Abstract
Multi-leaf collimator (MLC) is a convenient and cost-effective tool as a substitute for alloy blocks for conventional radiation therapy, conformal therapy and intensity modulation radiation therapy (IMRT). It is becoming a standard feature on new accelerator. Before the unit used clinically, the geometric and dosimetry characteristics must be measured and verified to compare with the conventional blocking fields. The object of this dissertation is to investigate the staggered dose distribution smoothing methods, the comprehensive dosimetry characteristics include the collimator, phantom, total scatter factors, peak-scatter factor (PSF), central axis depth dose (PDD or TMR) were evaluated at least for square shaped fields. The abutted region dose leakage at different off-axis distance (OAD) was examined to evaluate the radiation hazard of critical organ at this region. We also develop a technique to examine the stability of leaf speed include the effect of acceleration and deceleration of leaf motion in order to make sure the stability of leaf speed will not affect the intensity profile generated.