Low dose contrast enhancement of biodegradable low-density stents by an approach balancing radiopaque coatings and beam filtration.

IF 3.3 3区 医学 Q2 ENGINEERING, BIOMEDICAL
Samira Ravanbakhsh, Souheib Zekraoui, Theophraste Lescot, Magdalena Bazalova-Carter, Diego Mantovani, Marc-André Fortin
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引用次数: 0

Abstract

Objective: Biodegradable cardiovascular stents made of thin, low atomic number metals (e.g. Zn, Mg, Fe) are now approved for clinical use. However, poor contrast under X-ray imaging leads to longer surgical times, high patient exposure, and sometimes stent misplacement. This study aimed at enhancing the visibility of low-Z metal stents under X-ray imaging, by combining high-Z metal coatings and beam filtration.

Approach: Photon energy spectra from W-anode X-ray beams operated at 80 and 120 kVp, were generated by the SpekCalc and BEAMnrc softwares. The contrast produced by Fe stent struts (50-µm; 10 m W coatings), as well as dose and air kerma values (by BEAMnrc), were simulated. Several types of beam hardening filters (Sn: 0.1, 0.2 mm; Cu: 0.2, 0.7 mm) were also applied. Then, Fe foils (50-µm) with W coatings (2-3 µm-thick) were fabricated by magnetosputtering. These samples were X-ray visualised, for quantification of contrast between W-coated and uncoated Fe samples. Fe struts (50-µm) were also coated with W (3.8 ± 0.2 µm), and stent-like objects were X-ray visualised.

Main results: Fe samples attenuate 6.4% (120 kVp) and 10.1% (80 kVp) spectra photons, and 25% and 34.5% for W-coated Fe samples (SpekCalc). BEAMnrc calculations revealed the highest contrast improvement in a 120 kVp beam (36.4, and 38.5%) for W-coated and uncoated Fe samples with Sn (0.2 mm), and Cu + Sn (0.2 + 0.2 mm) filters. Experimentally, the highest contrasts between Fe and W-Fe foils, were obtained with 0.2 mm Sn (580  5 % increase). The dose was also strongly reduced (70 and 75%, for 80 and 120 kVp beams). Finally, for 3D Fe stents visualised at 80 kVp, the highest CNR and CNRD values were achieved with 0.1 mm Sn (18.5 x and 20.1 mGy⁻¹; compared to 15.0 x and 12.0 mGy⁻¹ in no-filter condition).

Significance: The contrast of Fe-based stents in X-ray imaging is improved by addition of a thin layer of W and beam filtration with Sn. The precision and rapidity of biodegradable stents implantation would be improved thereby, as well as the dose to patients.

通过兼顾不透射线涂层和光束过滤的方法,实现生物可降解低密度支架的低剂量造影剂增强。
目的:由薄、低原子序数金属(如锌、镁、铁)制成的可生物降解心血管支架现已获准用于临床。然而,X 射线成像下的对比度较低,导致手术时间延长、患者暴露程度高,有时还会造成支架错位。这项研究旨在通过结合高Z金属涂层和光束过滤,提高低Z金属支架在X射线成像下的可见度:方法:使用 SpekCalc 和 BEAMnrc 软件生成在 80 和 120 kVp 下运行的 W 阳极 X 射线束的光子能量谱。模拟了铁支架支柱(50 微米;10 m W 涂层)产生的对比度以及剂量和空气开玛值(通过 BEAMnrc)。此外,还应用了多种类型的光束硬化过滤器(锡:0.1、0.2 毫米;铜:0.2、0.7 毫米)。然后,用磁控溅射法制作了带有 W 涂层(2-3 微米厚)的铁箔(50 微米)。对这些样品进行 X 射线观察,以量化 W 涂层和未涂层铁样品之间的对比度。此外,还在铁支柱(50 微米)上涂覆了 W(3.8 ± 0.2 微米),并对支架状物体进行了 X 射线观察:主要结果:Fe 样品衰减了 6.4% (120 kVp) 和 10.1% (80 kVp) 光谱光子,W 涂层 Fe 样品衰减了 25% 和 34.5% (SpekCalc)。BEAMnrc 计算显示,在 120 kVp 光束中,使用锡(0.2 毫米)和铜+锡(0.2 + 0.2 毫米)滤光片的 W 涂层和未涂层铁样品的对比度分别提高了 36.4% 和 38.5%。在实验中,使用 0.2 毫米锡时,铁箔和钨-铁箔之间的对比度最高(580  5%)。剂量也大大降低(80 和 120 kVp 光束的剂量分别为 70% 和 75%)。最后,对于在 80 kVp 下显像的三维铁基支架,0.1 毫米锡的 CNR 和 CNRD 值最高(分别为 18.5 x 和 20.1 mGy-¹;相比之下,无过滤器条件下分别为 15.0 x 和 12.0 mGy-¹):通过添加一薄层 W 和使用 Sn 进行光束过滤,可提高铁基支架在 X 射线成像中的对比度。生物可降解支架植入手术的精确性和快速性将因此得到改善,病人所受的剂量也将减少。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Physics in medicine and biology
Physics in medicine and biology 医学-工程:生物医学
CiteScore
6.50
自引率
14.30%
发文量
409
审稿时长
2 months
期刊介绍: The development and application of theoretical, computational and experimental physics to medicine, physiology and biology. Topics covered are: therapy physics (including ionizing and non-ionizing radiation); biomedical imaging (e.g. x-ray, magnetic resonance, ultrasound, optical and nuclear imaging); image-guided interventions; image reconstruction and analysis (including kinetic modelling); artificial intelligence in biomedical physics and analysis; nanoparticles in imaging and therapy; radiobiology; radiation protection and patient dose monitoring; radiation dosimetry
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