Development of CT radiotherapy machine equipped with micro multileaf collimator

研制了一台具有专用微型多叶准直器的实验性千伏CT放射治疗机，该机器将用于成像以及千伏断层治疗。通过观察水和胸腔模型中的剂量分布，对该系统进行了初步试验。并与来自Co-60源的MeV能量进行了比较。动物实验是用兔子做的。进行了体模实验，从CT测量中获得100，120和135 keV的能谱，并将这些结果与Monte Carlo模拟进行了比较。由实验和模拟光谱计算的水模体中深度剂量百分比（PDD）显示出良好的一致性。135 keV能谱在5、10和15 cm深度的PDD分别为30%、12%和5%。200 keV能量在12 cm深度的水模中的剂量分布比Co-60光子的剂量低近3倍，胸部模中肺区域的剂量分布证明了使用我们的千伏放射治疗机进行断层治疗的可能性。通过动物实验研究了该系统作为千伏级适形断层治疗的详细性能，并在近场特征中获得了长期结果

An experimental kilovoltage CT radiotherapy machine with dedicated micro multileaf collimators was developed, which will be used for imaging as well as for kilo-voltage Tomotherapy. Preliminary trails of this system were investigated by observing the dose distributions in water and thorax phantoms., for the kilo-voltage energies and a comparison was done with the MeV energy from Co-60 source. Animal studies were carried out with rabbits. Phantom experiments were performed to acquire the energy spectra of 100,120 and 135 keV from CT measurements and compared those results with Monte Carlo simulations. The Percentage of Depth Dose (PDD) in the water phantom calculated from the experimental and simulated spectra show good agreement with each other. The PDD of 135 keV spectra at 5,10 and 15 cm depths were 30%,12% and 5%, respectively. Dose distributions in water phantom at a depth of 12 cm for 200 keV energy was almost 3 times lower than that dose of Co-60 photons and dose distributions in the lung region of a thorax phantom demonstrated the possibility of Tomotherapy with our kilo-voltage radiotherapy machine. A detail performance of this system as kilo-voltage conformal Tomotherapy has been investigated with animal studies, and the long term results are obtained in the near feature