Fluke Biomedical 10100AT - Manual (Page 63)

Appendix
Radiological Specifications
B
B-3
Collection Efficiency: The collection efficiency for both continuous intensity and 120 Hz half wave
rectified intensity is theoretically calculated using Boag's equations. An ionization potential of 300V is
used in both cases. An effective plate separation distance of 0.8 cm was determined experimentally
and used to generate the curves below.
Figure B-2. Collection Efficiency of the Model 96020C Ion Chamber
Air Density Correction: To perform air density corrections when using a calibration factor with a
reference temperature of 22°C, multiply the ion current by the following correction factor, F:
(273.15 + T)
F =
295.15 x P
where T is the actual temperature in °C, and P is the pressure expressed as a fraction of a standard
atmosphere (1013 hPa). For chambers with a calibration factor normalized to 20°C, the denominator is
293.15 x P.
B.5 Calibration and Verification
Calibration or calibration verification is performed by comparison of each 96020C ion chamber with a
reference chamber calibrated at either the National Institute of Standards and Technology (NIST) or PTB.
Specifications for all PTB equivalent beam qualities are given in Tables B-1 and B-2 in the energy
correction factor section.
Standard Calibration
The standard calibration is performed at the Fluke Biomedical, Radiation Management Services
equivalent of H60 (NIST defined as 60 kVp, first HVL of 6.0 mm Al, homogeneity coefficient of 94). The
calibration factor is normalized to 22°C and 1013 hPa of atmospheric pressure.
European Calibration Option
This calibration option replaces the standard calibration for units sold in Europe, or when specifically
requested by a customer. This calibration is performed at the Fluke Biomedical, Radiation Management
Services equivalent of DH70 (PTB defined as 70 kVp, first HVL of 6.77 mm Al). The calibration factor is
normalized to 20°C and 1013 hPa of atmospheric pressure.