Evaluation of On- and Off-Line Bioluminescence Tomography System for Focal Irradiation Guidance.
Evaluation of On- and Off-Line Bioluminescence Tomography System for Focal Irradiation Guidance.
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DOI：
10.1667/rr14423.1
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发表时间：
2016-12
影响因子：
3.4
通讯作者：
Wang KK
中科院分区：
文献类型：
--
作者：
Zhang B;Wong JW;Iordachita II;Reyes J;Nugent K;Tran PT;Tuttle SW;Koumenis C;Wang KK
针对计算机断层扫描（CT）和锥形束CT（CBCT）在辐射引导方面的局限性，特别是对于不使用造影剂的软组织靶点，我们的研究小组开发了一种解决方案，将生物发光断层扫描（BLT）作为临床前辐射研究的图像引导模式。然而，将这样的系统添加到现有的小动物辐照器不是一项小任务。一种潜在的解决方案是在辐照器附近使用离线BLT系统，在两个系统之间进行稳定有效的动物运输。在这项研究中，我们研究了离线BLT系统的定位精度时，用于小动物辐射研究平台（SARRP），并与那些在线系统的结果进行了比较。CBCT装备在离线BLT系统和SARRP上，它们之间的距离为5 m。为了评价动物在两个系统之间运输期间的设置误差，小鼠在SARRP上进行CBCT成像，然后运输到离线系统进行第二次CBCT成像。计算两个图像的归一化强度差以及相应的直方图和相关性，以评估运输过程是否干扰动物定位。观察到SARRP和离线小鼠CBCT之间的强相关性（相关系数>0.95）。在运输过程中，植入光源中心的偏移量可保持在0.2 mm以内。为了比较使用在线SARRP BLT和离线系统的目标定位精度，将自发光生物发光源植入麻醉小鼠的腹部。除了用于剂量计算之外，CBCT成像还用于生成成像小鼠的网格，用于BLT重建。设计并比较了两种方案，其涉及基于以下任一者的发光源的定位：1.在线SARRP生物发光图像和CBCT;或2.离线生物发光图像和SARRP CBCT。假设第一种情况具有最小的设置误差，因为不涉及动物运输。第二种情况检查当CBCT中存在最小目标对比度时，离线BLT系统（具有从SARRP CBCT生成的网格）是否可用于引导SARRP照射。动物在两个系统之间运输期间保持稳定性。通过离线BLT重建的光源质心（CoM）与从SARRP CBCT获得的真实CoM的偏移为1.0 ± 0.4 mm。这些结果与使用在线BLT的1.0 ± 0.2 mm偏移相当。通过SARRP提供的CBCT信息和运输过程中有效的动物固定，这些研究结果支持利用离线BLT引导系统，靠近SARRP，进行准确的软组织靶定位。此外，在本研究中还为我们在宾夕法尼亚大学的合作伙伴研究中心引入了一个专用的独立BLT系统。
In response to the limitations of computed tomography (CT) and cone-beam CT (CBCT) in irradiation guidance, especially for soft-tissue targets without the use of contrast agents, our group developed a solution that implemented bioluminescence tomography (BLT) as the image-guidance modality for preclinical radiation research. However, adding such a system to existing small animal irradiators is no small task. A potential solution is to utilize an off-line BLT system in close proximity to the irradiator, with stable and effective animal transport between the two systems. In this study, we investigated the localization accuracy of an off-line BLT system when used for the small animal radiation research platform (SARRP) and compared the results with those of an on-line system. The CBCT was equipped on both the off-line BLT system and the SARRP, with a distance of 5 m between them. To evaluate the setup error during animal transport between the two systems, the mice underwent CBCT imaging on the SARRP and were then transported to the off-line system for a second CBCT imaging session. The normalized intensity difference of the two images and the corresponding histogram and correlation were computed to evaluate if the transport process perturbed animal positioning. Strong correlation (correlation coefficients >0.95) between the SARRP and the off-line mouse CBCT was observed. The offset of the implanted light source center can be maintained within 0.2 mm during transport. To compare the target localization accuracy using the on-line SARRP BLT and the off-line system, a self-illuminated bioluminescent source was implanted in the abdomen of anesthetized mice. In addition to the application for dose calculation, CBCT imaging was also employed to generate the mesh grid of the imaged mouse for BLT reconstruction. Two scenarios were devised and compared, which involved localization of the luminescence source based on either: 1. on-line SARRP bioluminescence image and CBCT; or 2. off-line bioluminescence image and SARRP CBCT. The first scenario is assumed to have the least setup error, because no animal transport was involved. The second scenario examines if an off-line BLT system, with the mesh generated from the SARRP CBCT, can be used to guide SARRP irradiation when there is minimal target contrast in CBCT. Stability during animal transport between the two systems was maintained. The center of mass (CoM) of the light source reconstructed by the off-line BLT had an offset of 1.0 ± 0.4 mm from the true CoM derived from the SARRP CBCT. These results are comparable to the offset of 1.0 ± 0.2 mm using on-line BLT. With CBCT information provided by the SARRP and effective animal immobilization during transport, these findings support the utilization of an off-line BLT-guided system, in close proximity to the SARRP, for accurate soft-tissue target localization. In addition, a dedicated standalone BLT system for our partner site at the University of Pennsylvania was introduced in this study.