Following the implementation of the Ionising Radiations (Medical Exposure) Regulations Act 2000 and recommendation from International Commission on Radiological Protection (ICRP), the establishment of diagnostic reference levels (DRLs) for all radiological examinations became mandatory. There are no recommended or published standards or national dosage guidelines in the UK of diagnostic reference levels available for fluoroscopy-guided diagnostic and therapeutic spinal procedures. The aim of this study is to establish reference dose area product (DAP) levels for the diagnostic spinal procedures requiring fluoroscopy as a basis for setting DRLs.

All patient data consisted of diagnostic spinal procedures done in 2009 at Newcastle General Hospital under care of 4 spinal surgeons. Radiation data were collected on specific type of the procedure, DAP and screening time. Nerve root blocks, facet joint blocks and facet joint rhizolysis were included for data collection and analysis for this study. The third-quartile values were used to establish the DRLs.

There were 387 nerve root blocks with a mean exposure per injection 171.3 cGycm² (range, 3.0 to 2029.1; third quartile 209.4). Facet joint injections were 669 at a mean radiation dose 41.3 cGycm² (range, 1.9 to 541.0; third quartile 48.9). In a total 430 facet joint rhizolysis, the mean exposure was 44.4 cGycm² (range, 7.7 to 154.5; third quartile 58.4). The mean screening times were 36.7s (range, 0.4-281s; third quartile 41s) for nerve root blocks, mean 11.2s (range, 1.8-37s, third quartile 13.3s) for single facet joint block and mean 14.6s (range, 0.1-162s, third quartile 15.1s) for single facet rhizolysis.

We found the third-quartile values for setting DRLs for single level nerve root block, single facet joint block and single facet joint rhizolysis to be 209.4, 48.9 and 58.4 cGycm² respectively. We recommend that all spinal units in the UK should establish their own local DRLs to help in establishing national dosage guidelines for fluoroscopy-guided diagnostic and also therapeutic spinal procedures.