Establishing Diagnostic Reference Level for Computed Tomography Examination in Madagascar

Abstract

The doses received by the patient during Computed Tomography (CT) examination are relatively significant compared with the doses received by patients undergoing classic X-ray examinations. Owing to this, each country should adopt a consistent policy to optimize the doses delivered to the patient during CT examination. One of the available options for the dose optimization is the implementation of the Diagnostic Reference Levels (DRLs) to evaluate thedose delivered to the patient and to guide the operators for the choice of parameters during CT examinations. Actually, Madagascar hasn’t got yet his own DRLs, so that the International Atomic Energy Agency (IAEA) or other international existing DRLs are used to fill this gap. The present study was performed to analyze the feasibility of setting (DRLs) atnational level. The study is a part of an IAEA Project entitled “Strengthening Technical Capabilities for Patient and Occupational Radiation Protection in Member States”, RAF9053. For this purpose, three public and private hospitals using computed tomography were selected. The patient dose assessment was performed by determining the Computed Tomography Dose Index (CTDI), Multiple Scan Average Dose (MSAD), Dose Length Product (DLP) and Effective dose (E) for an adult chest and skull CT examination. Pencil ionization chamber was used, having an active length of 100 mm, connected with an electrometer (RAD-CHECK). The system was calibrated through the Secondary Standard Dosimetry Laboratory of Madagascar (SSDL-Madagascar) before the measurements campaign. To simulate the patient presence, two types of Polymethylmethacrylate (PMMA) phantoms were used. The first, having 32 cm diameter was used to replace an adult body patient, and the second phantom, having 16 cm diameter simulate the head of an adult patient. The results were compared with the International Diagnostic Reference Level which is chosen for this study. It has beenestablished that the obtained values are similar to the existing DRLs. Measurements performed during this study can be useful for the patient dose optimization and considered as the first and main step for the National Diagnostic Reference Level setting for Computed Tomography in Madagascar.