Meigooni A S, Meli J A, Nath R
Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Med Phys. 1988 Sep-Oct;15(5):695-701. doi: 10.1118/1.596182.
Dosimetry of brachytherapy sources is critically dependent on precise measurement of the source-detector distance. A solid phantom can be precisely machined and hence distances can be accurately determined. In this work LiF thermoluminescent chips are used for absolute dose rate measurements in solid water, polymethylmethacrylate (PMMA), and polystyrene. These media are examined for their suitability in the dosimetry of 125I by comparing depth doses in each phantom. Measurements and Monte Carlo calculations show that solid water is equivalent to water for the dosimetry of 125I seeds, however, polystyrene and PMMA are not equivalent to water. Also, photon energy spectra for several depths in each phantom material have been calculated and are used to determine average photon energy and mass energy absorption coefficients as a function of depth.
近距离放射治疗源的剂量测定严重依赖于源与探测器距离的精确测量。固体模体可以精确加工，因此距离可以准确确定。在这项工作中，LiF热释光芯片用于在固体水、聚甲基丙烯酸甲酯（PMMA）和聚苯乙烯中进行绝对剂量率测量。通过比较每个模体中的深度剂量，研究了这些介质在¹²⁵I剂量测定中的适用性。测量和蒙特卡罗计算表明，对于¹²⁵I种子的剂量测定，固体水与水等效，然而，聚苯乙烯和PMMA与水不等效。此外，还计算了每种模体材料中几个深度处的光子能谱，并用于确定平均光子能量和质量能量吸收系数随深度的变化。
