOSE IN FLUOROSCOPICALLY GUIDED LUMBAR DISCECTOMY AND FUSION?☆.

Abstract

A survey was conducted to evaluate the role of the surgeon and the patients' body size, on patient radiation dose in fluoroscopically guided lumbar discectomy and fusion (LDF) procedures. Fluoroscopy time (FT), kerma area product (KAP), cumulative dose (CD), as well as anatomical and technical data were recorded for 100 patients, who underwent single or multi-level posterior LDF, which was carried out by three senior neurosurgeons utilising a C-arm fluoroscopy system. The patients were divided into three groups based on the body mass index (BMI) values (normal, overweight, obese) and the neurosurgeon that performed each procedure (surgeon 1, surgeon 2, surgeon 3). Entrance surface dose (ESD) was estimated based on KAP values and exposure data, while the effective dose (ED) was estimated utilising the KAP values and appropriate conversion coefficients. The mean FT, KAP, CD, ESD and ED values were 11.7 s, 0.65 Gy cm2, 2.96 mGy, 11.7 mGy and 0.08 mSv for normal patients, 22.1 s, 0.94 Gy cm2, 4.27 mGy, 21.4 mGy and 0.11 mSv for overweight patients and 67.7 s, 3.59 Gy cm2, 17.79 mGy, 107.2 mGy and 0.44 mSv for obese patients. The corresponding values were 21.5 s, 0.77 Gy cm2, 3.51 mGy, 17.5 mGy, 0.09 mSv for the first, 23.0 s, 1.44 Gy cm2, 6.52 mGy, 30.2 mGy, 0.18 mSv for the second and 14.2 s, 0.64 Gy cm2, 2.91 mGy, 17.0 mGy, 0.08 mSv for the third surgeon. Overweight patients received 83% and 38% higher ESD and ED, while obese patients 816% and 450%, compared to normal patients, respectively. The CD values should be implemented with caution, as a skin dose indicator, for all patient sizes. The weight-FT product could be useful in estimating KAP during LDF procedures. The third surgeon achieved the lowest dose values. Although the first surgeon had the same FT with the second surgeon, the corresponding dose values were decreased by 50%. The differences in FT, KAP, CD and ED values among the groups of patients studied were not statistically significant (Kruskal-Wallis test, p > 0.05), although the p-values were close to the threshold of statistical significance. The pairwise comparisons showed statistically significant differences for KAP, CD and ED values between obese and normal patients and between surgeon 1 and surgeon 3 (Mann-Whitney test, p < 0.05). The ESD values showed statistically significant differences among the BMI-based groups and among the surgeon-based groups studied (Kruskal-Wallis test, p < 0.05). This fact can be attributed to the better implementation of the fluoroscopy system technical parameters concerning the patients' size, clinical conditions and complexity of the procedures. Training and awareness of neurosurgeons on radiation protection issues are of critical importance; however, further studies should be performed towards optimisation procedures regarding patient dose.