Nilas L, Hassager C, Christiansen C
Department of Clinical Chemistry, Glostrup Hospital, University of Copenhagen, Denmark.
Bone Miner. 1988 Mar;3(4):305-15.
We have investigated the long-term in vivo precision of a dual photon spine scanner using three different Gd sources and compared it with that of the single photon scanner. Standard values were significantly different with the three Gd sources. With the second there was also a systematic increase of 2% per 60,000 cps in the 44 KeV channel as the source decayed, whereas no such shift was found with the other two sources. This resulted in a significant in vivo intrasource (P less than 0.05) and intersource (P less than 0.01) variation and a six-month reproducibility ranging from 3.7 to 8.1%. After correction for these systematic errors the clinically important 2-year reproducibility in 26 premenopausal women was 3.4 +/- 1.3% for spinal BMC and 3.7 +/- 1.7% for spinal BMD. In comparison, the forearm single photon scanner had a long-term precision of 1.0 +/- 0.3%. With the presented techniques spinal measurements may therefore require 11.6 times (3.4(2):1.0(2] as many participants as the forearm measurements to detect the same changes in bone mass.
我们使用三种不同的钆源研究了双光子脊柱扫描仪的长期体内精度，并将其与单光子扫描仪的精度进行了比较。三种钆源的标准值存在显著差异。对于第二种钆源，随着源的衰减，在44千电子伏特通道中每60,000计数每秒会有2%的系统性增加，而其他两种钆源未发现这种偏移。这导致了显著的体内源内（P小于0.05）和源间（P小于0.01）变化，以及六个月的再现性范围为3.7%至8.1%。在校正这些系统误差后，26名绝经前女性中临床上重要的两年脊柱骨矿含量（BMC）再现性为3.4±1.3%，脊柱骨密度（BMD）再现性为3.7±1.7%。相比之下，前臂单光子扫描仪的长期精度为1.0±0.3%。因此，使用所介绍的技术，脊柱测量可能需要前臂测量参与者数量的11.6倍（3.4²:1.0²）才能检测到相同的骨量变化。
