2013 International Nuclear Atlantic Conference - INAC 2013 Recife, PE, Brazil, November 24-29, 2013 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-05-2 BIPOLAR JUNCTION TRANSISTOR AS A DETECTOR FOR MEASURING IN DIAGNOSTIC X-RAY BEAMS Francisco A. Cavalcanti1,2, David S. Monte1,2, Aline N. Alves1,2, Fábio R. Barros2, Marcus A. P. Santos2, and Luiz A. P. Santos1,2 1 Departamento de Energia Nuclear Universidade Federal de Pernambuco Av. Prof. Luiz Freire, 1000 50740-540 Recife, PE
[email protected] 2 Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE / CNEN) Av. Prof. Luiz Freire, 1 50740-540 Recife, PE
[email protected] ABSTRACT Photodiode and phototransistor are the most frequently used devices for measuring ionizing radiation in medical applications. The cited devices have the operating principle well known, however the bipolar junction transistor (BJT) is not a typical device used as a detector for measuring some physical quantities for diagnostic radiation. In fact, a photodiode, for example, has an area about 10 mm square and a BJT has an area which can be more than 10 thousands times smaller. The purpose of this paper is to bring a new technique to estimate some physical quantities or parameters in diagnostic radiation; for example, peak kilovoltage (kVp), deep dose measurements. The methodology for each type of evaluation depends on the energy range of the radiation and the physical quantity or parameter to be measured. Actually, some characteristics of the incident radiation under the device can be correlated with the readout signal, which is a function of the electrical currents in the electrodes of the BJT: Collector, Base and Emitter.