Is a further reduction of radiation exposure in scoliosis monitoring achievable using flat detector and pulsed fluoroscopy technology? - A feasibility study on human specimen

Abstract

Background: In the case of scoliosis therapy, frequent radiological monitoring of the spine is necessary. However, x-ray requires high radiation doses; therefore digital pulsed fluoroscopy with flat detector technique can be used alternatively. The latest developments in this technology lead to further dose reduction with an improved image quality. To evaluate the new system, we asked if there is a difference in dose area product (DAP) concerning the opening area (OA) and image quality settings (IQS). Further we wanted to investigate the inter-observer reliability using an established scoring system and correlate the DAP with the point value. Methods Therefore, we examined 4 cadaver spines (T1 to sacrum) with the flat detector technique using digital pulsed fluoroscopy and simulated the abdominal soft tissues with water bags. The images were merged calculating whole spine images from several digital single images and evaluated by 3 different investigators (spine surgeon, experienced pediatric radiologist, assistant physician) using an established scoring system. For comparison and validation of our model, we used digital radiography images of the cadaver spines. Results The values for the DAP increased from the small OA (33%; 0.56 µGy·m²) to the maximum OA (100%; 0.82 µGy·m²) by 45% (p = .003) and from low IQS (0.57 µGy·m²) to high IQS (0.84 µGy·m²) by 48% (p = .028). The inter-observer reliability was strong (3 vs. 1: ρ = .818; 3 vs. 2: ρ = .742; 2 vs. 1: ρ = .586; p <.001), but there was no correlation between DAP and point value (ρ = -.053, p = .588). Despite the low DAP, the setting 33% OA achieved the best point values, therefore this setting is preferred. Conclusions Using a digital fluoroscopy system allows a significant reduction of radiation exposure for whole spine images by a factor of 7.5 (3.88 µGy·m² to 0.5 µGy·m²) compared to slot-scanning x-ray (EOS).