Development of CT radiotherapy machine equipped with micro multileaf collimator

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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