5. Measurements with the Barracuda System
Dental and Panoramic Dental
2012-10/4.3A
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Barracuda & QABrowser Reference Manual
since the display is continuously updated.
11. Stop the panoramic dental unit. The RTI logo
flashes and the last kVp value is displayed. As
complementary information the estimated total
filtration is measured as well as the scan time.
The figure shows the RTD after a complete
scan.
The waveform is also automatically stored after the delay time in the beginning of the
scan or acquired when Hold is activated during the scan.
5.7.4 HVL, Total Filtration, and Quick-HVL
It is not unusual that the total filtration is as low as 2.0 mm Al on an dental unit,
compared to 2.5 to 3.5 mm on an normal radiography unit. The method that the MPD
uses to estimate the total filtration in the range of 1.2 to 38 mm has an absolute
inaccuracy in order of ±0.3 mm, but is very straightforward to find an "unknown" filter in
the beam. You can always use the standard HVL method adding extra filter in the
beam. In that case, use the same procedure as described in the section for the normal
radiography measurement.
CT5.8
This topic will describe how to
measure kVp, dose (CTDI), and
exposure time (scan time) on a
CT. To measure CT dose and
CTDI a Barracuda with an
electrometer module with bias,
a CT ion chamber, and a CT
phantom are required.
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