i-CAT FLX V Series, Technical Manual, Page: 105 / 122

C-11
Radiation Information
032-0328-EN Rev K
Dose and Sensitivity Profile
The dose profile for the 16 and 23 cm scans were performed using a 0.3 mm solid state CT probe.
Measurements were made at 0.5 and 1 cm intervals across the profile of the beam using an 8.9
second scan. The results were normalized to the maximum value and plotted versus detector
position.
Patient Dose
CTDI
w
- Weighted Computed Tomography Dose Index
- Developed to establish the dose in a
phantom to a voxel of tissue from contributions of dose from all slices in a multi-slice protocol.
This measurement uses a 100 mm ionization chamber and approximates the dose from the
primary beam and slices adjacent in a single scan (single slice). For the measurement to be valid,
the X-ray width should be much less than 100 mm. This measure takes into account the sum of
1/3 of the phantom central dose and 2/3 of the peripheral dose. CTDI
w
was not intended to be
used for CBCT. As such, this should be considered an approximate value only. Data was collected
with a Radcal Model 3036 electrometer connected to a 3 cc CT chamber in a 16 cm AAPM head
phantom.
Sensitivity profile
Dose profile