Slagowski Jordan M, Colbert Lauren E, Cazacu Irina M, Singh Ben S, Martin Rachael, Koay Eugene J, Taniguchi Cullen M, Koong Albert C, Bhutani Manoop S, Herman Joseph M, Beddar Sam
Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Pract Radiat Oncol. 2020 Nov-Dec;10(6):434-442. doi: 10.1016/j.prro.2020.01.007. Epub 2020 Jan 24.
The purpose of this study was to quantitatively evaluate the visibility and artifacts of commercially available fiducial markers to optimize their selection for image guided stereotactic body radiation therapy.
From 6 different vendors, we selected 11 fiducials commonly used in image guided radiation therapy. The fiducials varied in material composition (e.g., gold, platinum, carbon), shape (e.g., cylindrical, notched/linear, coiled, ball-like, step), and size measured in terms of diameter (0.28-1.0 mm) and length (3.0-20.0 mm). Each fiducial was centered in 4-mm bolus within a 13-cm-thick water-equivalent phantom. Fiducials were imaged with the use of a simulation computed tomography (CT) scanner, a CT-on-rails system, and an onboard cone beam CT system. Acquisition parameters were set according to clinical protocols. Visibility was assessed in terms of contrast (Δ Hounsfield unit [HU]) and the Michelson visibility metric. Artifacts were quantified in terms of relative standard deviation and relative streak artifacts level (rSAL). Twelve radiation oncologists ranked each fiducial in terms of clinical usefulness.
Contrast and artifacts increased with fiducial size. For CT imaging, maximum contrast (2722 HU) and artifacts (rSAL = 2.69) occurred for the largest-diameter (0.75 mm) platinum fiducial. Minimum contrast (551 HU) and reduced artifacts (rSAL = 0.65) were observed for the smallest-diameter (0.28 mm) gold fiducial. Carbon produced the least severe artifacts (rSAL = 0.29). The survey indicated that physicians preferred gold fiducials with a 0.35- to 0.43-mm diameter, 5- to 10-mm length, and coiled or cylindrical shape that balanced contrast and artifacts.
We evaluated 11 different fiducials in terms of visibility and artifacts. The results of this study may assist radiation oncologists who seek to maximize contrast, minimize artifacts, or balance contrast versus artifacts by fiducial selection.
本研究的目的是定量评估市售基准标记物的可视性和伪影，以优化其在图像引导立体定向体部放射治疗中的选择。
我们从6个不同供应商处选取了11种在图像引导放射治疗中常用的基准标记物。这些基准标记物在材料成分（如金、铂、碳）、形状（如圆柱形、带缺口/线性、螺旋形、球状、阶梯形）以及以直径（0.28 - 1.0毫米）和长度（3.0 - 20.0毫米）衡量的尺寸方面存在差异。每个基准标记物位于一个13厘米厚的水等效模体中4毫米厚的 bolus中心。使用模拟计算机断层扫描（CT）扫描仪、CT在线系统和机载锥形束CT系统对基准标记物进行成像。采集参数根据临床方案设置。根据对比度（Δ亨氏单位[HU]）和迈克尔逊可视性指标评估可视性。根据相对标准偏差和相对条纹伪影水平（rSAL）对伪影进行量化。12名放射肿瘤学家根据临床实用性对每个基准标记物进行排名。
对比度和伪影随基准标记物尺寸的增加而增加。对于CT成像，最大直径（0.75毫米）的铂基准标记物出现最大对比度（2722 HU）和伪影（rSAL = 2.69）。最小直径（0.28毫米）的金基准标记物观察到最小对比度（551 HU）和减少的伪影（rSAL = 0.65）。碳产生的伪影最不严重（rSAL = 0.29）。调查表明，医生更喜欢直径为0.35至0.43毫米、长度为5至10毫米、呈螺旋形或圆柱形的金基准标记物，其在对比度和伪影之间取得了平衡。
我们从可视性和伪影方面评估了11种不同的基准标记物。本研究结果可能有助于寻求通过基准标记物选择最大化对比度、最小化伪影或平衡对比度与伪影的放射肿瘤学家。
