Department of Nuclear Medicine and PET Center, Tri-Service General Hospital, 325, Cheng-Kung Road, Sec. 2, Taipei, Taiwan.
Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, R.O.C, Taiwan.
J Radiat Res. 2020 Sep 8;61(5):697-704. doi: 10.1093/jrr/rraa046.
To investigate the possible influence of head rotation on the results of salivary gland scintigraphy, a phantom study was designed to simulate clinical salivary gland scintigraphy. The quantitative accuracy of regional activity counts was compared for two data acquisition methods involving head rotation: (i) an anterior planar projection-only (ANT) method and (ii) a geometric mean (GM) method using both the anterior and posterior planar projections. The roles and limitations of the GM and ANT methods when used at different head rotation angles were examined. Parallel planar projections of a head phantom with four salivary gland simulators, containing 3.7 MBq 99mTc-sodium pertechnetate, at various rotational settings were acquired using a dual-head gamma camera. The difference between the standard activity counts (no phantom rotation) and the activity counts affected by the phantom rotation was calculated and defined as the rotational bias that decreased the accuracy of activity quantification. For small-angle rotation (≤10°), use of the GM method decreased the bias for all salivary gland simulators. In contrast, the bias of large-angle rotation (>10°) between four salivary gland simulators became conspicuous and complex in both methods. This bias may reflect different attenuation effects caused by displacement of the structures. Our data suggest that the GM method can be used when the head rotation angle is small (≤10°); however, when the head rotation angle is >10°, the non-negligible influence of head rotation should be considered during image acquisition.
为了研究头部旋转对唾液腺闪烁显像结果的可能影响，我们设计了一个模拟临床唾液腺闪烁显像的体模研究。我们比较了两种涉及头部旋转的采集方法（即仅前位平面采集（ANT）和使用前位和后位平面采集的几何平均值（GM）方法）的区域活性计数定量准确性。研究了 GM 和 ANT 方法在不同头部旋转角度下的作用和局限性。使用双探头伽玛相机，对包含 3.7MBq 99mTc-高锝酸钠的四个唾液腺模拟体的头模进行了平行平面采集，模拟体具有不同的旋转设置。计算并定义了标准活性计数（无体模旋转）和受体模旋转影响的活性计数之间的差异，将其定义为降低定量活性准确性的旋转偏差。对于小角度旋转（≤10°），GM 方法的使用降低了所有唾液腺模拟体的偏差。相比之下，两种方法中，四个唾液腺模拟体之间的大角度旋转（>10°）的偏差变得明显且复杂。这种偏差可能反映了结构位移引起的不同衰减效应。我们的数据表明，当头部旋转角度较小时（≤10°），可以使用 GM 方法；但是，当头部旋转角度>10°时，在图像采集过程中应考虑到头部旋转的不可忽略的影响。
