[Intensity-modulation radiotherapy using independent collimator: algorithm study].

To investigate algorithms for independent collimator (IC) to modulate beam intensity distributions. Field-setting sequences were determined for three clinical intensity distributions with two forward algorithms. The delivery order of all fields in the sequences was optimized in order to minimize the overall jaw-moving time. Suppose treatments were performed with Varian 600C, delivery time was calculated. The delivery time was between 5 min to 10 min, It was approximately inversely proportional to machine dose rate, and also related to algorithm, number of intensity levels and metrix element size.