TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada. Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, V6T 1Z3, Canada.
Phys Med Biol. 2018 Sep 28;63(19):195009. doi: 10.1088/1361-6560/aadf7b.
Gas target systems have been used for decades on cyclotrons to produce radionuclides for medical imaging. However, the activity recovered from such targets is often lower than its theoretically predicted value. Past research has suggested that nuclide interactions with the walls of the target body may play a key role in the loss of recoverable radionuclide activity. Here, we consider gas targets and modify the standard radionuclide production equation by adding a loss term representing radionuclides depositing on the walls of the target. We derive the form of the deposition term based on a simple adsorption model which is then linearized by solving for leading order terms. The resulting production equation uses one fitting parameter to give an estimate of the recoverable activity produced in a target system, taking adsorption into account. The model is then fit to six data series, taken in-house and reported in the literature and a parity plot compares model predictions to experimental data. The model is able to better track the data than any previous models, and points towards a phenomenological understanding of adsorption in target systems.
气体靶系统在回旋加速器上已经使用了几十年，用于生产用于医学成像的放射性核素。然而，从这种靶中回收的放射性核素的活度通常低于其理论预测值。过去的研究表明，核素与靶体壁的相互作用可能在可回收放射性核素活度的损失中起关键作用。在这里，我们考虑气体靶，并通过添加代表放射性核素在靶壁上沉积的损失项来修改标准的放射性核素生产方程。我们根据一个简单的吸附模型推导出沉积项的形式，然后通过求解主要项来线性化。所得的生产方程使用一个拟合参数来估计在考虑吸附的情况下靶系统中产生的可回收活度。然后，该模型拟合了六个数据系列，包括内部和文献中报道的数据，并通过奇偶校验图比较了模型预测与实验数据。与任何以前的模型相比，该模型能够更好地跟踪数据，并指向对靶系统中吸附的现象学理解。
