Cumulative Radiation Exposure With EOS Imaging Compared With Standard Spine Radiographs

Abstract

Study design: Retrospective comparative study.

Objectives: This study sought to estimate the total radiation exposure to scoliosis patients during the entire treatment course using standard imaging techniques versus EOS posteroanterior (PA) and anteroposterior (AP) views.

Summary of background data: EOS is a slot-scanning X-ray system designed to reduce radiation exposure in orthopedic imaging. There are few independent studies comparing organ and total effective radiation dose from standard EOS PA, AP, and lateral imaging versus conventional projection radiographs for children with spinal deformity.

Methods: A total of 42 skeletally immature idiopathic scoliosis patients were treated with bracing (21) or spinal fusion (21) and were followed to skeletal maturity. The number of scoliosis radiographs (PA and lateral) for each patient was recorded. A computerized dosing model was used to calculate estimated patient and organ doses for PA and lateral scoliosis X-rays taken with EOS or computed radiography with a filter (CR) or without a filter (CRF). Assuming that each X-ray taken delivered the same radiation as the phantom calculation, the authors estimated the total effective and organ dose that each adolescent would have received using EOS, CR, or CRF. Annual background radiation is 3 mSv.

Results: Mean number of radiographs per patient was 20.9 (range, 8-43). Patients who underwent surgical treatment had a significantly greater number of X-rays than those who were braced (27.3 vs. 14.5; p < .001). Assuming all films were CR, the mean cumulative dose was estimated at 5.38 mSv. With standard EOS films, the mean cumulative estimated dose was 2.66 mSv, a decrease of 50.6%. An AP versus PA EOS radiograph resulted in an 8 times higher radiation dose to the breasts and 4 times higher dose to the thyroid.

Conclusions: The standard EOS imaging system moderately reduced the total radiation exposure to skeletally immature scoliosis patients. Over the entire treatment course, this represented 2.72 mSv mean reduction or 0.91 years of background radiation. Posteroanterior films significantly reduced breast and thyroid dose.

Keywords: EOS; Radiation exposure; Scoliosis.