Parsai E I, Ayyangar K M, Dobelbower R R, Siegel J A
Department of Radiation Therapy, Medical College of Ohio, Toledo 43699-0008, USA.
J Nucl Med. 1997 Feb;38(2):319-24.
Infusional brachytherapy for treatment of neoplasms, with colloidal 32P has been used to treat various tumors in the pancreas, liver, brain, lung, and head and neck. In performing such treatments, anatomical verification of the location of the administered 32P from the image obtained by Bremsstrahlung SPECT alone is not possible due to the lack of internal landmarks, since the radionuclide is distributed only in the tumor and does not usually accumulate in the normal organs. The purpose of this study was to provide a practical three-dimensional approach for image fusion between Bremsstrahlung SPECT and CT.
The tumors in four cancer patients were injected directly with 32P under CT guidance. A Bremsstrahlung SPECT study using 99mTc backscatter sources to obtain the body contour was then performed. SPECT images were used to generate the skin contours using a threshold detection method. A three-dimensional surface was generated from these contours using a tiling program and fused with a corresponding CT surface generated from a CT scan in the same patient through an iterative surface-fitting algorithm. The three-dimensional surface of the region of high-activity, corresponding to the infused tumor, was then generated using the Bremsstrahlung SPECT data by mapping the iso-count surfaces through a computer program. The three-dimensional image of the organ then was fused with the registered CT-SPECT datasets.
The accuracy of fit measured as the mean distance between the SPECT and CT surfaces was in the range of 3-4 mm.
The anatomical co-registration of Bremsstrahlung SPECT with CT images using the outer surface-fitting algorithm is a reliable tool. This correlation permits direct anatomic confirmation of the region of the 32P activity distribution with the anatomic site selected for injection.
使用胶体32P进行肿瘤的灌注近距离放射治疗已被用于治疗胰腺、肝脏、脑、肺以及头颈部的各种肿瘤。在进行此类治疗时，由于缺乏内部标志物，仅通过韧致辐射单光子发射计算机断层显像（Bremsstrahlung SPECT）获得的图像无法对注入的32P的位置进行解剖学验证，因为放射性核素仅分布在肿瘤中，通常不会在正常器官中蓄积。本研究的目的是提供一种实用的三维方法，用于韧致辐射SPECT与计算机断层扫描（CT）之间的图像融合。
在CT引导下，对4例癌症患者的肿瘤直接注射32P。然后进行使用99mTc反向散射源的韧致辐射SPECT研究以获取身体轮廓。使用阈值检测方法，利用SPECT图像生成皮肤轮廓。使用平铺程序从这些轮廓生成三维表面，并通过迭代表面拟合算法与同一患者CT扫描生成的相应CT表面融合。然后通过计算机程序映射等计数表面，利用韧致辐射SPECT数据生成对应于注入肿瘤的高活性区域的三维表面。然后将器官的三维图像与配准的CT - SPECT数据集融合。
以SPECT和CT表面之间的平均距离衡量的拟合精度在3 - 4毫米范围内。
使用外表面拟合算法将韧致辐射SPECT与CT图像进行解剖学配准是一种可靠的工具。这种相关性允许对32P活性分布区域与选定注射的解剖部位进行直接解剖学确认。
