Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research.
Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research.
复制标题
用于临床前辐射研究的集成 X 射线和光学断层扫描系统的系统校准。
DOI：
10.1118/1.4914860
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发表时间：
2015
期刊：
影响因子：
3.8
通讯作者：
Wong,JohnW
中科院分区：
文献类型：
--
作者：
Yang,Yidong;Wang,KenKang-Hsin;Eslami,Sohrab;Iordachita,IulianI;Patterson,MichaelS;Wong,JohnW
锥形束计算机断层扫描（CBCT）引导的小动物放射治疗研究平台（SARRP）已被开发用于局部肿瘤照射，允许实验室研究人员以以前不可行的方式测试可以改变放射治疗结果的基本生物学假设。CBCT提供了良好的骨与软组织对比度，但无法区分肿瘤与周围软组织。生物发光断层扫描（BLT），相反，允许直接可视化，甚至亚可触及的肿瘤和肿瘤反应的定量评价。BLT与CBCT的整合提供了互补的图像信息，CBCT描绘解剖结构，BLT区分发光肿瘤。本研究是开发一种系统的方法来校准集成CBCT和BLT成像系统，可以通过板载的SARRP引导病灶tumor irradiation.MethodsThe集成成像系统包括CBCT，扩散光学断层扫描（DOT），和BLT。从CBCT获得的解剖结构和从DOT获得的光学特性作为后续BLT重建的优先信息。设计了校准器并开发了校准CBCT、DOT/BLT和整个集成系统的程序。对CBCT系统进行了几何标定。平场校正用于校正光学成像系统的非均匀响应。进行绝对发射率校准，将相机读数转换为体模或动物表面的发射率，这使得能够直接重建生物发光源强度。体模和小鼠成像进行验证calibration.ResultsAll校准程序成功地进行。细线和安乐死小鼠的CBCT均未显示空间伪影，验证了CBCT校准的准确性。使用650 nm激光源验证了绝对发射度校准，导致模拟和测量信号之间的差异为3.0%。整个系统的校准通过放置在组织模拟光学体模内的生物发光源的CBCT和BLT重建来确认。使用空间区域约束，源位置重建误差小于1 mm，源强度重建误差小于24%.ConclusionsA实用和系统的方法已经开发出校准集成的X射线和光学层析成像系统，包括相应的CBCT和光学层析成像系统校准和整个系统的几何校准。该方法可以修改和采用，以校准CBCT和光学断层扫描系统，独立或混合X射线和光学断层扫描成像系统。
PurposeThe cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation.MethodsThe integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve asa prioriinformation for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration.ResultsAll calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3.0% difference between simulated and measured signal. The calibration of the entire system was confirmed through the CBCT and BLT reconstruction of a bioluminescence source placed inside a tissue‐simulating optical phantom. Using a spatial region constraint, the source position was reconstructed with less than 1 mm error and the source strength reconstructed with less than 24% error.ConclusionsA practical and systematic method has been developed to calibrate an integrated x‐ray and optical tomography imaging system, including the respective CBCT and optical tomography system calibration and the geometrical calibration of the entire system. The method can be modified and adopted to calibrate CBCT and optical tomography systems that are operated independently or hybrid x‐ray and optical tomography imaging systems.