Department of Medical Physics, Tarbiat Modares University, Tehran, Iran.
Med Phys. 2011 Oct;38(10):5509-21. doi: 10.1118/1.3637493.
Size, shape, and the position of paired organs are different in abdomen. However, the counterpart organs are conventionally treated jointly together in internal dosimetry. This study was performed to quantify the difference of specific absorbed fraction of organs in considering paired organs jointly like single organs or as two separate organs.
Zubal phantom and GATE Monte Carlo package were used to calculate the SAF for the self-absorption and cross-irradiation of the lungs, kidneys, adrenal glands (paired organs), liver, spleen, stomach, and pancreas (single organs). The activity was assumed uniformly distributed in the organs, and simulation was performed for monoenergetic photons of 10, 50, 100, 500, 1000 keV and mono-energetic electrons of 350, 500, 690, 935, 1200 keV.
The results demonstrated that self-absorption of left and right counterpart organs may be different depending upon the differences in their masses. The cross-irradiations between left-to-right and right-to-left counterpart organs are always equal irrespective of difference in their masses. Cross-irradiation from the left and right counterpart organs to other organs are different (4-24 times in Zubal phantom) depending on the photon energy and organs. The irradiation from a single source organ to the left and right counterpart paired organs is always different irrespective of activity concentration.
Left and right counterpart organs always receive different absorbed doses from target organs and deliver different absorbed doses to target organs. Therefore, in application of radiopharmaceuticals in which the dose to the organs plays a role, counterpart organs should be treated separately as two separate organs.© 2011 American Association of Physicists in Medicine.
腹部的器官大小、形状和位置都不同。然而，在内部剂量学中，传统上通常将配对器官视为一个整体进行联合处理。本研究旨在量化在考虑配对器官时，器官的特定吸收分数（SAF）的差异，将其视为单个器官或两个单独的器官。
使用 Zubal 体模和 GATE 蒙特卡罗软件包计算了肺、肾、肾上腺（配对器官）、肝、脾、胃和胰（单个器官）的自吸收和交叉照射 SAF。假设器官内的活性均匀分布，并对 10、50、100、500、1000keV 的单能光子和 350、500、690、935、1200keV 的单能电子进行了模拟。
结果表明，由于质量的差异，左、右配对器官的自吸收可能不同。左、右配对器官之间的交叉照射总是相等的，与它们的质量差异无关。来自左、右配对器官的交叉照射到其他器官的情况因光子能量和器官而异（在 Zubal 体模中为 4-24 倍）。来自单个源器官的照射到左、右配对器官的情况始终不同，与放射性药物的活性浓度无关。
左、右配对器官总是从靶器官接收到不同的吸收剂量，并向靶器官提供不同的吸收剂量。因此，在放射性药物剂量对器官有影响的应用中，应将配对器官视为两个单独的器官分别进行处理。
