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首页> 外文学位 >An investigation of megavoltage computed tomography using a radioactive cobalt-60 gamma ray source for radiation therapy treatment verification.
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An investigation of megavoltage computed tomography using a radioactive cobalt-60 gamma ray source for radiation therapy treatment verification.

机译：使用放射活性钴60伽玛射线源进行兆伏计算机断层扫描的研究，用于放射疗法的治疗验证。

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The use of Cobalt-60 as a radiation source in radiation therapy applications has a fifty-year long history. Unfortunately, over the last two decades, Co-60 has steadily fallen out of favour in conventional radiation therapy practice. The Medical Physics Group at the Kingston Regional Cancer Centre has aimed to modernize Cobalt-60 radiation therapy by researching its viability for delivering intensity modulated radiation therapy (IMRT) using the tomotherapy technique. An important feature of tomotherapy is the treatment geometry, which provides a convenient means to perform on-line computed tomography (CT).; In CT imaging, x-ray attenuation measurements collected from different angles around an object provide the means to reconstruct cross-sectional or volumetric images of that object. Considerable research has been done investigating megavoltage computed tomography (MVCT), where the radiation beam from a medical linear accelerator is used as the source of x-rays. The research in this thesis explores the use of Co-60 as an alternative radiation source for MVCT.; An automated bench-top image acquisition system was designed and built to examine the image quality from Co-60 gamma ray fan-beam and cone-beam MVCT images. The main components of the bench-top system include an object rotation stage, a 2-dimensional scanning diode detector apparatus, and a Co-60 radiotherapy unit. MVCT images of simple test objects acquired with the above experimental system demonstrate a 3 mm high-contrast spatial resolution, 2.8% low-contrast sensitivity, linearity between MVCT number and electron density, and an inherent absence of beam-hardening artifacts. In addition, MVCT images of human-equivalent test objects provide promising anatomical visualization, which may prove useful for accurate patient positioning prior to a radiation therapy treatment.
机译：在放射治疗应用中使用Cobalt-60作为放射源已有50年的历史。不幸的是，在过去的二十年中，Co-60逐渐在常规放射治疗实践中失宠。金斯敦地区癌症中心的医学物理学小组旨在研究Cobalt-60放射治疗的现代化，方法是研究其使用tomotherapy技术进行强度调制放射治疗（IMRT）的可行性。断层摄影的一个重要特征是治疗几何形状，它为执行在线计算机断层扫描（CT）提供了便利的手段。在CT成像中，从物体周围不同角度收集的X射线衰减测量值提供了重建该物体的横截面或体积图像的方法。在研究兆伏计算机断层扫描（MVCT）方面已经进行了相当多的研究，其中将来自医用线性加速器的辐射束用作X射线源。本文的研究探索了使用Co-60作为MVCT的替代辐射源。设计并构建了一个自动台式图像采集系统，以检查Co-60伽玛射线扇形光束和锥形束MVCT图像的图像质量。台式系统的主要组件包括物体旋转台，二维扫描二极管检测器设备和Co-60放射治疗仪。通过上述实验系统获得的简单测试对象的MVCT图像显示出3毫米的高对比度空间分辨率，2.8％的低对比度灵敏度，MVCT数与电子密度之间的线性关系以及固有的不存在束硬化伪像的特性。另外，人体等效测试对象的MVCT图像提供了有希望的解剖学可视化，这可能对放射治疗之前的准确患者定位很有用。

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