Department of Radiology, Wan Fang Hospital, Taipei Medical University, 111 Hsing-Long Road, Section 3, Taipei, Taiwan.
Department of Radiology, Wan Fang Hospital, Taipei Medical University, 111 Hsing-Long Road, Section 3, Taipei, Taiwan; Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Acad Radiol. 2020 Nov;27(11):1523-1530. doi: 10.1016/j.acra.2019.12.011. Epub 2020 Feb 3.
In this study, we assessed the radiation dose to the lens and the impacts of various eye shields using either a fixed or modulated tube current.
Patients undergoing head computed tomography (CT) examinations were recruited, and each was randomly assigned to one of five imaging groups, either without a CT eye shield or with one of two types of shielding and topogram-based tube current modulation (TCM). The radiation dose at the eye lens was estimated using Gafchromic films. All CT images were analyzed for quality in the orbit and brain areas. Two radiologists also qualitatively assessed image artifacts and their impacts on image quality using three-point Likert scales.
Both barium sulfate and bismuth-antimony shields significantly reduced radiation dose to the lens (by 28.60%-31.92% and 43.87%-47.00%, respectively) while significantly inducing image artifacts. The image quality of the intraocular structure, but not the intracranial structure, was significantly degraded by shielding. In addition, discriminating the periocular tissues was improved using a bismuth-antimony shield and topogram-based TCM. Compared to fixed tube current, topogram-based TCM provided better signal-to-noise and contrast-to-noise ratios in the intracranial structures when the bismuth-antimony and barium sulfate shields were applied, respectively.
Artifacts resulting from the application of eye shields during head CT examinations can be reduced by using topogram-based TCM instead of a fixed tube current. This could be an alternative approach for maintaining image quality in CT scans that do not encompass organ-based TCM.
本研究旨在评估采用固定或调制管电流时，各种眼部屏蔽物对晶状体的辐射剂量和影响。
招募行头部 CT 检查的患者，并将每位患者随机分为五组，包括无 CT 眼部屏蔽、使用两种屏蔽中的一种和基于定位片的管电流调制（TCM）。采用 Gafchromic 胶片估算晶状体的辐射剂量。对所有 CT 图像进行眼眶和脑部区域的质量分析。两位放射科医生还使用三点 Likert 量表对图像伪影及其对图像质量的影响进行定性评估。
硫酸钡和铋锑屏蔽均显著降低晶状体的辐射剂量（分别降低 28.60%-31.92%和 43.87%-47.00%），但同时显著增加图像伪影。屏蔽后，眼内结构的图像质量明显下降，而颅内结构的图像质量无明显下降。此外，使用铋锑屏蔽和基于定位片的 TCM 可改善眶周组织的辨别能力。与固定管电流相比，当使用铋锑和硫酸钡屏蔽时，基于定位片的 TCM 可分别提高颅内结构的信噪比和对比噪声比。
与固定管电流相比，在头部 CT 检查中应用基于定位片的 TCM 可减少眼部屏蔽物导致的伪影。在不涵盖基于器官 TCM 的 CT 扫描中，这可能是一种维持图像质量的替代方法。
