Using SMT phototransistors for computed tomography dosimetry

Authors

  • C. M. S. de Magalhães Departamento de Energia Nuclear, Universidade Federal de Pernambuco
  • J. O. da Silva Departamento de Energia Nuclear, Universidade Federal de Pernambuco
  • J. Antônio Filho Departamento de Energia Nuclear, Universidade Federal de Pernambuco
  • L. A. P. dos Santos Centro Regional de Ciências Energéticas e Nucleares, Comissão Nacional de Energia Nuclear

Keywords:

phototransistors, dosimetry, computed tomography.

Abstract

A dosimetry system using commercially available SMT (Surface-Mount Technology) phototransistors is evaluated for dose measurements in X-ray computed tomography. First, the phototransistors were characterized at the laboratory using a Pantak X-ray in the standard radiation quality RQR9 from IEC61267. The following tests were realized: energy dependence, response with dose rate and repetitivity. The phototransistors yielded a real-time readout and a 6430 Sub-femto-ampermeter Keithley® was used to obtain their electrical current. This methodology allowed the correlating of their results with a standard ionisation chamber, a NE2571 ionization chamber coupled to a NE2670 electrometer that measured the applied dose at the detector position. After the characterization of the phototransistors, freein-air and in head phantom dose measurements were carried out with the dosimetry system at the Hospital. Phototransistors were used to determine the dose profile measurements along the axis of rotation undergoing CT head examination. A Flip-Flop electrometer was used to obtain these measurements. The results indicated that the current values were reliable when compared with the results of doses of CT ionization chamber under the same conditions. The loss of radiation sensitivity, postirradiation, with time is not significant and the SMT phototransistor brings some features to CT dosimetry including high sensitivity, small size, real-time measurements and linearity.

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How to Cite

de Magalhães, C. M. S., da Silva, J. O., Antônio Filho, J., & dos Santos, L. A. P. (2011). Using SMT phototransistors for computed tomography dosimetry. Scientia Plena, 3(7). Retrieved from https://www.scientiaplena.org.br/sp/article/view/654

Issue

Vol. 3 No. 7 (2007): November/Novembro 2007

Section

Articles

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