Effective dose reduction in spine radiographic imaging by choosing the less radiation-sensitive side of the body

Abstract

Background context: X-ray absorption is highest in the organs and tissues located closest to the radiation source. The photon flux that crosses the body decreases from the entry surface toward the image receptor. The internal organs absorb x-rays and shield each other during irradiation. Therefore, changing the x-ray projection angle relative to the patient for specific spine procedures changes the radiation dose that each organ receives. Every organ has different radiation sensitivity, so irradiation from different sides of the body changes the biological influence and radiation risk potential on the total body, that is the effective dose (ED).

Purpose: The study aimed to determine the less radiation-sensitive sides of the body during lateral and anterior-posterior (AP) or posterior anterior (PA) directions.

Study design: The study used exposure of patient phantoms and Monte Carlo simulation of the effective doses.

Patient sample: Calculations for adults and 10-year-old children were included because the pediatric population has a greater lifetime radiation risk than adults.

Outcome measures: Pediatric and adult tissue and organ doses and ED from cervical, thoracic, and lumbar x-ray spine examinations were performed from different projections.

Methods: Standard mathematical phantoms for adults and 10-year-old children, using PCXMC 2.0 software based on Monte Carlo simulations, were used to calculate pediatric and adult tissue and organ doses and ED. The study was not funded. The authors have no conflicts of interest to declare.

Results: Spine x-ray exposure from various right (RT) LAT projection angles was associated with lower ED compared with the same left (LT) LAT projections (up to 28% and 27% less for children aged 10 and adults, respectively). The PA spine projections showed up to 64% lower ED for children aged 10 and 65% for adults than AP projections. The AP projection at the thoracic spine causes an excess breast dose of 543.3% and 597.0% for children aged 10 and adults, respectively.

Conclusions: Radiation ED in spine procedures can be significantly reduced by performing x-ray exposures through the less radiation-sensitive sides of the body, which are PA in the frontal position and right lateral in the lateral position.

Keywords: Dosimetry; Effective dose; Positioning; Projection; Radiography; Spine.