Section 4 - Alignment & Calibration
4-41
Sample ARRC.TXT (Array Calibration) File
ARRC.TXT Variables Set by… Descriptions
USE = 0 Factory
A variable used by the software to determine
what parameters to use for scatter correction. It
can be set to one of four possible values (0, 1, 2,
or 3) but should
always
be set to
0
.
Q4 = 0.651 1.013 1.461 Factory
These numbers are similar to the Q1, Q2, and
Q3 numbers in ENVIRON.BAT, except these are
used for all array modes. The numbers are
determined by measuring a three-step (thin,
medium, and thick) block phantom at the factory.
Q4_HAT = 0.617 0.980
1.445
Factory Similar to Q4, only the measurements are taken
on the block phantom with extra absorber
material placed on top of it.
T4 = 2.628 Factory Thickness (height in inches) of the block
phantom.
T4_HAT = 7.00 Factory Thickness (height in inches) of the block
phantom with extra absorber.
DELTA0 = 0.493 Factory Thickness of tissue segment in the filter wheel.
T0_N = 6.85 Fact. or
F.S.
Overall height of the phantom (in inches) shipped
with the QDR 4500. (Varies with each phantom.)
HIA_N = 1305.39 Automatic Hi Air,
LOA_N = 1622.56 Automatic Low Air,
HIT_N = 1389.09 Automatic Hi Tissue, and
LOT_N = 1718.52 Automatic Low Tissue attenuations values in "raw A/D"
numbers.
These values are used to determine the
thickness of a patient being scanned in an
AP
array
scan mode. They are updated whenever a
spine
array
scan is added to the QC database
(i.e. the daily array QC scan) or in FSCAL.
ACF = 1.021550 Fact. or
F.S.
Area Correction Factor for AP Spine and Hip
scans
BCF = 1.005450 Fact. or
F.S.
Bone Correction Factor for AP Spine and Hip
scans
SFF = 1.083600
1.095000
Factory Spine Fan Factors
LFF = 0.943000 0.954000 Factory Lateral Fan Factors
HFF = 1.077300 1.120000
1.077300
1.120000
1.077300
1.120000
1.077300
1.120000
Factory Hip Fan Factors
Multiplication factors for BCF & ACF array scans.
These values are the same on all QDR 4500s.
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