Often in clinical CT imaging situations, a clinician only requires a small volume of interest (VOI) within a CT slice to be imaged. Unfortunately, due to some fundamental constraints in CT image reconstruction, the entire slice must be irradiated even when a small VOI is all that is clinically required. This produces excess dose for the patient, excess scatter which degrades image quality and increases clinician dose, and may effect patient care because clinicians may limit their use of CT in the interventional setting due to the previous two factors. This paper shows experimental results in which a digital beam attenuator (DBA) is used to modulate the patient dose as a function of view and gantry angle to enhance the SNR in a small VOI relative to the surrounding areas. It was found that the noise was lower by 50% inside the VOI for DBA enabled VOI. This promising result was obtained while providing an incident fluence reduction of 13 times on average for all regions not corresponding to the VOI relative to a non-VOI scan.
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