Intraoperative adjustment of radiographic standard projections of the spine: Interrater- and intrarater variance and consequences of fluoro-hunting considering time and radiation exposure. A cadaveric study

BackgroundFor the acquisition of intraoperative fluoroscopic images, standard projections have to be manually adjusted. This process resembles a trial-and-error process and is therefore time-consuming and leads to increased radiation exposure for both patient and staff. In addition, the standard projections adjusted are subject to intra- and interindividual variance. However, to date, only very limited data exist in the literature quantifying the time and radiation exposure caused by the process of manually setting standard projections as well as the intra- and interindividual variance for the manual adjustment of standard projections. Material and MethodsA.p. and lateral standard projections of the vertebral bodies of two fresh-frozen specimen were manually adjusted by two examiners with a different level of experience using a mobile C-arm. The time needed for manual adjustment as well as the number of X-ray shots acquired and the radiation dose caused during this process were documented. Intra- and interindividual variance of the central beam, the orbital rotation and angulation of the C-arm was analyzed. ResultsThe median time needed was 75.9s, with no significant difference between the examiners (p=0.13). 7.1 x-ray images were acquired in average to reach subjective satisfaction with the standard projection with significantly more x-ray shots for the lateral standard (p=0.04) and for the examiner with less experience (p<0.001). Accordingly, the dose caused was more than 50% higher than for the experienced examiner (p=0.01). Mean interindividual variance of the central beam was 7.6{degrees} while the intraindividual variance was 4.2{degrees}. ConclusionIn summary, this study investigated the interrater and intrarater variance for standard manual level setting in the thoracic and lumbar spine. Additionally, we were able to quantify the time and number of radiographs required for this procedure for different levels of experience, as well as the resulting radiation dose.