Mellenberg D E, Tilbury R S, Hogstrom K R
Department of Radiation Physics, University of Texas, M.D. Anderson Hospital and Tumor Institute, Houston 77030.
Int J Rad Appl Instrum B. 1988;15(6):631-5. doi: 10.1016/0883-2897(88)90054-2.
When radiotherapy patients are irradiated with fast neutron beams (energies greater than 20 MeV), positron emitting radionuclides (15O, 13N, 11C) are created in their tissues. Capillary blood flow can be determined in the irradiated tissue by measuring the washout of the 15O. The chemical form of these positron emitting nuclides is important when assumptions about their transport in the development of a blood flow model are being made. In the present work, normal mouse spleen tissue was used as a model system for these studies. The mouse spleen was activated by whole mouse irradiation using the M.D. Anderson Hospital neutron beam produced by 42 MeV protons impinging on a beryllium target. Results of cellular studies and large molecule precipitation measurements (1) show that at least 65% of 15O created in situ in mouse spleen is capable of being transported out of the spleen by the blood supply, (2) suggest that 13N may be 100% biologically mobile, and (3) indicate that 11C appears to be evenly divided between a population associated with small biologically mobile molecules and a population associated with larger, biologically trapped or immobile molecules.
当放射治疗患者接受快中子束（能量大于20兆电子伏）照射时，其组织中会产生发射正电子的放射性核素（¹⁵O、¹³N、¹¹C）。通过测量¹⁵O的清除情况，可以确定受照射组织中的毛细血管血流量。在建立血流模型时，对这些发射正电子核素的化学形式进行假设时，其化学形式很重要。在本研究中，正常小鼠脾脏组织被用作这些研究的模型系统。使用由42兆电子伏质子撞击铍靶产生的MD安德森医院中子束对小鼠进行全身照射，从而激活小鼠脾脏。细胞研究和大分子沉淀测量结果表明：（1）小鼠脾脏原位产生的¹⁵O中至少65%能够通过血液供应运出脾脏；（2）表明¹³N可能100%具有生物活性；（3）表明¹¹C似乎在与小的具有生物活性的分子相关的群体和与大的、生物捕获或无活性的分子相关的群体之间平均分配。
