Tomitani T, Pawelke J, Kanazawa M, Yoshikawa K, Yoshida K, Sato M, Takami A, Koga M, Futami Y, Kitagawa A, Urakabe E, Suda M, Mizuno H, Kanai T, Matsuura H, Shinoda I, Takizawa S
Department of Accelerator Physics and Engineering, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan.
Phys Med Biol. 2003 Apr 7;48(7):875-89. doi: 10.1088/0031-9155/48/7/305.
Heavy ion therapy has two definite advantages: good dose localization and higher biological effect. Range calculation of the heavy ions is an important factor in treatment planning. X-ray CT numbers are used to estimate the heavy ion range by looking up values in a conversion table which relates empirically photon attenuation in tissues to particle stopping power; this is one source of uncertainty in the treatment planning. Use of positron emitting radioactive beams along with a positron emission tomograph or a positron camera gives range information and may be used as a means of checking in heavy ion treatment planning. However, the metabolism of the implanted positron emitters in a living object is unpredictable because the chemical forms of these emitters are unknown and the metabolism is dependent on the organ species and may be influenced by many factors such as blood flow rate and fluid components present. In this paper, the washout rate of 11C activity implanted by injecting energetic 11C beams into thigh muscle of a rear leg of a rabbit is presented. The washout was found to consist of two components, the shorter one was about 4.2 +/- 1.1 min and the longer one ranged from 91 to 124 min. About one third of the implanted beta+ activity can be used for imaging and the rest was washed out of the target area.
良好的剂量定位和更高的生物学效应。重离子射程计算是治疗计划中的一个重要因素。通过在一个将组织中光子衰减与粒子阻止本领经验性关联的转换表中查找数值，利用X射线CT值来估计重离子射程；这是治疗计划中不确定性的一个来源。将正电子发射放射性束与正电子发射断层扫描仪或正电子相机一起使用可提供射程信息，并可用作重离子治疗计划中的一种检查手段。然而，植入的正电子发射体在活体中的代谢是不可预测的，因为这些发射体的化学形式未知，且代谢取决于器官种类，并可能受到许多因素的影响，如血流速度和存在的流体成分。本文给出了通过向兔后腿大腿肌肉注射高能11C束植入的11C活度的洗脱率。发现洗脱由两个部分组成，较短的部分约为4.2±1.1分钟，较长的部分在91至124分钟之间。植入的β+活度约三分之一可用于成像，其余的则从靶区洗脱。
