Larsson A, Johansson L, Sundström T, Ahlström K Riklund
Radiation Physics, Department of Radiation Sciences, Umeå University, SE 901 87 Umeå, Sweden.
Nucl Med Commun. 2003 Apr;24(4):411-20. doi: 10.1097/00006231-200304000-00011.
A method for attenuation and scatter correction of brain single photon emission computed tomography (SPECT) is described where computed tomography (CT) images of the brain are used for the calculation of attenuation maps. The method is evaluated for the substance 99mTc hexamethylpropylene amine oxime. A transmission dependent scatter correction is utilized and is based on ray sums calculated through the attenuation map. A method based on external markers is used to align the SPECT and CT image volumes. The markers need only to be present during the SPECT acquisition since the corresponding landmarks can be found without markers on the CT images. The mismatching has been investigated for five patients who have undergone both a CT examination and a SPECT examination with markers. Twelve individuals from the staff have pointed out the landmarks on the CT images, with an average standard deviation of 3.4 mm. Reconstructions with an attenuation map shifted the corresponding 95% confidence interval have been performed to obtain an estimation of the quantitative uncertainty caused by the mismatching, and quantitative errors of up to 6.3% have been measured. At present the method is probably most useful when groups of patients are studied.
描述了一种用于脑单光子发射计算机断层扫描（SPECT）衰减和散射校正的方法，其中利用脑的计算机断层扫描（CT）图像来计算衰减图。该方法针对99mTc六甲基丙烯胺肟这种物质进行了评估。采用了基于传输的散射校正，其基于通过衰减图计算的射线和。使用一种基于外部标记的方法来对齐SPECT和CT图像体积。由于在CT图像上无需标记就能找到相应的地标，所以标记仅需在SPECT采集期间存在。对五名同时进行了带标记的CT检查和SPECT检查的患者的配准失配情况进行了研究。十二名工作人员指出了CT图像上的地标，平均标准差为3.4毫米。已进行了带有偏移相应95%置信区间的衰减图的重建，以获得对由配准失配引起的定量不确定性的估计，并且测量到的定量误差高达6.3%。目前，当研究患者群体时，该方法可能最为有用。
