Physical phantom evaluation of simultaneous ^99mTc/¹²³I SPECT imaging

详细信息    查看全文

• 作者：Bang-Hung Yang^a ; ^b ; Shyh-Jen Wang^b ; Jhih-Shian Lee^a ; Meei-Ling Jan^c ; Chia-Jung Chang^a ; Jyh-Cheng Chen^a ; ^d ; ^{jcchen@ym.edu.tw}
• 关键词：Dual-isotope ; Simultaneous ; Cross-talk ; Wavelet ; Independent components analysis ; SPECT
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2011
• 出版时间：1 October, 2011
• 年：2011
• 卷：652
• 期：1
• 页码：744-746
• 全文大小：1K

文摘

Simultaneous dual-isotope imaging from two different energy gamma rays such as ^99mTc and ¹²³I is a promising technology in nuclear medicine. Its advantages are to abbreviate the acquisition procedure with an identical geometrical registration of the different isotope images, the same physiological condition without motion artifacts, and help patient throughput and comfort. However, the energy photopeaks of ^99mTc and ¹²³I radionuclides are very close. We had developed a new approach for accurate cross-talk and scatter corrections in simultaneous ^99mTc/¹²³I based on independent components analysis (ICA). Nevertheless, a large number of input energy windows are required as ICA input components, which is not useful in clinical application because commercial cameras have only 3-8 energy windows. The aim of this work was to design a new method through wavelet transformation followed by ICA with multiple energy windows (W_eICA) for cross-talk and scatter correction using a smaller number of energy windows in clinical use.

There were three cylinders (A-C) with identical volume of 20 ml. Cylinder A was filled with ^99mTc solution of 18.5 MBq, cylinder B with ¹²³I solution of 18.5 MBq, and cylinder C with ^99mTc solution of 55.5 MBq. The Image matrix size was 128¡Á128 and pixel size was 3.9 mm. Three kinds of images were acquired by energy window setting. (1) For single-isotope imaging only, energy windows of 20 % centered at 140 keV for ^99mTc and at 159 keV for ¹²³I were used. (2) In the asymmetric energy window method (AEW), energy window of 15 % centered at 140 keV for ^99mTc in conjunction with 10 % asymmetric energy window in an upper bound at 159 keV for ¹²³I was acquired. (3) Then we set six energy windows with 15 keV width ranging from 83 to 173 keV to form six images as input components of ICA. After the W_eICA method derived ^99mTc/¹²³I images alone, we compared the images from the W_eICA approach and the AEW method.

In the results, the recovery rate of ^99mTc was 1.03 and that of ¹²³I was 1.07 from the W_eICA method. Besides, the recovery rate of ^99mTc was 0.84 and that of ¹²³I was 1.05 from the AEW approach. According to our results, the W_eICA method not only decreased the number of energy windows but also separated dual-isotope photopeaks successfully. The results have demonstrated that the W_eICA method improved the quantitative accuracy and might be an effective tool for simultaneous dual-isotope SPECT imaging.