Institutional (local) diagnostic reference levels in fluoroscopically guided spine surgery.

In this study, institutional (local) diagnostic reference levels (LDRLs) and action levels (ALs) for spine interventional procedures are reported. Fluoroscopy time (FT), kerma area product (KAP), cumulative dose (CD), as well as anatomical, clinical and technical factors affecting procedure complexity were recorded for 156 patients who underwent cervical and thoraco-lumbar interventions. Patient entrance surface dose (ESD), effective dose (ED), thyroid absorbed dose and gonadal dose were also estimated, based on KAP measurements. The LDRLs and ALs were calculated as the 75th and 10th percentile of FT, KAP and CD values for the total group of patients, as well as utilizing the weight banding method and the size correction method. For the total distribution of patients, the LDRLs for cervical and thoraco-lumbar interventions are 0.15min and 0.29min for FT values, 0.10Gycm and 0.71Gycm for KAP values, as well as 0.47mGy and 3.24mGy for CD values, respectively. The corresponding ALs are 0.03min and 0.03min, 0.01Gycm and 0.07Gycm, as well as 0.05mGy and 0.33mGy for FT, KAP and CD values, respectively. The age and treated levels had a significant influence on the reference dose values only for cervical interventions, whereas none of the other included factors showed statistically significant association for both cervical and thoraco-lumbar interventions. The weight banding method resulted to reference values comparable to those obtained for the whole group of patients, while the size correction method resulted to lower values. The mean ESD values were 1.58mGy (range 0.02-13.58mGy) for cervical and 23mGy (range 0.004-390.3mGy) for thoraco-lumbar interventions. The corresponding mean ED values were 0.012mSv (range 0.001-0.097mSv) and 0.124mSv (range 0.00002-2.11mSv), respectively. The mean thyroid and gonadal doses were 0.14mGy (range 0.002-1.12mGy) and 0.044mGy (range 0.000003-1.56mGy), respectively. The LDRLs and ALs reported could contribute in the effort for establishing national DRLs and for increasing neurosurgeons awareness regarding patient dose and radiation protection issues during spine interventional procedures.