Rousseau Julia, Boudou Caroline, Estève François, Elleaume Hélène
INSERM U647, Grenoble, France.
Int J Radiat Oncol Biol Phys. 2007 Jul 1;68(3):943-51. doi: 10.1016/j.ijrobp.2007.01.065.
To evaluate direct intracerebral and intratumoral iodine delivery as means to improve iodine distribution for synchrotron stereotactic radiotherapy (SSR) and to evaluate the corresponding X-ray dose distribution.
Healthy rats and F98 glioma-bearing rats received an iodinated contrast agent (iopamidol) intracerebrally either by bolus injection (5 microL over approximately 1 min) or by convection-enhanced delivery (infusion volumes of 5, 10, and 20 microL at a rate of 0.5 microL/min). We used synchrotron computed tomography (CT) to determine the iodine distribution after completion of infusion and a Monte Carlo code to compute the resulting radiation dose in SSR.
Post-infusion CT imaging revealed high iodine concentrations in the perfused area with both injection methods. The iodine concentration remained elevated, with an exponential decay time constant of approximately 50 min, well suited for SSR treatment. Convection-enhanced delivery was shown to provide more uniform and controlled volumes of distribution than bolus injection and was chosen to evaluate the corresponding X-ray dose distribution. Sharp dose gradients around the target and excellent sparing of the contralateral brain were achievable with low iodine concentrations in the surrounding healthy brain tissues and blood vessels.
Convection-enhanced delivery is an effective method to deliver high iodine concentrations and could improve the outcome of iodine-enhanced SSR.
评估直接向脑内和肿瘤内递送碘作为改善同步加速器立体定向放射治疗（SSR）碘分布的手段，并评估相应的X射线剂量分布。
健康大鼠和荷F98胶质瘤大鼠通过推注注射（约1分钟内注射5微升）或对流增强递送（以0.5微升/分钟的速率输注5、10和20微升）向脑内注射碘化造影剂（碘帕醇）。输注完成后，我们使用同步加速器计算机断层扫描（CT）确定碘分布，并使用蒙特卡罗代码计算SSR中产生的辐射剂量。
两种注射方法在灌注区域输注后CT成像均显示高碘浓度。碘浓度持续升高，指数衰减时间常数约为50分钟，非常适合SSR治疗。与推注注射相比，对流增强递送显示出提供更均匀和可控的分布体积，并被选择用于评估相应的X射线剂量分布。在周围健康脑组织和血管中碘浓度较低的情况下，可在靶区周围实现陡峭的剂量梯度，并对侧脑得到极好的保护。
对流增强递送是递送高碘浓度的有效方法，可改善碘增强SSR的效果。
