Granger W E, Bednarek D R, Rudin S
Department of Radiology, State University of New York at Buffalo 14215, USA.
Med Phys. 1997 May;24(5):703-7. doi: 10.1118/1.598077.
Fluoroscopic units can irradiate an area outside the displayed field of view (FOV) which provides no additional information to the fluoroscopist and may significantly increase the integral dose to the patient. This unnecessary exposure can be reduced using region of interest (ROI) filtration techniques to attenuate the x rays peripheral to the ROI as well as outside the displayed FOV [Granger et al., Med. Phys. 23, 1059 (1996)]. A survey was conducted to quantitatively determine the deviation between the total exposed area and the displayed FOV on 18 fluoroscopic x-ray units which have different shaped collimation. A film was taken in fluoroscopic mode and the area of the FOV was determined from the image of markers placed at the edge of the displayed FOV. For each unit, a measurement was made for each magnification mode at various source to image distances. The measured difference between the total exposed area and the area of the displayed FOV ranged between 5% and 32% for units meeting federal compliance standards and between 22% and 48% for units which were found to be out of compliance. The results of the survey and the application of ROI imaging techniques as a possible method to reduce dose due to inexact fluoroscopic collimation are presented.
荧光透视设备能够对显示视野（FOV）之外的区域进行照射，而这一区域并不能为荧光透视医师提供更多信息，且可能会显著增加患者的累积剂量。使用感兴趣区域（ROI）过滤技术，衰减ROI周边以及显示视野之外的X射线，可减少这种不必要的照射[格兰杰等人，《医学物理》23, 1059 (1996)]。开展了一项调查，以定量确定18台具有不同形状准直的荧光透视X射线设备的总照射面积与显示视野之间的偏差。在荧光透视模式下拍摄一张胶片，并根据放置在显示视野边缘的标记图像确定视野面积。对于每台设备，在不同的源到图像距离下，对每种放大模式进行测量。符合联邦合规标准的设备，总照射面积与显示视野面积之间的测量差值在5%至32%之间；而不符合标准的设备，该差值在22%至48%之间。本文介绍了该调查结果以及将ROI成像技术作为一种可能的方法来减少因荧光透视准直不准确而导致的剂量情况。
