248 MI-42-0001 Rev. 19
CT USER INFORMATION: Deterministic Effects
10.4 Deterministic Effects
10.4.1 Radiation Dose Levels
Managing
Radiation Dose
Levels
There is a possibility in normal use that the patient can be exposed to radiation dose levels where
deterministic effects may occur. Operators need to be aware of and manage the possibility of
exposure to high radiation.
10.4.2 Prevailing Radiation Dose
Factors Affecting
Prevailing
Radiation Dose
AIRO selects a protocol based on the data entered for:
• Patient weight
• Body region being scanned
The operator sets the patient height and weight, both of which affect the radiation dose in normal
use. See chapter 6 SCANNING.
After a scout scan is performed, AIRO permits Z-axis tube current modulation as a dose optimization
method for helical scanning modes. For more information, see section 2.7.8 Reducing Risk from X-
ray Dose.
AIRO calculates and displays the kV and mA for the proposed scan.
The Pendant Display shows the CTDI
vol
expressed in units of mGy and DLP in units of mGy.cm, for
head and for body standards. It also displays the phantom type and diameter on which CTDI
vol
values are based. These values are recorded in the scan data.
NOTE: These clinical protocols are proposed by the manufacturer, pre-loaded on the equipment,
displayed prior to scan, and recorded with each scan. They constitute recommendations to be
applied directly so as to allow optimized operation. See the Mobius Imaging LLC Application Guide
for Protocols and Principles (document MI-42-0005).
Deterministic Effect: 1000 mGy CTDI
100 (peripheral)
Number of Scans to Reach
Effect
Typical/maximum head protocol: 120 kV, 326 effective
mAs
10
Typical body protocol: 120 kV, 149 effective mAs 25
Maximum body protocol: 120 kV, 326 effective mAs
(e.g., obese patient)
11
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