Use of lead shields for radiation protection of superficial organs in patients undergoing head CT examinations

Abstract

Head computed tomography examinations are often accompanied with unnecessary irradiation of superficial organs that are rarely the main target for the investigation. The aim of this work is to demonstrate that lead shields could be effectively used to protect superficial organs without compromising image quality where superficial organ itself is not a target and that the irradiation of the superficial organ is unavoidable. The objective was achieved by first assessing the image quality using phantom measurements made with and without lead shielding in order to determine optimal shielding thickness for patient applications. The entrance surface doses (ESDs) to superficial organs of sixty patients were measured using LiF-thermoluminescent dosemeters without, with one layer, or with two layers of lead shields. Phantom studies demonstrated that the use of modified lead shields of up to 0.25 mm thickness could be used without significant effect on the image quality for central and posterior regions. In these studies, lead shields of 0.25 mm thickness reduce the ESDs to the lens of the eyes and thyroid by 44 and 51%, respectively. The image quality reduction by eye shields was significant to the anterior (i.e. orbital) region but marginal to the central and posterior regions (cerebrum). In view of the above, the use of modified lead shields could reduce the dose to the superficial organs considerably without significantly compromising image quality.

Prevalence of Protective Shielding Utilization for Radiation Dose Reduction in Adult Patients Undergoing Body Scanning Using Computed Tomography

“…31 Other studies have similarly corroborated significant dose reduction due to shielding techniques. 9,11 Despite these striking numbers, radiation shielding has been a topic of debate in the literature. 32 Some studies have indicated an increase in image noise in the area directly underlying the protective shield 31,33,34 ; in contrast, other studies indicate no significant effect on diagnostic image quality.…”

“…[5][6][7][8] Within the past decade, several studies have shown the effectiveness of shielding in decreasing radiation dose exposure to the thyroid, [9][10][11][12] breasts, 11,13 eyes, 7,9,10,14 and testes. Accordingly, our objective was to evaluate the prevalence of protective shield utilization in adult patients undergoing routine abdominopelvic, chest, or head CT scans in a randomly selected group of U.S. hospitals.…”

The Current Use and Effectiveness of Bismuth Shielding in Computed Tomography: A Systematic Review

“…7 However, its use was replaced by bismuth shielding, which provided improved opportunities to reduce dose to superficial organs within the field of view. 8 While various studies have proven that lead and bismuth provide equivalent dose reductions [9][10][11] ; bismuth shields are designed for specific superficial organs and have the added benefit of being lightweight and easy to manoeuvre. 8 Recently, the use of bismuth shields has sparked debate in relation to issues caused during scans.…”

Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations

“…demonstrated that lead shields of 0.25 mm thickness affect the protection of the superficial organs for head CT examination. The entrance surface doses (ESDs) of the eye lens and thyroid reduced 44 and 51%, respectively (11) . U. Lechel proved that an automatic exposure control systems decreased the dose by between 27% and 40% (14) .…”