Wilson R A, Kopiwoda S Y, Callahan R J, Moore R H, Boucher C A, Manspeaker H, Castronovo F P, Strauss H W
Eur J Nucl Med. 1987;13(2):82-5. doi: 10.1007/BF00256021.
178Ta is a short lived radionuclide (half life = 9.3 min), which results in favorable radiation exposure compared to 99mTc (half life 6 h). The energy spectrum of 178Ta consists of imageable photons in the 55-65 keV (61.2%) and 93 keV (33.7%) range but also 6% of disintegrations result in photons with energies greater than 500 keV. These high energy photons cause septal penetration in low energy collimators so that resolution is degraded. However, a medium energy collimator prevents the septal penetration of these higher energy photons. Serial blood samples obtained from dog and rabbit models indicate that 178Ta is retained in the blood pool for at least 20-30 min after intravenous injection. The 178Ta appears to be associated with the protein fraction of the plasma and not primarily with the red blood cell fraction as determined by centrifugation and column chromatography. Gated equilibrium blood pool images using 178Ta were comparable in quality to images using the 99mTc labelled red blood cell technique. Therefore, 178Ta may allow comparable equilibrium gated blood pool imaging with much more favorable radiation dosimetry. Thus, serial studies over prolonged periods of observation may be obtained.
178Ta是一种半衰期较短的放射性核素（半衰期 = 9.3分钟），与99mTc（半衰期6小时）相比，其辐射暴露情况更有利。178Ta的能谱由55 - 65 keV（61.2%）和93 keV（33.7%）范围内可成像的光子组成，但也有6%的衰变会产生能量大于500 keV的光子。这些高能光子会导致低能准直器中的隔板穿透，从而使分辨率降低。然而，中能准直器可防止这些高能光子的隔板穿透。从狗和兔子模型获取的系列血样表明，静脉注射后178Ta在血池中的保留时间至少为20 - 30分钟。通过离心和柱色谱法测定，178Ta似乎与血浆中的蛋白质部分相关，而不是主要与红细胞部分相关。使用178Ta的门控平衡血池图像在质量上与使用99mTc标记红细胞技术的图像相当。因此，178Ta可能允许进行具有更有利辐射剂量学的可比平衡门控血池成像。这样，就可以在较长的观察期内进行系列研究。
