Dual kV/MV Imaging for Metal Artifact Reduction

描述（由申请人提供）：癌症的现代放射治疗严重依赖于计算机化逆向治疗计划，其通常使用诊断CT图像作为输入数据来描绘解剖结构并计算优化的调强放射治疗（IMRT）计划。图像引导的放射治疗还需要良好的CT图像质量来验证患者定位并识别肿瘤收缩。然而，金属的存在，例如患者的髋关节植入物或牙科手术，会导致诊断和锥束kV-CT中的图像伪影，严重影响治疗计划。由于金属对高能光子的吸收相对较低，兆伏CT基本上没有这种金属伪影，但以精确治疗计划所必需的不良软组织描绘为代价。我们的假设是，诊断锥束CT成像与有限的兆伏CT数据采集的组合可以在很大程度上消除这些金属伪影从复合CT数据集，在成本效益和剂量效率的方式。我们将设计和优化一种新型的、高DQE、薄条、MV闪烁体，该闪烁体放置在标准电子射野成像设备上，并与靶向多叶准直器控制相结合。将通过以下具体目标对多模式方法中显著改善的图像引导放射治疗干预的假设进行检验：1）研制DQE（0）> 25%、分辨力为8lp/cm的MV条带探测器; 2）研制新的硬件控制软件;图像校正和重建，从小于100 mGy的组合剂量提供120 Hounsfield单位的精度，以及3）在对至少80名癌症患者的初步体内临床研究中验证放射疗法治疗计划的改进。这些进展迅速转化为临床实践，应大大提高IMRT计划和图像引导的准确性，对于那些患者的金属物体或附近的治疗领域，导致显着降低发病率与改善局部肿瘤控制相结合。这项研究的潜在影响超出了这里列出的应用，包括受金属植入物（如脊柱棒）影响的其他治疗领域，以及骨科植入物附近的定量CT成像。

DESCRIPTION (provided by applicant): Modern radiotherapy of cancer relies heavily on computerized inverse treatment planning, which typically uses diagnostic CT images as input data to delineate anatomy and compute optimized intensity modulated radiotherapy (IMRT) plans. Image guided radiotherapy also requires good CT image quality to verify patient positioning and to identify tumor shrinkage. However the presence of metal, for example hip implants or dental work in the patient, causes image artifacts in diagnostic and conebeam kV-CT that severely impact treatment planning. Megavoltage CT is largely free of such metal artifacts due to the relatively low absorption of high energy photons by metal, but at the expense of poor soft tissue delineation essential to accurate treatment planning. Our hypothesis is that the combination of diagnostic cone beam CT imaging with limited megavoltage CT data acquisition can largely eliminate these metal artifacts from a composite CT data set, in a cost effective and dose-efficient manner. We will design and optimize a novel, high DQE, thin strip, MV scintillator placed on a standard Electronic Portal Imaging Device in combination with targeted multi-leaf collimator control. This hypothesis of significantly improved, image guided radiotherapy intervention in a multi-modal approach will be tested with the following specific aims: 1) develop the MV strip detector with a DQE(0) > 25% and a resolving power of 8 lp/cm, 2) develop new software for hardware control, image correction and reconstruction that provides 120 Hounsfield unit accuracy from a combined dose of less than 100 mGy, and 3) validate the radiation therapy treatment plan improvement in a preliminary in-vivo clinical study on at least 80 cancer patients. The rapid translation of these advances into clinical practice should greatly improve the accuracy of IMRT planning and image guidance, for those patients with metal object in or near their treatment fields, leading to significantly reduced morbidity combined with improved local tumor control. The potential impact of this research extends beyond the applications listed here, to include other therapy treatment fields affected by metallic implants such as spinal rods, as well as quantitative CT imaging in the vicinity of orthopaedic implants.