抄録
The response of five commercially available thimble ionization chambers with various wall materials has been measured for 60Co,4 and 6 MV photon beams. Measurements were mada in air with build up cap of polymethyl methacrylate. To decrease the influence of photon beam fluctuations, a tip to tip calibration procedure was carried out. Responses were also calculated using a cavity theory. Experimental and calculated responses agree within the estimated total uncertainty.
