Mitra S, Wolff J E, Garrett R, Peters C W
Growth Physiology Group, AgResearch, Ruakura, Hamilton, New Zealand.
Phys Med Biol. 1995 Jun;40(6):1045-55. doi: 10.1088/0031-9155/40/6/006.
A small and compact sealed tube neutron generator with an integral alpha particle detector has been used for applying the associated particle technique for prompt-gamma 14 MeV neutron activation analysis of total body carbon (TBC), total body nitrogen (TBN) and total body oxygen (TBO). Ground sheep meat samples in the weight range 20-40 kg and of varying composition have been scanned using two 12.5 cm diameter x 10 cm Nal(Tl) crystals for gamma-ray detection. The content of protein, fat and water was calculated from their fractional content of C, N and O using a four-compartment model of body composition, which included minerals. The precision for measuring TBC, TBN and TBO has been obtained from the mean count rates of ten repeat irradiations of the same sample. The accuracy has been confirmed by comparison against chemical analysis. The reproducibilities for measuring TBN have been found to be comparable to those obtained when the same samples were analysed using prompt-gamma thermal-neutron activation analysis in an existing body composition facility. Based on the results obtained, we conclude that an instrument comprising the neutron generator and four 15 cm x 15 cm x 45 cm NaI(Tl) gamma ray detectors can be assembled to determine, in vivo, protein, fat and water in an approximately 41 kg sample with precisions of 4.4%, 5.0% and 2.1% (CV) respectively within a 15 min scan. The radiation dose equivalent delivered due to neutrons would be approximately 0.03 mSv.
一种带有内置α粒子探测器的小型紧凑型密封管中子发生器已被用于应用关联粒子技术，对全身碳（TBC）、全身氮（TBN）和全身氧（TBO）进行瞬发γ射线14 MeV中子活化分析。使用两个直径12.5 cm×10 cm的碘化钠（铊）晶体对重量范围为20 - 40 kg且成分各异的地面羊肉样本进行扫描，以检测γ射线。蛋白质、脂肪和水的含量是根据它们在包含矿物质的身体成分四室模型中碳、氮和氧的分数含量计算得出的。通过对同一样本进行十次重复辐照的平均计数率，获得了测量TBC、TBN和TBO的精度。通过与化学分析进行比较，证实了测量的准确性。已发现测量TBN的重现性与在现有身体成分检测设备中使用瞬发γ热中子活化分析对相同样本进行分析时所获得的重现性相当。基于所获得的结果，我们得出结论，可组装一台由中子发生器和四个15 cm×15 cm×45 cm碘化钠（铊）γ射线探测器组成的仪器，在15分钟扫描内，以分别为4.4%、5.0%和2.1%（CV）的精度在体内测定约41 kg样本中的蛋白质、脂肪和水。由于中子产生的辐射剂量当量约为0.03 mSv。
