Diode Sensors; Ion Chambers; Ion Chamber Dose Timing Specifications - Radcal Accu Series User Manual

Diode Sensors

DDX10 W, DDX6-W diode sensors:
Energy dependence of sensitivity: +5% to -5% from 40 kVp to 120 kVp at 2.5 mm Al
Filtration dependence of sensitivity: +5% to -10% from 2.5 mm Al to 23 mm Al
Typical zero-level dose fluctuations: 1.5 μR, rms, for a 1-s pulse; 0.5 μR, rms, for a 0.1-s pulse
DDX10 M, DDX6-M diode sensors:
These sensors are calibrated for Mo/Mo. No corrections are applied for other anode/filter combinations.
Energy dependence of sensitivity: ± 5% from 25 kVp to 30 kVp at 30 μm Mo
Energy dependence of sensitivity: ± 5% from 25 kVp to 35 kVp at 30 μm Mo + 2 mm Al
Typical zero-level dose fluctuations: 1.8 μR, rms, for a 1-s pulse; 0.8 μR, rms, for a 0.1-s pulse

Ion chambers

Radcal ion chambers are unsealed. The control unit provides automatic correction for temperature,
pressure and chamber calibration using a memory chip and temperature sensor located in the chamber
stem and pressure measured at the control unit.
Overall ion chamber accuracy is ± 5% at reference conditions.

Ion Chamber Dose Timing Specifications

Measuring time (pulse width)
The Auto-Dose mode provides a pulse width (time) measurement capability when you use either ion
chambers or dose diodes.
For ion chambers, the 10X6-6 and 10X6-6M are recommended. The range of pulse width extends from
10 ms to 9999s. The uncertainty is 4 ms (or 50 ms for the 10X6-1800 only) plus 0.1% of width.
The minimum dose rate for the 6cc Chamber is 650 mR/min or 95 μGy/s.
Minimum total dose for the 6cc Chamber is 0.54 mR or 4.7 μGy.
For other 10X6-series chambers, these minimums are inversely proportional to chamber volume.
When using adapters for 10X5 or 10X9 chambers, time measurements are valid for the -6 and -6M
chambers only.
For time less than 10ms, the dose diode or kV sensors are recommended.
For the DDX6 diodes in Auto Dose the width uncertainty is 1.2 ms plus 0.1% of width over a range from 5
ms to 9999 s. Minimum dose rate is 102 μGy/s or 700 mR/min.
The kV Pulse mode provides pulse width measurement starting even lower at 2 ms and going up to
5.03 s when you use the 40X12-W and 40X9-M sensors. Over this range the uncertainty is 0.2 ms plus
0.1% of the width.
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