Schulz R J, Huq M S, Venkataramanan N, Motakabbir K A
Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Med Phys. 1991 Nov-Dec;18(6):1229-33. doi: 10.1118/1.596595.
The temperature-regulated, flexible, water calorimeter developed in the authors' laboratory was shown previously to yield a dose-to-water from 4-MV x rays that is in very close agreement with ionization measurements made in accordance with the AAPM dosimetry protocol. The range of beam energies for this type of comparison has been increased to include 60Co, and 4-, 6- and 25-MV x rays. The grand mean of the ratios of doses obtained from the calorimeter and ionization chamber, the Cal/Ion ratio, for the four beam energies studied is 1.001 +/- 0.001. As no significant trend with beam energy was detected, it is concluded that the calorimeter and ionization chamber yield equally accurate results. Because the calibration of the calorimeter depends solely upon the accuracy with which water temperatures in the range 2-10 degrees C can be measured, and dose is given by the product of the specific heat of water and the temperature change produced by irradiation, the water calorimeter has the potential to place radiation dosimetry on a much firmer foundation than presently exists.
作者实验室研发的温度调节式、灵活的水热剂量仪先前已表明，其得出的4兆伏X射线的水吸收剂量与按照美国医学物理师协会（AAPM）剂量测定协议进行的电离测量结果非常吻合。此类比较的束流能量范围已扩大至包括钴-60以及4兆伏、6兆伏和25兆伏的X射线。在所研究的四种束流能量下，从热剂量仪和电离室获得的剂量比值（即热剂量仪/电离室比值，Cal/Ion比值）的总平均值为1.001±0.001。由于未检测到与束流能量相关的显著趋势，因此得出结论，热剂量仪和电离室产生的结果同样准确。由于热剂量仪的校准仅取决于测量2至10摄氏度范围内水温的准确度，且剂量由水的比热与辐照产生的温度变化的乘积给出，所以水热剂量仪有可能使辐射剂量测定建立在比目前更坚实的基础之上。
