  In the current paper we consider the Helical Cone Beam CT. This scanning
method exposes the patient to large quantities of radiation and results in very
large amounts of data being collected and stored. Both these facts are prime
motivators for the development of an efficient, reduced rate, sampling pattern.
We calculate bounds on the support in the frequency domain of the collected
data and use these to suggest an efficient sampling pattern. A reduction of up
to a factor of 2 in sampling rate is suggested. Indeed, we show that
reconstruction quality is not affected by this reduction of sampling rates.
