Sephton R, Hagekyriakou J
Department of Physical Sciences, Peter MacCallum Cancer Institute, Melbourne, Australia.
Radiother Oncol. 1995 Jun;35(3):240-7. doi: 10.1016/0167-8140(95)01572-x.
Initial clinical experience is presented, on the use of a prototype portal imaging system which is designed to provide diagnostic-quality images on-line at the accelerator. The system comprises a compact diagnostic X-ray unit mounted on the accelerator head, with its source in the isocentric plane exactly 37 degrees around from the therapy source. The image detector is an image intensifier with digital image storage/processing facilities. Images were taken at the accelerator of treatment fields in seven patients (pelvic, head and neck, chest fields) and these images were comparable in anatomical contrast to simulator radiographs. Two techniques for marking the therapy field onto the portal images were successfully demonstrated. One was to mark relevant corners or edges of the therapy light field on the skin using small Pb markers which become clearly visible in the 'diagnostic' portal image. The other was to record a separate 'therapy' image and through the software, extract and superimpose the field edges on to the 'diagnostic' image. The system and method proved fundamentally sound on criteria of image quality, geometric precision of rotation between therapy and imaging conditions, and its potential for development as a practical clinical tool.
本文介绍了使用一种原型门静脉成像系统的初步临床经验，该系统旨在在加速器上在线提供诊断质量的图像。该系统包括一个紧凑的诊断X射线单元，安装在加速器头部，其源位于等中心平面，与治疗源成37度角。图像探测器是一个带有数字图像存储/处理设备的图像增强器。在加速器上对7名患者（盆腔、头颈部、胸部区域）的治疗野进行了成像，这些图像在解剖对比度上与模拟X线片相当。成功演示了两种在门静脉图像上标记治疗野的技术。一种是使用小铅标记在皮肤上标记治疗光野的相关角或边，这些标记在“诊断”门静脉图像中清晰可见。另一种是记录单独的“治疗”图像，并通过软件提取野边缘并叠加到“诊断”图像上。在图像质量、治疗和成像条件之间旋转的几何精度以及作为实用临床工具的发展潜力等标准方面，该系统和方法被证明在根本上是可靠的。
