K990400 16 April 2008
Radiation Environment Survey
12-9
require that a shielding plan be conducted by a qualified
Physicist or Radiologist and a copy of the shielding plan
be submitted and approved prior to installation of the
system.
• An area radiation survey by a qualified physicist or
Radiologist may then be required within 30 days of initial
clinical use of the system. This survey may be required to be
submitted to the local agency or government body.
• An annual radiation survey may be typically required. This
survey is typically required to be submitted to the local
agency or government body.
• A phantom or patients may be used for system training.
Employees of the facility may not be used for this training.
• The system shall be registered with the local agency or
government body.
Dose and Imaging Performance Information
Conditions of Operation
The dose measurements were made using a PMMA Head Phantom
with a diameter of 16 centimeters and a 10cc ion chamber with an
active length of 10 centimeters.
Procedure Performed:
1. Leveled the Head Phantom and used a light localizer to position
phantom in center of scan, so slice cuts through the center of the
phantom.
2. Performed a Capture view to assess the alignment.
3. Performed a scan.
4. Used image viewer to verify that the center hole is within 5 mm
from the center of the scan in all directions. The central position
is a position where the CTDI values are the maximum.
5. Placed the ionization chamber in the center hole. Inserted acrylic
rods in all other holes.
6. Used typical technique factors.
7. Performed a single scan and read out of the ionization detected
with the chamber X, in coulombs (C).
8. Calculated CTDI using the equation:
CTDI (rad) = Xr x f rad/R x 10(cm) / NST (cm)
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