Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Department of Radiology, Japanese Red Cross Ishinomaki Hospital, Ishinomaki, Japan.
J Appl Clin Med Phys. 2023 May;24(5):e13917. doi: 10.1002/acm2.13917. Epub 2023 Feb 25.
The purpose of this study was to evaluate the deformable image registration (DIR) accuracy using various CT scan parameters with deformable thorax phantom. Our developed deformable thorax phantom (Dephan, Chiyoda Technol Corp, Tokyo, Japan) was used. The phantom consists of a base phantom, an inner phantom, and a motor-derived piston. The base phantom is an acrylic cylinder phantom with a diameter of 180 mm, which simulates the chest wall. The inner phantom consists of deformable, 20 mm thick disk-shaped sponges with 48 Lucite beads and 48 nylon cross-wires which simulate the vascular and bronchial bifurcations of the lung. Peak-exhale and peak-inhale images of the deformable phantom were acquired using a CT scanner (Aquilion LB, TOSHIBA). To evaluate the impact of CT scan parameters on DIR accuracy, we used the four tube voltages (80, 100, 120, and 135 kV) and six reconstruction algorithms (FC11, FC13, FC15, FC41, FC44, and FC52). Intensity-based DIR was performed between the two images using MIM Maestro (MIM software, Cleveland, USA). Fiducial markers (beads and cross-wires) based target registration error (TRE) was used for quantitative evaluation of DIR. In case with different tube voltages, the range of average TRE were 4.44-5.69 mm (reconstruction algorithm: FC13). In case with different reconstruction algorithms, the range of average TRE were 4.26-4.59 mm (tube voltage: 120 kV). The TRE were differed by up to 3.0 mm (3.96-6.96 mm) depending on the combination of tube voltage and reconstruction algorithm. Our result indicated that CT scan parameters had moderate impact of TRE, especially for reconstruction algorithms for the deformable thorax phantom.
本研究旨在评估使用不同 CT 扫描参数和可变形胸部体模进行变形图像配准（DIR）的准确性。我们使用了自主研发的可变形胸部体模（Dephan，Chiyoda Technol Corp，东京，日本）。该体模由一个基础体模、一个内部体模和一个由电机驱动的活塞组成。基础体模是一个直径为 180mm 的丙烯酸圆柱状体模，模拟了胸腔壁。内部体模由 20mm 厚的可变形盘状海绵组成，海绵内有 48 个 Lucite 珠和 48 根尼龙十字交叉线，用于模拟肺部的血管和支气管分叉。使用 CT 扫描仪（Aquilion LB，东芝）采集可变形体模的呼气峰值和吸气峰值图像。为了评估 CT 扫描参数对 DIR 准确性的影响，我们使用了四种管电压（80、100、120 和 135kV）和六种重建算法（FC11、FC13、FC15、FC41、FC44 和 FC52）。使用 MIM Maestro（MIM 软件，克利夫兰，美国）在两幅图像之间进行基于强度的 DIR。基于基准标记（珠子和交叉线）的靶标注册误差（TRE）用于定量评估 DIR。在不同管电压的情况下，平均 TRE 的范围为 4.44-5.69mm（重建算法：FC13）。在不同重建算法的情况下，平均 TRE 的范围为 4.26-4.59mm（管电压：120kV）。管电压和重建算法的组合会导致 TRE 差异高达 3.0mm（3.96-6.96mm）。我们的结果表明，CT 扫描参数对 TRE 有一定影响，特别是对可变形胸部体模的重建算法。
