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Recombination in Parallel Plate Free-air Ionization Chambers

1961; Wiley; Volume: 34; Issue: 408 Linguagem: Inglês

10.1259/0007-1285-34-408-791

1748-880X

Patricia B. Scott, J R Greening,

Advanced Radiotherapy Techniques

Consideration is given to the choice of the formula which best describes recombination between parallel plates. This formula is modified so that it may be applied to free-air ionization chambers. The modifications entail determining (i) the effective width of a circular cross-section X-ray beam, (ii) the effect of space charge and (iii) the effect of ion spread and distribution. The modified formula is checked experimentally with a small free-air chamber by varying field strength, dose-rate, beam quality and size and shape of the X-ray beam. Good confirmation is obtained.