Henderson S D, Purdy J A, Gerber R L, Mestman S J
Int J Radiat Oncol Biol Phys. 1987 Jul;13(7):1107-12. doi: 10.1016/0360-3016(87)90051-4.
The present report describes the fabrication technique and the dosimetry aspects of a new compensator system that uses the low melting point allow Lipowitz metal. Compensating ratios (CR, mm of tissue compensated per mm of cerrobend) were determined for various field sizes and depths for 60Co, and X ray energies of 4, 6, 18, and 25 MV. Typical CR for 10 cm X 10 cm field and 10 cm depth were: 60Co, 4 MV, and 6 MV, 1:15; 18 and 25 MV, 1:20. Verification of these CR were performed at 6 MV using polystyrene phantoms. Ionization measurements were made for various field sizes and depths and normalized to central axis full-phantom readings for both compensated and non-compensated fields. Without compensation, percent differences ranged as high as 40% for a tissue deficit of 10 cm. With the compensating filters (CF) in place, this difference was reduced to 2-4%. Overall, the CF system was capable of producing dose uniformity to within +/- 10% for a wide range of depths and field sizes.
本报告描述了一种使用低熔点合金利普维茨金属的新型补偿器系统的制造技术和剂量测定方面的内容。针对60Co以及4、6、18和25 MV的X射线能量，测定了不同射野大小和深度下的补偿比（CR，每毫米铅当量补偿的组织毫米数）。10 cm×10 cm射野和10 cm深度下的典型CR为：60Co、4 MV和6 MV时为1:15；18和25 MV时为1:20。使用聚苯乙烯模体在6 MV下对这些CR进行了验证。对不同射野大小和深度进行了电离测量，并针对补偿野和未补偿野将其归一化为中心轴全模体读数。未进行补偿时，对于10 cm的组织缺损，百分比差异高达40%。使用补偿滤过器（CF）后，该差异降至2 - 4%。总体而言，CF系统能够在很宽的深度和射野大小范围内将剂量均匀性控制在±10%以内。
