The 0.02 cm3 soft X-ray chamber type 23342 is the standard ionization chamber for dose measurements in superficial radiation therapy. The 0.20 cm3 chamber type 23344 with its bigger sensitive volume is used for similar purposes, where a higher response is required. The usual calibration of both chambers is done at 15 kV to 70 kV. The chambers have a very flat energy response in the range from 10 kV to 100 kV. The 0.0053 cm3 soft X-ray chamber type 34013 has an extremely small sensitive volume and makes it possible to measure therapeutic X-ray beams with very small field sizes or with steep fluence gradients. The calibration is typically done at 15 to 50 kV. The energy response within this range is ± 2 %
