Dudley N J, Griffith K, McGill G P, Rogers A T
Medical Physics & IT Services, City Hospital, Nottingham, UK.
Eur J Nucl Med. 1995 Apr;22(4):335-8. doi: 10.1007/BF00941850.
Measurement or estimation of the activity of krypton-81m administered to a patient during lung ventilation imaging is difficult, due to the short half-life and continuous delivery via pipework, and no satisfactory method exists. Calculations based on generator activity have the disadvantages that this activity may not be accurately known and that not all activity eluted is inhaled by the patient. The aim of this study was to develop a simple method for estimating the administered activity from the number of counts in each patient image. A formula based on the ratio of counts in 81mKr and technetium-99m lung ventilation and perfusion images was developed and reduced so that administered activity could be directly calculated from the total 81mKr counts, the 99mTc count rate, the administered activity of 99mTc and a constant representing the ratio of counts expected from equal activities of each radioisotope. The formula allows a direct calculation from the image acquisition data following an initial set of experimental work to establish the constant for a particular gamma camera and collimator system.
在肺部通气成像过程中，对给予患者的81m氪活度进行测量或估算很困难，这是因为其半衰期短且通过管道持续输送，并且不存在令人满意的方法。基于发生器活度的计算存在以下缺点：该活度可能无法准确得知，而且并非所有洗脱的活度都被患者吸入。本研究的目的是开发一种简单的方法，根据每个患者图像中的计数来估算给予的活度。基于81m氪和锝-99m肺部通气及灌注图像中的计数比率，开发并简化了一个公式，以便能直接根据81m氪的总计数、99m锝的计数率、99m锝的给予活度以及一个代表每种放射性同位素等量活度预期计数比率的常数来计算给予的活度。该公式允许在进行一组初始实验工作以确定特定伽马相机和准直器系统的常数之后，直接根据图像采集数据进行计算。
