MEASUREMENT OF PERCENTAGE DEPTH-DOSE AND LATERAL BEAM PROFILE FOR KILOVOLTAGE X-RAY THERAPY BEAMS

In this work, nine commonly used dosimetry detectors have been investi gated to determine suitable relative dosimeters for kilovoltage x-ray beams. By comparison with the Monte Carlo calculated data, it was dete rmined that for the detectors studied the PTW N23342, Markus and NACP parallel-plate chambers are more suitable for the measurement of perce ntage depth dose (PDD) data for this beam quality range with an uncert ainty of about 3%. A diode detector may be used to measure the PDD for the 100 kVp beam, but it is not suitable for higher energies (300 kVp ). The Capintec parallel-plate chamber may be adequate for medium-ener gy photons, but it has a slightly higher uncertainty for low-energy x- rays (100 kVp). For the measurement of beam profiles, diode and film y ield incorrect profile tails, which can be corrected using the RK ioni zation chamber.