This study aimed to verify whether there is whole-body (WB) count loss due to dead time of gamma camera when high amount of 131I is administered to patients. Planar views of a phantom containing 5751 MBq of 131I were acquired at 24-h intervals for 68 d. Eighty-two patients ≤21 y old were given diagnostic activity (74 MBq) followed by therapeutic activity (1110-5772 MBq). WB scans of patients were acquired at 2 h after diagnostic and therapeutic activity administration. Count loss in patients and phantom were compared. In phantom, there was no count loss up to 139 MBq. At maximum activity of 5751 MBq 131I, the loss was 46%. In patients, the average WB count loss was insignificant after the administration of therapeutic activity. Count loss due to dead time in phantom differed significantly from patient results that can probably be explained by the distribution of activity over a large area in vivo.

中文翻译：

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儿童和青少年在治疗后扫描中丢失 131I 计数是否需要校正？体模与患者研究的比较。

本研究旨在验证当对患者施用大量 131I 时，是否存在由于伽马相机的死区时间导致的全身 (WB) 计数损失。包含 5751 MBq 的 131I 的体模的平面视图以 24 小时的间隔获得，持续 68 天。82 名≤ 21 岁的患者进行了诊断活动 (74 MBq)，然后是治疗活动 (1110-5772 MBq)。在诊断和治疗活动给药后 2 小时获得患者的 WB 扫描。比较了患者和体模的计数损失。在幻像中，高达 139 MBq 没有计数损失。在 5751 MBq 131I 的最大活性时，损失为 46%。在患者中，给予治疗活性后平均 WB 计数损失是微不足道的。