Mizuno H, Tomitani T, Kanazawa M, Kitagawa A, Pawelke J, Iseki Y, Urakabe E, Suda M, Kawano A, Iritani R, Matsushita S, Inaniwa T, Nishio T, Furukawa S, Ando K, Nakamura Y K, Kanai T, Ishii K
Department of Quantum Science and Energy Engineering, Tohoku University Graduate School of Engineering, Aoba-yama-4, Sendai 980-8579, Japan.
Phys Med Biol. 2003 Aug 7;48(15):2269-81. doi: 10.1088/0031-9155/48/15/302.
Washout of 10C and 11C implanted by radioactive beams in brain and thigh muscle of rabbits was studied. The biological washout effect in a living body is important in the range verification system or three-dimensional volume imaging in heavy ion therapy. Positron emitter beams were implanted in the rabbit and the annihilation gamma-rays were measured by an in situ positron camera which consisted of a pair of scintillation cameras set on either side of the target. The ROI (region of interest) was set as a two-dimensional position distribution and the time-activity curve of the ROI was measured. Experiments were done under two conditions: live and dead. By comparing the two sets of measurement data, it was deduced that there are at least three components in the washout process. Time-activity curves of both brain and thigh muscle were clearly explained by the three-component model analysis. The three components ratios (and washout half-lives) were 35% (2.0 s), 30% (140 s) and 35% (10 191 s) for brain and 30% (10 s), 19% (195 s) and 52% (3175 s) for thigh muscle. The washout effect must be taken into account for the verification of treatment plans by means of positron camera measurements.
研究了用放射性束在兔脑和大腿肌肉中植入的10C和11C的洗脱情况。在重离子治疗的射程验证系统或三维体积成像中，活体中的生物洗脱效应很重要。将正电子发射体束植入兔体内，并用由设置在靶两侧的一对闪烁相机组成的原位正电子相机测量湮灭伽马射线。将感兴趣区域（ROI）设置为二维位置分布，并测量ROI的时间-活度曲线。实验在两种条件下进行：活体和死亡。通过比较两组测量数据，推断出洗脱过程中至少有三个成分。通过三成分模型分析清楚地解释了脑和大腿肌肉的时间-活度曲线。脑的三个成分比例（和洗脱半衰期）分别为35%（2.0秒）、30%（140秒）和35%（10191秒），大腿肌肉的比例为30%（10秒）、19%（195秒）和52%（3175秒）。在通过正电子相机测量验证治疗计划时，必须考虑洗脱效应。
