Computed Cerenkov luminescence yields for radionuclides used in biology and medicine
Computed Cerenkov luminescence yields for radionuclides used in biology and medicine
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DOI：
10.1088/0031-9155/60/11/4263
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发表时间：
2015-06-07
影响因子：
3.5
通讯作者：
Cherry, Simon R.
中科院分区：
文献类型：
--
作者：
Gill, Ruby K.;Mitchell, Gregory S.;Cherry, Simon R.
切伦科夫发光成像是一种新兴的生物医学成像方式，它利用放射性核素在组织等介电介质中衰变后发出的光学切伦科夫光子。切伦科夫辐射可能允许许多与生物医学相关的放射性核素，包括所有发射正电子的放射性核素，使用灵敏的CCD相机在体内成像。切伦科夫发光还可以提供一种方法，利用靶向放射性示踪剂，在持续的一段时间内将光传递到组织深处。这种光可用于光激活，包括治疗药物的光释放、光动力疗法和光化学内化。评估这些概念的可行性以及为探测切伦科夫辐射而设计的仪器设计的关键是了解组织中不同放射性核素的光产额。这由于光产额与折射率和被询问样品的体积的依赖关系而变得复杂。利用蒙特卡罗模拟，结合Frank-Tamm方程的逐步使用，我们研究了47种不同的放射性核素，表明在400-800 nm的波长范围内，组织中切伦科夫光的产额可以高达几十个光子。讨论了折射率与源体积的依赖关系，给出了计算任意光谱段切伦科夫产额所需的标度因子的表达式。这些数据将对生物医学放射性核素发射的切伦科夫辐射的应用起到广泛的指导作用。
Cerenkov luminescence imaging is an emerging biomedical imaging modality that takes advantage of the optical Cerenkov photons emitted following the decay of radionuclides in dielectric media such as tissue. Cerenkov radiation potentially allows many biomedically-relevant radionuclides, including all positron-emitting radionuclides, to be imaged in vivo using sensitive CCD cameras. Cerenkov luminescence may also provide a means to deliver light deep inside tissue over a sustained period of time using targeted radiotracers. This light could be used for photoactivation, including photorelease of therapeutics, photodynamic therapy and photochemical internalization. Essential to assessing the feasibility of these concepts, and the design of instrumentation designed for detecting Cerenkov radiation, is an understanding of the light yield of different radionuclides in tissue. This is complicated by the dependence of the light yield on refractive index and the volume of the sample being interrogated. Using Monte Carlo simulations, in conjunction with step-wise use of the Frank-Tamm equation, we studied forty-seven different radionuclides and show that Cerenkov light yields in tissue can be as high as a few tens of photons per nuclear decay for a wavelength range of 400-800 nm. The dependency on refractive index and source volume is explored, and an expression for the scaling factor necessary to compute the Cerenkov yield in any arbitrary spectral band is given. This data will be of broad utility in guiding the application of Cerenkov radiation emitted from biomedical radionuclides.