Data of "Multi-institutional study on image quality for a novel CBCT solution on O-ring linac"

Data of "Multi-institutional study on image quality for a novel CBCT solution on O-ring linac".

Abstract
Introduction: This work presents a multi-institutional study on image quality provided by a novel cone beam computed tomography (CBCT). The main goal is to investigate the consistency of imaging performance across multiple institutions.
Methods: Phantoms for measuring relative electron density (RED) and image quality were sent to six institutions for imaging on Ethos and Halcyon units equipped with HyperSight CBCT. The imaging protocols included tube potential from 100 to 140 kVp and exposure from 80 to 800 mAs. Imaging performance was evaluated with regard to RED versus Hounsfield Units (HU), uniformity, contrast-to-noise ratio (CNR), slice thickness, circular symmetry, Modulation Transfer Function (MTF), and spatial resolution.
Results: Among all institutions, some variability was observed among institutions in the RED-to-HU relationship, especially for RED values greater than 1, although no outliers were found (|z-score|<2 in all cases). In this range, RED/HU slopes were 475 ± 25 10-6 RED/HU at 100kVp, 505 ± 20 10-6 RED/HU at 125kVp, and 550 ± 20 10-6 RED/HU at 140kVp. Radial uniformity ranged from 1 to 7 HU, depending on protocol. Circular symmetry for two points 50 mm apart showed consistency within one-pixel dimension. Integral non-uniformity was between 1 to 10, with no difference observed between vertical and horizontal dimensions. Contrast rods with 1 % gave CNR=0.5, 1 and 2 for 100(88), 125(176) and 140(528) in kVp(mAs), and contrast rods with 0.5 % had CNR=0.2, 0.4 and 0.8 for 100(88), 125(176) and 140(528) in kVp(mAs). Spatial resolution given by MTF at 10 % and 50 % yielded values of 0.55 ± 0.01 mm-1 and 0.35 ± 0.02 mm-1, respectively.
Conclusions: This multi-institutional analysis of CBCT imaging performance showed consistency in radial uniformity, circular symmetry, integral non-uniformity, contrast and spatial resolution. Some variability was seen in the RED-to-HU relationship for RED>1 depending on exposure. More data from different institutions would be necessary to establish more robust statistical metrics which ensure quality parameters.

Agulles-Pedrós L, MacDonald RL, Cherpak AJ, et al.Multi-institutional study on image quality for a novel CBCT solution on O-ring linac. J Appl Clin Med Phys. 2025;e70023.
https://doi.org/10.1002/acm2.70023

数据集：O形环直线加速器新型锥形束计算机断层扫描（CBCT）成像质量多中心研究

摘要
引言：本研究针对一款新型锥形束计算机断层扫描（CBCT）系统的成像质量开展多中心探索，核心目标为探究不同中心间成像性能的一致性。
方法：将用于测量相对电子密度（RED）与成像质量的体模送至6家中心，在搭载HyperSight CBCT的Ethos及Halcyon直线加速器设备上完成成像扫描。成像参数涵盖100~140 kVp的管电压，以及80~800 mAs的曝光剂量。分别从相对电子密度与亨氏单位（HU）的对应关系、均匀性、对比度噪声比（CNR）、层厚、圆周对称性、调制传递函数（MTF）以及空间分辨率等维度评估成像性能。
结果：所有参与中心的RED与HU对应关系均存在一定程度的中心间差异，尤其在RED＞1的区间内，不过未发现异常值（所有病例的|Z得分|<2）。该区间内，100kVp下RED/HU斜率为475 ± 25 ×10^-6 RED/HU，125kVp下为505 ± 20 ×10^-6 RED/HU，140kVp下为550 ± 20 ×10^-6 RED/HU。径向均匀性随成像方案不同介于1~7 HU之间。间距50mm的两点圆周对称性一致性可达单像素级别。积分非均匀性范围为1~10，垂直与水平维度未观察到显著差异。对比度模体杆对比度为1%时，在100(88)、125(176)、140(528) kVp(mAs)参数下的CNR分别为0.5、1和2；对比度为0.5%时，对应参数下的CNR分别为0.2、0.4和0.8。由MTF得到的10%与50%截止空间分辨率分别为0.55 ± 0.01 mm^-1和0.35 ± 0.02 mm^-1。
结论：本次CBCT成像性能多中心分析结果显示，径向均匀性、圆周对称性、积分非均匀性、对比度及空间分辨率均具有良好的中心间一致性。在RED＞1的区间内，RED与HU的对应关系随曝光剂量存在一定差异。未来需纳入更多不同中心的数据，以建立更稳健的统计指标来保障成像质量参数的可靠性。

参考文献：Agulles-Pedrós L, MacDonald RL, Cherpak AJ, 等. O形环直线加速器新型CBCT成像质量多中心研究. 《应用临床医学物理杂志》, 2025;e70023. https://doi.org/10.1002/acm2.70023