Operating instructions

Radiation Therapy
521
Additional Important Information
HU values
The HU values are of crucial importance for the therapy
planning systems of radiation therapists!
• With huge objects, the CT value is independent of
the kernel. With smaller objects, edge effects pro-
duced by the kernel influence the HU values as well
as the scanning. Feed and collimation do not have
any influence.
• An extended FoV of 800 mm means that only 500
mm are scanned, the rest will be interpolated.
• The effect on the HU values of having carbon plate
tagged additionally to the patient table should be
negligible and not measurable.
• CARE Dose 4D does not have any effect on the HU
values.
• HU values and the conversion of the electron densi-
ties depend on the applied spectrum, e.g. kV, prefil-
tration.
• HU values depend on the use of the PFO filter