An investigation of the physical characteristics of Ga-66 as an isotope for PET imaging and quantification
An investigation of the physical characteristics of Ga-66 as an isotope for PET imaging and quantification
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DOI：
10.1118/1.597924
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发表时间：
1997-02-01
期刊：
影响因子：
3.8
通讯作者：
Larson, SM
中科院分区：
文献类型：
--
作者：
Graham, MC;Pentlow, KS;Larson, SM
通常用于PET成像和定量的同位素具有涉及“纯"正电子（β（+））发射的直接衰变方案，即，95%-100% β（+）丰度，没有额外的伽马射线。Ga-66（E（max）=4.2 MeV，T-1/2=9.5 h）是一类具有较低丰度的β（+，）s（57%）和更复杂的光谱的同位素的成员，涉及级联发射的伽马射线的组合。这些额外的伽马射线往往会导致更高的单次率，从而导致更多的随机符合事件。光谱中最丰富的正电子（51.5%）具有PET成像所考虑的最高能量之一。对于使用Ga-66进行单克隆抗体剂量测定的目的，在开始人体研究之前，必须验证体模中的定量。在PC 4600上进行了一系列定量体模测量，PC 4600是一种基于头部优化EGO的扫描仪，具有多个探测器环。在4.0 kBq/cc至37 kBq/cc（0.11-1.0 mu Ci/cc）的浓度范围内验证了计数率线性;在直接平面和交叉平面中，x和y方向上的分辨率平均为16 mm半峰全宽。轴向分辨率为14 mm。高能正电子的范围（高达4.153 MeV，在组织中的范围为7.6 mm）被验证为分辨率退化的主要来源。在上述限度内，Ga-66是一种适合用作Ga-66柠檬酸盐或与单克隆抗体一起用于肿瘤和其他病变的检测和分期的同位素。此外，高能正电子在用作单克隆抗体标记时具有可能的治疗应用。(C)1997年美国医学物理学家协会。
Isotopes commonly used for PET imaging and quantification have a straightforward decay scheme involving ''pure'' positron (beta(+)) emission, i.e., 95%-100% beta(+) abundance, with no additional gamma rays. Ga-66 (E(max)=4.2 MeV, T-1/2=9.5 h) is a member of a category of isotopes with a lower abundance of beta(+,)s (57%) and a more complicated spectrum involving combinations of gamma rays that are emitted in cascade. These additional gamma rays tend to cause a higher singles rate, resulting in more random coincidence events. The most abundant positron (51.5%) in the spectrum has one of the highest energies considered for PET imaging. For the purposes of monoclonal antibody dosimetry using Ga-66, it is important to verify the quantification in phantoms prior to initiating human studies. A series of quantitative phantom measurements were performed on the PC4600, a head-optimized EGO based scanner with multiple detector rings. Count rate linearity was verified over concentrations ranging from 4.0 kBq/cc to 37 kBq/cc (0.11-1.0 mu Ci/cc); resolution averaged 16 mm full width half-maximum in the x and y directions in both the direct and cross planes. Axial resolution was 14 mm. The range of the energetic positrons (up to 4.153 MeV, range 7.6 mm in tissue) was verified as a primary source of resolution degradation. Within the limits outlined above, Ga-66 is a suitable isotope for use as Ga-66 citrate or with monoclonal antibodies in the detection and staging of tumors and other lesions. In addition, the energetic positrons have possible therapeutic applications when used as a monoclonal antibody label. (C) 1997 American Association of Physicists in Medicine.