Department of Radiation Oncology, Shandong Tumor Hospital Jinan, China.
Department of Radiation Medicine and Protection, Medical College of Soochow University Suzhou, China.
Thorac Cancer. 2014 Jan;5(1):68-73. doi: 10.1111/1759-7714.12055. Epub 2014 Jan 2.
On-board kilovoltage (KV) cone-beam computed tomography (CBCT) images are used predominantly for the setup of patients' positioning. The image data can also potentially be used for dose calculation with the precise calibration of Hounsfield units (HU) to electron density (HU-density). CBCT calibration was analyzed in this study. A clinical treatment planning system was employed for CT and KV CBCT image to dose calculations and subsequent comparisons. Two HU-density tables were generated using the Computerized Imaging Reference Systems (CIRS) phantom. The results showed that a maximum ∼4% dose discrepancy was observed for inserts. The single field isodose curves were very close. The lung clinical patient study indicated that the volume of lung tumor that achieved the prescribed dose in CBCT was lower than in the CT plan. Our study showed that the dosimetric accuracy of CBCT-based dose calculation for lung tumor is acceptable only for the purpose of dosimetric checks with calibration applied. KV CBCT images cannot replace traditional CT images for dose calculation accuracy.
机载千伏（kV）锥形束计算机断层扫描（CBCT）图像主要用于患者定位的设置。图像数据也可以通过精确校准亨氏单位（HU）到电子密度（HU-density）来用于剂量计算。本研究分析了 CBCT 校准。使用计算机成像参考系统（CIRS）体模对 CT 和 KV CBCT 图像进行剂量计算和后续比较。使用 CIRS 体模生成了两个 HU-density 表。结果表明，对于插入物，观察到最大约 4%的剂量差异。单野等剂量曲线非常接近。肺部临床患者研究表明，CBCT 中达到规定剂量的肺部肿瘤体积低于 CT 计划。我们的研究表明，只有在应用校准进行剂量检查的情况下，基于 CBCT 的剂量计算的剂量学准确性才能用于肺部肿瘤，不能用于剂量计算的准确性。kV CBCT 图像不能代替传统 CT 图像用于剂量计算的准确性。
