Absorbed dose evaluation to patients undergoing PET–CT and conventional CT examinations

Positron emission tomography (PET) and computerized tomography (CT) are standard imaging tools allowing clinicians to pinpoint the location of cancer within the body before making treatment recommendations. Currently, the combined PET and CT machine (PET-CT) integrated information permits accurate tumor detection and localization for a variety of cancers. In the past, the attenuation correction information needed clinically for PET imaging was provided by a super(68)Ge transmission scan, resulting in prolonging scanning time and poor anatomic image quality in whole-body PET scans. Recently, these drawbacks have been overcome by the introduction of dual-modality which uses CT scan images as attenuation correction maps and provides high-quality anatomic information. However, this whole-body CT protocol in PET-CT is relatively rare in typical diagnostic CT procedures and may potentially produce higher radiation exposure. Our purpose is to characterize the performance of a recently introduced PET-CT scanner and to measure patient doses undergoing one session of PET-CT examination. We also focused on comparing both conventional CT and PET-CT procedures in terms of radiation dose by using the computed tomography dose index (CTDI) protocol. Our goal is to assure a dose as low as possible but still consistent with acceptable image quality in clinical examinations.