Mourik Jurgen E M, Derks Mark, Te Beek Erik T, Ten Broek Marc R J
Department of Nuclear Medicine, Franciscus Gasthuis & Vlietland Hospital, Kleiweg 500, 3045 PM, Rotterdam, The Netherlands.
Department of Nuclear Medicine, IJsselland Hospital, Capelle aan den IJssel, The Netherlands.
EJNMMI Phys. 2023 Sep 13;10(1):55. doi: 10.1186/s40658-023-00575-2.
Current guidelines of the radioiodine uptake (RAIU) test allow the use of different equipment, isotopes, activity and region-of-interest (ROI). We evaluated presence and extent of these differences in clinical practice and evaluated the effect of some of these variations on RAIU outcomes. Also, gamma camera-specific reference standards were calculated and retrospectively compared with measurements obtained during clinical RAIU tests.
First, questionnaires were sent to Dutch nuclear medicine departments requesting information about equipment usage, isotope, isotope formulation, activity and measurement techniques. Secondly, a neck phantom containing a range of activities in capsule or water-dissolved formulation was scanned. Counts were measured using automatic ROI, square box ROI or all counts in the image. Thirdly, clinical RAIU data were collected during 2015-2018 using three different gamma cameras. Reference standards for each scanner were calculated using regression analysis between reference activity and measured counts. Uptake measurements using this gamma camera-specific reference standard were compared with original measurements.
The survey demonstrated significant differences in isotope, isotope formulation, activity, use of neck phantoms, frequency and duration of reference measurements, distance to collimator, use of background measurements and ROI delineation. The phantom study demonstrated higher counts for the water-dissolved formulation than capsules using both automatic and square box ROI. Also, higher counts were found using a square box ROI than an automatic ROI. The retrospective study showed feasibility of RAIU calculations using camera-specific reference standards and good correlation with the original RAIU measurements.
This study demonstrated considerable technical variation in RAIU measurement in clinical practice. The phantom study demonstrated that these differences could result in differences in count measurements, potentially resulting in different dose calculations for radioactive iodine therapy. Retrospective data suggest that camera-specific reference standards may be used instead of individual reference measurements using separate activity sources, which may thus eliminate some sources of variation.
目前放射性碘摄取（RAIU）试验的指南允许使用不同的设备、同位素、活度和感兴趣区（ROI）。我们评估了临床实践中这些差异的存在情况和程度，并评估了其中一些变化对RAIU结果的影响。此外，计算了γ相机特定的参考标准，并与临床RAIU试验期间获得的测量值进行回顾性比较。
首先，向荷兰核医学科室发送问卷，询问有关设备使用、同位素、同位素制剂、活度和测量技术的信息。其次，对含有一系列胶囊或水溶制剂活度的颈部模型进行扫描。使用自动ROI、方形框ROI或图像中的所有计数来测量计数。第三，在2015年至2018年期间使用三台不同的γ相机收集临床RAIU数据。使用参考活度与测量计数之间的回归分析计算每台扫描仪的参考标准。将使用此γ相机特定参考标准的摄取测量值与原始测量值进行比较。
调查显示，在同位素、同位素制剂、活度、颈部模型的使用、参考测量的频率和持续时间、到准直器的距离、本底测量的使用和ROI划定方面存在显著差异。模型研究表明，使用自动和方形框ROI时，水溶制剂的计数高于胶囊。此外，使用方形框ROI时的计数高于自动ROI。回顾性研究表明，使用相机特定参考标准进行RAIU计算是可行的，并且与原始RAIU测量值具有良好的相关性。
本研究表明临床实践中RAIU测量存在相当大的技术差异。模型研究表明，这些差异可能导致计数测量的差异，可能导致放射性碘治疗的剂量计算不同。回顾性数据表明，可以使用相机特定的参考标准代替使用单独活度源的个体参考测量，从而可能消除一些变异来源。
