Ding K, Deng J, Du K, Cao K, Christensen G, Reinhardt J, Sheng K, Libby B, Benedict S, Lamer J, Chen Q
University of Virginia, Charlottesville, VA.
University of Iowa, Iowa City, IA.
Med Phys. 2012 Jun;39(6Part3):3615. doi: 10.1118/1.4734677.
Recent clinical trials and animal studies have indicated that the tissue sensitivity to radiation induced lung injury (RILI) may be region- specific. In this study, we propose a new 4D cone beam CT (CBCT) basedcompliance imaging method to measure regional pulmonary function change in precisely irradiated small animal under CBCT guidance on small animal radiation research platform (SARRP) to facilitate our understanding of region-specific tissue sensitivity to RILI.
Four Sprague-Dawley rats underwent prospective pressure gated 4D CBCT on SARRP. Three animals were selected as control group which underwent a second 4D CBCT scan. The fourth animal was irradiated in the central lung (24 Gy) using 3 × 3 mm collimating cone 2 months prior to the scan. The specific compliance (Csp) was calculated via the real time pressure measurement from the ventilator and displacement field from 3D B-spline image registration between the end of inhale and end of exhale phases from the 4D CBCT scan. The 3D Csp maps from the control animal group were mapped to the irradiated animal as a Csp functional atlas for statistical analysis. We alsoevaluated the repeatability of the Csp measurement on a voxel-by-voxel basis.
No significant Csp difference is found after two month of radiation between the irradiated rat (0.22±0.05) and the functional atlas (0.21±0.07). The observation is consistent with previous publications. The averaged linear correlation coefficient between the voxel-by-voxel Csp measurements from initial and repeat scans in control group is 0.98.
We proposed a method that uses 4D CBCT based compliance imaging to measure region-specific tissue sensitivity of RILI. We compared the irradiated animal two months after radiation with the control group. Our study shows an excellent robustness of the proposed method for regional lung tissue specific compliance measurement. This work was supported in part by UVa George Amorino Pilot Grant.
近期的临床试验和动物研究表明，组织对放射性肺损伤（RILI）的敏感性可能具有区域特异性。在本研究中，我们提出了一种基于4D锥形束CT（CBCT）的顺应性成像新方法，用于在小动物辐射研究平台（SARRP）的CBCT引导下，精确测量受辐照小动物的区域肺功能变化，以促进我们对RILI区域特异性组织敏感性的理解。
4只Sprague-Dawley大鼠在SARRP上进行前瞻性压力门控4D CBCT检查。选择3只动物作为对照组，进行第二次4D CBCT扫描。第四只动物在扫描前2个月使用3×3 mm准直锥对肺中央进行照射（24 Gy）。通过呼吸机实时压力测量以及4D CBCT扫描吸气末和呼气末阶段之间3D B样条图像配准得到的位移场来计算比顺应性（Csp）。将对照组动物的3D Csp图映射到受辐照动物上，作为Csp功能图谱进行统计分析。我们还逐体素评估了Csp测量的可重复性。
辐照大鼠（0.22±0.05）与功能图谱（0.21±0.07）在辐射2个月后未发现显著的Csp差异。该观察结果与先前的出版物一致。对照组初始扫描和重复扫描的逐体素Csp测量之间的平均线性相关系数为0.98。
我们提出了一种基于4D CBCT顺应性成像的方法来测量RILI的区域特异性组织敏感性。我们将辐照后2个月的受辐照动物与对照组进行了比较。我们的研究表明，所提出的方法在区域肺组织特异性顺应性测量方面具有出色的稳健性。本研究部分得到弗吉尼亚大学乔治·阿莫里诺试点基金的支持。
