EDUARDO DE LIMA CORREA
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Artigo IPEN-doc 25736 Application of a Tandem system for HVL evaluation in computed tomography2019 - FONTES, LADYJANE P.; CORREA, EDUARDO L.; POTIENS, MARIA da P.A.Computed tomography (CT) is a method of imaging used for the diagnosis and treatment of diseases. Different from the conventional diagnostic radiology equipment, where the test for the determination of the half value layer (HVL) is recommended, in CT equipment due to its geometry, the determination of the HVL is a difficult task and is usually only provided by the manufacturer. The effective energy of a beam is determined by definition, by means of HVL determination. When HVL values are not easily determined, as in the case of CT, it is possible to evaluate the effective energy of the beam through a system consisting of the use of different energy dependent dosimeters, where the ratio between the calibration curve responses in energy can provide the effective energy of the beam (Tandem system). The system used in this work for the evaluation of HVL in computed tomography is composed of groups formed by an ionization chamber of the pencil-type and cylindrical absorber layers of aluminum and Polymethyl methacrylate (PMMA).Artigo IPEN-doc 25107 Influence of the vials radioactive residue in Nuclear Medicine procedure applied to a new “in situ” activimeter calibration methodology2019 - KUAHARA, L.T.; CORREA, E.L.; CARNEIRO, R.C.G.; BEZERRA, R.R.L.; POTIENS, M.P.A.In this study we present a new “in situ” calibration methodology establishment for activimeters – i.e., this equipment calibration can be made at the hospital and/or the nuclear medicine service (NMS) – and also the importance of considering vials radioactive residue when generating the calibration coefficient in terms of activity (NA). For the calibration, two methods are presented here: in the first, 99mTc sample activity (AC) is measured in the NMS. Then it is sent to the Instruments Calibration Laboratory (LCI/IPEN) where the reference activity (AR) is obtained under controlled conditions in a reference vial. After geometry and residue corrections, NA is calculated. In the second method, AR is obtained at the LCI, then 99mTc sample is sent to the hospital/NMS, where AC is measured and NA calculated. Calibration methodologies were applied to three NMS and to four equipment belonging to the radiopharmaceutical production facility (CR) at the Nuclear and Energy Research Institute (IPEN). Both methodologies were tested with and without residual activity corrections under controlled conditions. Variations of up to 4% were obtained.