Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany.
J Appl Clin Med Phys. 2022 Sep;23(9):e13727. doi: 10.1002/acm2.13727. Epub 2022 Jul 18.
A novel, mobile 3-in-1 X-ray system featuring radiography, fluoroscopy, and cone-beam computed tomography (CBCT) has been launched for brachytherapy recently. Currently, there is no quality assurance (QA) procedure explicitly applicable to this system equipped with innovative technologies such as dynamic jaws and motorized lasers. We developed a dedicated QA procedure and, based on its performance for a duration of 6 months, provide an assessment of the device's stability over time.
With the developed QA procedure, we assessed the system's planar and CBCT-imaging performance by investigating geometric accuracy, CT-number stability, contrast-noise-ratio, uniformity, spatial resolution, low-contrast detectability, dynamic range, and X-ray exposure using dedicated phantoms. Furthermore, we evaluated geometric stability by using the flexmap-approach and investigated the device's laser- and jaw-positioning accuracy with an in-house test phantom. CBCT- and planar-imaging protocols for pelvis, breast, and abdomen imaging were examined.
Planar- and CBCT-imaging performances were widely stable with a geometric accuracy ≤1 mm, CT-number stability of up to 46 HU, and uniformity variations of up to 48 HU over time. For planar imaging, low-contrast detectability and dynamic range exceeded current recommendations. Although geometric stability was considered tolerable, partly substantial positioning inaccuracies of up to more than 120 mm and -13 mm were obtained for lasers and jaws, respectively. X-ray exposure showed small variations of ≤0.56 μGy and ≤0.76 mGy for planar- and CBCT-imaging, respectively. The conductance of the QA procedure allowed a smooth evaluation of the system's overall performance.
We developed a QA workflow for a novel 3-in-1 X-ray system allowing to assess the device's imaging and hardware performance. The system showed in general a reasonable imaging performance and stability over time, whereas improvements regarding laser and jaw accuracy are strictly required.
最近推出了一种新型的移动 3-in-1 X 射线系统，具有放射照相、透视和锥形束计算机断层扫描 (CBCT) 功能。目前，尚无明确适用于配备动态口和电动激光器等创新技术的此类系统的质量保证 (QA) 程序。我们开发了一种专用的 QA 程序，并根据其在 6 个月内的性能，对设备随时间的稳定性进行评估。
使用所开发的 QA 程序，我们通过使用专用的体模研究几何精度、CT 数稳定性、对比噪声比、均匀性、空间分辨率、低对比度检测能力、动态范围和 X 射线曝光等，来评估系统的平面和 CBCT 成像性能。此外，我们使用 flexmap 方法评估了几何稳定性，并使用内部测试体模评估了设备的激光和口定位精度。还检查了骨盆、乳房和腹部成像的 CBCT 和平面成像协议。
平面和 CBCT 成像性能具有广泛的稳定性，几何精度≤1mm，CT 数稳定性高达 46HU，随时间的均匀性变化高达 48HU。对于平面成像，低对比度检测能力和动态范围超过了当前的建议。尽管认为几何稳定性是可以接受的，但对于激光和口的定位精度，分别获得了高达 120mm 以上和-13mm 的实质性定位误差。对于平面和 CBCT 成像，X 射线曝光的变化均≤0.56μGy 和≤0.76mGy。QA 程序的进行允许对系统的整体性能进行平滑评估。
我们为新型的 3-in-1 X 射线系统开发了 QA 工作流程，可用于评估设备的成像和硬件性能。该系统总体上显示出合理的成像性能和随时间的稳定性，但是需要严格提高激光和口的精度。
