Performance measurement of the microPET focus 120 scanner
Performance measurement of the microPET focus 120 scanner
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DOI：
10.2967/jnumed.107.040550
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发表时间：
2007-09-01
影响因子：
9.3
通讯作者：
Moon, Dae Hyuk
中科院分区：
文献类型：
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作者：
Kim, Jin Su;Lee, Jae Sung;Moon, Dae Hyuk
microPET Focus 120扫描仪是第三代动物PET扫描仪，专用于啮齿动物成像。在这里，我们报告扫描仪性能测试的结果。方法：用Ge-68点源测量能量分辨率，测量每个晶体的能量分辨率并取平均值。使用Na-22点源测量空间分辨率，该点源在系统中心和各种偏离中心的位置处具有0.25 mm的标称尺寸。通过外推使用F-18线源和多层吸收体测量的数据来确定没有衰减的绝对灵敏度。用两种不同的圆柱体模拟大鼠和小鼠身体，测量散射分数和计数率性能。灵敏度，散射分数，和噪声等效计数率（NECR）的实验重复4种不同的条件下（能量窗口，250类似于750 keV或350类似于650 keV;符合窗口，6或10 ns）。扫描了带有各种尺寸热棒插入件的性能体模，并进行了几项动物研究。结果：在511 keV峰值处的能量分辨率平均为18.3%。采用傅立叶重组（FBM）和滤波反投影（FBP）算法重建的图像的径向、切向和轴向分辨率在中心为1.18（径向）、1.13（切向）和1.45 mm半高全宽（FWHM）（轴向），在径向偏移为2 cm时为2.35（径向）、1.66（切向）和2.00 mm FWHM（轴向）。横轴和轴向中心的绝对灵敏度分别为7.0%（250与750 keV相似，10 ns）、6.7%（250与750 keV相似，6 ns）、4.0%（350与650 keV相似，10 ns）和3.8%（350与650 keV相似，6 ns）。散射分数为15.9%（小鼠体模）和35.0%（大鼠体模）为250类似于750 keV和6 ns。峰值NECR在3，242 kBq/mL（小鼠体模）下为869 kcps，在250 kBq/mL（大鼠体模）下为228 kcps，类似于750 keV和6 ns。1.6 mm直径的热棒插入物被明确识别，动物研究说明了该系统用于研究整个啮齿动物和中型动物大脑的可行性。结论：该独立现场测试的结果表明，F120扫描仪的物理特性优于之前的microPET系列系统。该系统将有助于小型啮齿动物和大型动物大脑的成像研究。
The microPET Focus 120 scanner is a third-generation animal PET scanner dedicated to rodent imaging. Here, we report the results of scanner performance testing. Methods: A Ge-68 point source was used to measure energy resolution, which was determined for each crystal and averaged. Spatial resolution was measured using a Na-22 point source with a nominal size of 0.25 mm at the system center and various off-center positions. Absolute sensitivity without attenuation was determined by extrapolating the data measured using an F-18 line source and multiple layers of absorbers. Scatter fraction and counting rate performance were measured using 2 different cylindric phantoms simulating rat and mouse bodies. Sensitivity, scatter fraction, and noise equivalent counting rate (NECR) experiments were repeated under 4 different conditions (energy window, 250 similar to 750 keV or 350 similar to 650 keV; coincidence window, 6 or 10 ns). A performance phantom with hot-rod inserts of various sizes was scanned, and several animal studies were also performed. Results: Energy resolution at a 511 -keV photopeak was 18.3% on average. Radial, tangential, and axial resolution of images reconstructed with the Fourier rebinning (FORE) and filtered backprojection (FBP) algorithms were 1.18 (radial), 1.13 (tangential), and 1.45 mm full width at half maximum (FWHM) (axial) at center and 2.35 (radial), 1.66 (tangential), and 2.00 mm FWHM (axial) at a radial offset of 2 cm. Absolute sensitivities at transaxial and axial centers were 7.0% (250 similar to 750 keV, 10 ns), 6.7% (250 similar to 750 keV, 6 ns), 4.0% (350 similar to 650 keV, 10 ns), and 3.8% (350 similar to 650 keV, 6 ns). Scatter fractions were 15.9% (mouse phantom) and 35.0% (rat phantom) for 250 similar to 750 keV and 6 ns. Peak NECR was 869 kcps at 3,242 kBq/mL (mouse phantom) and 228 kcps at 290 kBq/mL (rat phantom) at 250 similar to 750 keV and 6 ns. Hot-rod inserts of 1.6-mm diameter were clearly identified, and animal studies illustrated the feasibility of this system for studies of whole rodents and mid-sized animal brains. Conclusion: The results of this independent field test showed the improved physical characteristics of the F120 scanner over the previous microPET series systems. This system will be useful for imaging studies on small rodents and brains of larger animals.