24 MI-42-0001 Rev. 19
SAFETY: Radiation Safety
Dose Notifications
and Alerts for
Modulated Scans
Because AIRO estimates the CTDI
vol
or DLP dose for the next scan and tracks the CTDI
vol
or DLP
totals for a patient’s study, dose Notifications and Alerts can occur when a scan’s standard, fixed mA
estimate:
• Is greater than the protocol’s dose check notification value.
• Pushes the estimated total dosage of the study over the maximum global CTDI
vol
or DLP
settings.
When the system sees these potential dosage issues, it displays and logs the Notification or Alert.
However, the dose of the actual scan may not exceed the Notification and Alert limits when a scan
sequence includes the following options:
1. Scout scan
2. Optimized the field of view
3. Modulated Tube Current option (Helical scans only)
As a result, AIRO includes the actual scan data in the record of the Notification or Alert. This
indicates that the estimated dose exceeded system settings, but that the optional dose reduction
features allowed the scan or study to fall within the set limits.
For more information on:
• Using Scout scans, see 6.8.10 Selecting 2D Scout Scan View on page 101.
• Optimizing field of view, see 6.8.15 Selecting 3D Scan Region on page 110.
• Selecting Modulated Tube Current, see 6.8.16 Selecting a Constant or Modulated Scan on
page 114.
• Viewing and exporting Dose Reports, see 7.2.10 Option: Dose Check Report on page 149.
2.7.4 Profile of Stray Radiation
Technique Factors Stray radiation was measured with a PMMA body dosimetry phantom (32 cm diameter)
placed at
isocenter on the patient table, as specified in IEC standard 60601-2-44:203.13.1 (2016). A RaySafe
X2 Solid State Sensor was used to measure exposures. Measurements on the horizontal plane were
made at isocenter height, and on the vertical plane at the centerline of the table, at 50 cm intervals.
Single axial scans were made at 120 kV, 25 mA, 2 sec (50 mAs), and exposure readings were
recalculated to 192 mAs. Measurements were collected from three individual AIRO systems and the
tables below show the mean of those results.
NOTE: The choice of an ion-chamber survey meter vs. a solid state detector, as well as subtle
changes in orientation and positioning of the survey instrument can result in deviations from the
observed values by as much as 50%.
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