Influence of safety glasses, body height and magnification on the occupational eye lens dose during pelvic vascular interventions: a phantom study

Abstract

Objective By simulating a fluoroscopic-guided vascular intervention, two differently designed radiation safety glasses were compared. The impacts of changing viewing directions and body heights on the eye lens dose were evaluated. Additionally, the effect of variable magnification levels on the arising scattered radiation was determined. Methods A phantom head, replacing the operator’s head, was positioned at different heights and rotated in steps of 20° in the horizontal plane. Thermoluminescent dosimeters (TLD), placed in the left orbit of the phantom, detected eye lens doses under protected and completely exposed conditions. In a second step, radiation dose values with increasing magnification levels were detected by RaySafe i3 dosimeters. Results Changing eye levels and head rotations resulted in a wide range of dose reduction factors (DRF) from 1.1 to 8.5. Increasing the vertical distance between the scattering body and the protective eyewear, DRFs markedly decreased for both glasses. Significant differences between protection glasses were observed. Increasing magnification with consecutively decreasing FOV size variably reduced the dose exposure to the eye lens between 47 and 83%, respectively. Conclusion The safety glasses in the study effectively reduced the dose exposure to the eye lens. However, the extent of the protective effect was significant depending on eye levels and head rotations. This may lead to a false sense of safety for the medical staff. In addition, the application of magnification reduced the quantity of scattering dose significantly. To ensure safe working in the Cath-lab, additional use of protective equipment and the differences in design of protective eyewear should be considered. Key Points • Eye lens dose changes with physical size of the interventionist and viewing direction. • The use of magnification during fluoroscopic-guided interventions reduces scattered radiation.

Radiation Protection of the Eye Lens in Fluoroscopy-guided Interventional Procedures

“…If the head position is quite low, as in a seated operator, the distance between the irradiated area and the head of the operator is close, and so the lens dose will be remarkably high. However, if the operator puts on a protective eyewear, the situation can be altered and even reversed [33] . The taller the height of the operator, the lower the incidence angle of the scatter radiation.…”

“…Lead glasses can significantly reduce the radiation dose when protecting against X-rays from the front in the same horizontal plane as the eyes, with a DRF of more than five for glasses with the lead equivalent thickness of more than 0.5 mmPb and a DRF of around 2.5 for glasses with around 0.1 mmPb [29,30]. However, the effectiveness of dose reduction by protective eyewear is highly dependent on the head's position and angle [31][32][33]. DRFs of the eyewear for X-rays incident on the front are highly correlated with the lead equivalent thickness, but the correlation worsens as the incident angle increases because the influence of the eyewear design becomes larger [30,34].…”