8-9
c. Move the position of the slice to the middle of the phantom
on the top-left image as shown below.
32. Right click the image and select HU Statistics from the menu
(also, right click to turn off HU Statistics).
33. Area of ROIs should be at least 40mm
2
but less than 46mm
2
.
Use the Region Tool to define a ROI in the center of each circle
of material implanted within the QA phantom.
34. Record the Hounsfield value of each material. See table below.
35. Call Service, if any of the four measured values exceed the
Lower or Higher limit.
Material
Mean Scan Value
(Hounsfield Units)
Lower
Limit
Upper
Limit
Mean
Air (Black) -1000 -980 -990
Acrylic (Light Gray) 75 125 100
LDPE (Dark Gray) -175 -115 -145
Teflon (White) 1055 1205 1130
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