DOS 2020

194 · DOS Abstracts Intervariability in radiographic parameter and general evaluation of a low dose fluoroscopic technique in patients with idiopathic scoliosis. Christian Wong, Jens Adriansen, Jytte Jeppesen, Andreas Balslev-Clausen Dept of Orthopedics, Hvidovre hospital; Dept of Radiology, Hvidovre hospital Background: Adolescent idiopathic scoliosis (AIS) is a frequent occurring spinal disorder in the adolescent female. Serial radiographs are used to monitor for progression but has a potential radiation-induced oncogenic effect. We exam- ined a low-dose fluoroscopic technique (LDT) to perform radiographs of AIS with inherent lower risk for malignancy. Purpose / Aim of Study: The aim of the present study is to compare the LFT with traditional radiographs for scoliosis (ORT), to see if LFT is adequate for clinical radiographic evaluation of AIS as well as having lower radiation dose. Materials and Methods: Image quality were evaluated using a pediatric trunk phantom for LTF and ORT. We measured primary physical characteristics for im- age quality evaluation of noise, contrast, spatial resolution, SNR and CNR. Three independent raters evaluated the images quality by observer-based methods of ICS and VGAS of 25 phantom images. Radiation doses were evaluated by DAP measurements. Two raters performed measurements of 6 radiographic param- eters once and separately for 342 LFT images of 136 patients with AIS. Findings / Results: The average noise and contrast were approximately 15- fold higher for the LFT. The SNR and CNR was similar. Evaluating the 25 images of the phantom, the overall ICS and VGAS were 3-fold higher for ORT com- pared to LFT for L3 and similar for Th6. For the clinical radiographs, the average measurement of CA was 16.4 degrees (dg) with a standard deviation of 12 dg. The absolute average difference (MAD) was 1.67 dg. The standard error of the mean of CA was 2.72 dg for the ORT and 2.69 dg for the LFT. ICC for CA (0.852) was almost perfect, but for the other radiographic parameters fair or worse. For radiation dose, the average DAP and effective dose for the LFT were 8-fold lower than for ORT. Conclusions: In conclusion, the LFT are reliable for CA measurements, thus be- ing useful for follow-up evaluation of scoliosis progression as in a clinical setting. LFT is not adequate for appreciating details and pathology of the spinal skeletal structures, thus not useful for the initial evaluation of AIS. Even though the im- age quality is lower for LFT than ORT, the merits are the marked less radiation, thus in accordance with the principles of ALARA. 173.