Eye lens dose for medical staff assisting patients during computed tomography: comparison of several types of radioprotective glasses

Abstract

Medical staff sometimes assists patients in the examination room during computed tomography (CT) scans for several purposes. This study aimed to investigate the dose reduction effects of four radioprotective glasses with different lead equivalents and shield shapes. A medical staff phantom was positioned assuming body movement restraint of the patient during chest CT, and air kerma at the eye surfaces of the medical staff phantom and inside the lens of the four types of radioprotective glasses were measured by changing the distance of the staff phantom from the gantry, eye height, and width of the nose pad. The air kerma at the right eye surface with glasses of 0.50–0.75 mmPb and 0.07 mmPb was approximately 83.5% and 58.0%, respectively, lower than that without radioprotective glasses. The air kerma at eye surfaces decreased with all types of glasses by 67.4%–78.2% by increasing the distance from the CT gantry to the staff phantom from 25 cm to 65 cm. The air kerma at the left eye surface was larger except for the glasses with the highest lead equivalent (0.75 mmPb at the front) when the height of the eye lens for the medical staff phantom was higher. The air kerma on the left eye surface decreased by 46.9% with the widest nose pad width compared to the smallest nose pad width for the glasses with adjustable nose pad width. The radioprotective glasses for staff assisting patients during CT examinations should have a large lead equivalent and no gap around the nose and under the front lens.

Relationship between assistant’s lens exposure and dose information during computed tomography examinations

“…Conversely, Endo et al reported that 0.75 mmPb protective glasses are heavy and cause discomfort to the surgeon, although the glasses demonstrated an excellent shielding effect [24]. The use of protective glasses with a higher lead equivalent is recommended in CT examinations because of the short wearing time [25]. Additionally, the use of CT-specific protective plates and protective curtains may further reduce exposure to the lenses of assistants [26,27].…”