Diagnostic Reference Level in Computed Tomography : An Evaluation of CT-Protocol Dose Index in a Diagnostic Facility

Recent surveys in large medical centers have found that Computed Tomography (CT) studies now often account for 25% of all examinations and 60 to 70% of the patient dose received from diagnostic radiology (IAEA, 2009). This has created a sense of urgency and the impetus for establishing Diagnostic Reference Level (DRL) and dose reduction strategies. This study presents the assessment and evaluation of patient radiation doses for common CT examinations and derivation of DRLs for common CT examinations. Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) of common CT examinations including: Abdomen, Abdominopelvis, Brain, C-Spine, Chest amongst others were measured using a calibrated GE CT scanner. Data were collected for 402 patients. The mean CTDIv (mGy) and DLP (mGy.cm) for all the protocols were 17.92 & 684.94, 17.09 & 744.56, 51.19 & 852.96, 20.08 & 423.92, 16.8 & 490.07 respectively. When compared with international standards, the great variation in dose distribution was attributed to CT technical parameters, clinical complexity of the patients and inadequate quality control program. There is a dire need to establish local DRL, which are corrective measures that are required in elimination of radiation that does not contribute to overall profile of the patients.