Low-dose CT of the paranasal sinuses with eye lens protection: effect on image quality and radiation dose

Abstract

The purpose of the study was to assess the effect of lens protection on image quality and radiation dose to the eye lenses in CT of the paranasal sinuses. In 127 patients referred to rule out sinusitis, an axial spiral CT with a lens protection placed on the patients eyes was obtained (1.5/2/1, 50 mAs, 120 kV). Coronal views were reconstructed at 5-mm interval. To quantify a subjective impression of image quality, three regions of interest within the eyeball were plotted along a line perpendicular to the protection at 2, 5, and 9 mm beneath skin level on the axial images. Additionally, dose reduction of a bismuth-containing latex shield was measured using a film-dosimetry technique. The average eyeball density was 17.97 HU (SD 3.7 HU). The relative increase in CT density was 180.6 (17.7), 103.3 (11.7), and 53.6 HU (9.2), respectively. There was no diagnostic information loss on axial and coronal views observed. Artifacts were practically invisible on images viewed in a bone window/level setting. The use of the shield reduced skin radiation from 7.5 to 4.5 mGy. The utilization of a radioprotection to the eye lenses in paranasal CT is a suitable and effective means of reducing skin radiation by 40%.

Delineation of temporal bone anatomy: feasibility of low-dose 64-row CT in regard to image quality

“…Therefore, some previous CT studies have suggested that the tube current may be reduced strongly without marked effect on image quality [14][15][16][17][18][19][20][21]. In high-contrast structures such as the skeletal structures of the cranium [9,21] and in particular of the sinuses [14][15][16][17][18][19][20][21], several authors have proposed the use of low-dose protocols. It was suggested that the tube current may be reduced even to 30 mAs at 120 kV for imaging the paranasal sinuses, resulting in a dose reduction of 70% in comparison to standard CT protocols [22].…”

Dose Exposure of Patients Undergoing Comprehensive Stroke Imaging by Multidetector-Row CT: Comparison of 320-Detector Row and 64-Detector Row CT Scanners

“…The dose-reducing effect of the lens protection shield is clearly evident for CTA and the combo protocol and comparable with that in the literature. [20][21][22][23] With standard settings without gantry angulation, the eye lenses are within the scanning area. We used no lens protection for the incremental scans.…”

Comparison of Eye Lens Dose on Neuroimaging Protocols between 16- and 64-Section Multidetector CT: Achieving the Lowest Possible Dose

“…Use of a bismuth-containing latex shield for lens protection in CT paranasal sinus studies has been shown to reduce the surface radiation dose by 40%, 18 without the loss of diagnostic information, though its impact on temporal bone studies is unknown. Because the orbits are rarely of concern during the interpretation of a temporal bone study and lie a far distance anterior to the middle and inner ear structures, any beam-hardening artifact related to lens protection should theoretically not affect image quality in the region of interest.…”