中文摘要：

IMRT逆向治疗计划中，速度和精度是IMRT对剂量计算算法的基本和主要要求．直接存储的矩阵有限笔束算法在精度上有其优势，但是计算速度稍慢．基于若干典型算例，比较分析了曲线拟合法和直接数据存储法两种算法在计算精度和速度上的特点，结果显示曲线拟合法速度快，但是精度略低，而直接数据存储法速度慢、精度高．比较结果为IMRT逆向计划过程的剂量计算提供更多算法选择依据，根据系统对算法的要求可以灵活选用这两种算法．

英文摘要：

Speed and precision are primary requirements of dose calculation intensity modulated radiation therapy （IMRT） algorithm in the inverse therapy system. Directly stored as matrix finite size pencil beam algorithm based on Monte Carlo simulation is advantageous in on precision but disadvantageous in speed. Fast finite-size pencil beam （FSPB） algorithm of curve-fitting has been compared with the FSPB direct matrix storing. Both methods depend on Monte Carlo simulation. Based on some typical test example, the characteristics of both algorithms have been compared and analyzed in terms of calculation precision and speed, providing more choice for the dose calculation algorithm in IMRT treatment planning system.