Radiation dosimetry, dose calculation algorithms, Monte Carlo simulation techniques; Intensity-modulated radiation therapy (IMRT), treatment optimization, beam delivery, dose verification; Modulated electron radiation therapy (MERT), treatment planning, beam delivery and dose verification; Real-time, image-guided robotic radiosurgery/therapy, plan optimization and beam delivery; Laser-accelerated proton beams for radiotherapy, particle-in-cell (PIC) simulations, target design, Particle selection and collimation system, proton dose calculation, plan optimization and beam delivery.