Nath R, Meigooni A S, Meli J A
Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Med Phys. 1990 Nov-Dec;17(6):1032-40. doi: 10.1118/1.596584.
Dose rates along the transverse axes of 125I model 6702, 125I model 6711 and 192Ir 0.2-mm steel sources for interstitial brachytherapy have been measured in a solid-water phantom for distances up to 10 cm using LiF thermoluminescent dosimeters (TLDs). Specific dose rate constants, the dose rates in water per unit source strength 1 cm along the perpendicular bisector of the source, are determined to be 0.90 +/- 0.03, 0.85 +/- 0.03, and 1.09 +/- 0.03 cGy h-1 U-1 for 125I model 6702, 125I model 6711 and 192Ir 0.2-mm steel sources, respectively (1 U = unit of air kerma strength = 1 microGy m2 h-1 = 1 cGy cm2 h-1). In older and obsolete units of source strength (i.e., mCi apparent), these are 1.14 +/- 0.03, 1.08 +/- 0.03, and 4.59 +/- 0.15 cGy h-1 mCi-1 (apparent). Currently accepted values of specific dose rate constant for 125I sources are up to 20% higher than our measured values which are in good agreement with the results of our Monte Carlo simulations. But for 192Ir there is good agreement between our measured value of the specific dose rate constant and currently accepted values. The radial dose function for 125I model 6702 is found to be consistently larger than that for 125I model 6711, with an increasing difference as the distance from the source increases. Our measured values for the radial dose function for 125I sources are in good agreement with the results of our Monte Carlo simulation as well as the measured values of Schell et al. [Int. J. Radiat. Oncol. Biol. Phys. 13, 795-799 (1987)] for model 6702 and Ling et al.(ABSTRACT TRUNCATED AT 250 WORDS)
使用氟化锂热释光剂量计（TLD），在固体水模体中测量了用于组织间近距离治疗的125I型号6702、125I型号6711和192Ir 0.2毫米钢源沿横向轴在距离达10厘米时的剂量率。比剂量率常数，即沿源的垂直平分线在1厘米处每单位源强在水中的剂量率，对于125I型号6702、125I型号6711和192Ir 0.2毫米钢源分别确定为0.90±0.03、0.85±0.03和1.09±0.03 cGy h-1 U-1（1 U =空气比释动能强度单位 = 1微戈瑞·米2 h-1 = 1厘戈瑞·厘米2 h-1）。在旧的和过时的源强单位（即表观毫居里）中，这些值分别为1.14±0.03、1.08±0.03和4.59±0.15 cGy h-1 mCi-1（表观）。目前公认的125I源的比剂量率常数的值比我们测量的值高20%，我们的测量值与蒙特卡罗模拟结果吻合良好。但对于192Ir，我们测量的比剂量率常数的值与目前公认的值吻合良好。发现125I型号6702的径向剂量函数始终大于125I型号6711的径向剂量函数，且随着与源距离的增加差异增大。我们测量的125I源径向剂量函数的值与蒙特卡罗模拟结果以及Schell等人[《国际放射肿瘤学、生物学、物理学杂志》13, 795 - 799 (1987)]对型号6702的测量值以及Ling等人的测量值吻合良好。（摘要截短于250字）
