Dual kV/MV Imaging for Metal Artifact Reduction

描述(申请人提供)：现代癌症放射治疗在很大程度上依赖于计算机化的反向治疗计划，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。图像引导放射治疗也需要良好的CT图像质量，以验证患者的位置和识别肿瘤缩小。然而，金属的存在，例如患者的髋关节植入物或牙科工作，会导致诊断和锥束千伏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，Megavolage CT在很大程度上没有这种金属伪影，但代价是准确的治疗计划所必需的较差的软组织描绘。我们的假设是，结合诊断锥束CT成像和有限的兆伏CT数据采集，可以以经济有效和剂量高效的方式从复合CT数据集中很大程度上消除这些金属伪影。我们将设计和优化一种新型的、高DQE、薄带状、中压闪烁体，放置在标准的电子门户成像设备上，并结合定向多叶准直器控制。这一假设得到显著改进，将以一种多模式方法进行图像引导放射治疗干预，其具体目标如下：1)开发DQE(0)&gt；25%、分辨率为8 lp/cm的MV条状探测器；2)开发用于硬件控制、图像校正和重建的新软件，以提供120 Hounsfield单位精度(从低于100 mGY的联合剂量)，以及3)在至少80名癌症患者的初步体内临床研究中验证放射治疗计划的改进。将这些进展迅速转化为临床实践，将大大提高IMRT计划和图像引导的准确性，对于那些在治疗区域或附近有金属物体的患者，在改善局部肿瘤控制的同时，显著降低发病率。这项研究的潜在影响超出了这里列出的应用范围，包括受金属植入物影响的其他治疗领域，如脊柱棒，以及骨科植入物附近的定量CT成像。 公共卫生相关性：癌症的现代放射治疗依赖于计算机自动生成复杂的放射治疗计划，以确保仅向肿瘤提供正确的剂量。这些计划的准确性严重依赖于癌症区域诊断X射线CT图像的清晰度。接受头颈部癌症放射治疗的患者中，有很大一部分人的牙齿充满了金属汞合金或覆盖着金冠，前列腺癌患者可能有人工髋关节，这两种情况都会降低CT图像的质量和由此产生的治疗计划的准确性。我们计划通过设计和建造一种新的组合千伏成像系统来克服这一限制，该系统可以提供出色的图像，而不需要显著增加患者的剂量。

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. PUBLIC HEALTH RELEVANCE: Modern radiation therapy treatment of cancer depends on the automated computer generation of complex radiation delivery treatment plans to ensure that the correct dose is delivered only to the tumor. The accuracy of these plans is critically dependent on the clarity of the diagnostic X-ray CT images of the cancer region. A large fraction of the patients who receive radiation therapy of head and neck cancer have teeth filled with metal amalgams or covered with gold crowns, and those with prostate cancer may have artificial hips, both of which degrade the quality of the CT images and the accuracy of the resulting treatment plans. We plan to overcome this limitation by designing and building a new, combined kV/MV imaging system that provides excellent images without requiring a significant increase in dose to the patient.