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目的:制作出体模来评估颅内肿瘤立体定向放疗中所使用的计算机断层扫描(CT)和核磁共振(MRI)影像的质量,以保证放疗的精度。方法:设计和制作出一个可用于评估的体模,并且在与放疗病人影像扫描相同的条件下,将该体模分别放在CT和MRI下进行扫描,最后在Brainlab工作站将几何参数进行对比得到MRI几何失真的大小,同时也可对融合的质量进行评估。结果:制作出的体模满足设计的要求,得到的MRI的几何失真在2mm以内,而勾画靶区体积的准确性超过99%,手工融合的误差在2 mm内,都在报道过的允许的误差范围内,满足了放疗精度的要求。结论:由于病人和机器所引起的MRI几何失真,靶区体积的误差和手工融合产生的误差是不可避免的,我们必须在一定的周期内对这些误差进行评估。实践证明,本文所介绍的体模的方法将是一种简便易行的方法。
OBJECTIVE: To generate a phantom to evaluate the quality of computed tomography (CT) and magnetic resonance imaging (MRI) used in stereotactic radiotherapy of intracranial tumors to ensure radiotherapy accuracy. Methods: A phantom that can be used for evaluation was designed and produced. The phantom was scanned under CT and MRI under the same conditions as radiotherapy patients. Finally, geometric parameters were compared at Brainlab workstation The magnitude of MRI geometric distortions can also assess the quality of the fusion. Results: The fabricated phantom met the design requirements. The geometric distortion of MRI was less than 2 mm. The accurate volume of the target volume was over 99%. The error of manual fusion was within 2 mm. All the reported allowable The error range, to meet the requirements of radiotherapy accuracy. CONCLUSIONS: Because of the geometric distortions caused by the patient and the machine, errors in volume of the target volume and errors due to manual fusion are unavoidable and we must evaluate these errors over a period of time. Practice has proved that the phantom method described in this article will be a simple and easy way.