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Radcal's 10X6-6M ion chamber has excellent energy uniformity and provides accurate dose
measurements for all mammography beam qualities. As a result, this sensor is an excellent solution for
reliable dose measurement for combination modes.
Radcal's AGMS multi-sensors also support accurate dose measurements for a number of combination
mode systems. In particular, the Hologic Dimensions systems are well characterized by the AGMS
sensors. Simply select the W/Al anode filter combination for mammography and accurate total dose
measurements are provided for the 2D+3D Tomographic combination mode.
For all combination mode measurements, ensure that the "End Delay" parameter is set to a sufficiently
large value (8 sec recommended) so that the entire exposure is collected and the measurement doesn't
stop after the first mode.
Measurement Limitations
The Radcal AGMS Series of Multi-Sensors are highly capable instruments that will generally provide a
comprehensive set of measurements throughout a wide range of diagnostic x-ray applications. However, there
are some conditions under which the sensor will provide a more restricted set of measurements. These conditions
are described here:
In instances where filtration exceeds the operating range and/or kV is out of range, the spectral
characteristics provide accurate measurements of Dose and Dose Rate only. Under these circumstances
kV, HVL, and Filtration are not reported and the following warning is displayed:
The AGMS Multi-Sensor operates by measuring the x-ray intensity through several sensing elements
equipped with increasing levels of internal filtration. As the dose decreases below certain levels that are
anode/filter-specific measures of the spectral quantities (kV, HVL, and Filtration) cannot be made reliably.
However, Dose and Dose Rate remain reliable and are reported along with the warning:
Under certain circumstances such as very low kV, excess filtration, and/or large source to sensor distance
there are insufficient x-rays for an accurate measurement or any of the beam properties. Under these
circumstances, no values are reported and the following warning is displayed:
Making Low Dose Measurements with Ion Chambers
When making low dose measurements using an ion chamber (in the range of 10 times the minimum rated
range), it is important to eliminate all sources of noise including noise induced by changing temperatures
of the surroundings and the electronics. Position the ion chamber. Set the threshold to low and wait 3
minutes. Do not touch the cable or digitizer. For changing environments, allow 10 minutes for every 10 C
difference for the sensor/electronics to equilibrate. Grounding the system to eliminate interference may be
warranted.
Low Dose Mode
Insufficient Dose
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