Interlaboratory comparison of two homemade pencil type ionization chambers

Maysa Costa Castro; Natália Fiorini Silva; Linda Viola Ehlin Caldas

doi:10.15392/2319-0612.2024.2329

Authors

Maysa Costa Castro Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear
Natália Fiorini Silva Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear
Linda Viola Ehlin Caldas Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear https://orcid.org/0000-0002-7362-2455

DOI:

https://doi.org/10.15392/2319-0612.2024.2329

Keywords:

pencil type ionization chamber, radiation dosimetry, computed tomography beams

Abstract

Computed tomography (CT) is a diagnostic exam responsible for the highest dose values received by the patients during the procedure. Over the years, this kind of equipment has been improved to ensure that the patients do not receive unnecessary doses. For this reason it is important to keep a quality control program for the CT equipment. To perform the dosimetry in CT beams, the instrument used is usually a pencil type ionization chamber with a sensitive volume length of 10 cm. However, this kind of detector is available with different sensitive volume lengths. The aim of this study was to compare the response of two homemade pencil type ionization chambers with sensitive volume lengths of 10 cm and 30 cm in the laboratories of Instituto de Pesquisas Energéticas e Nucleares (IPEN, Brazil) and National Physical Laboratory (NPL, UK). The characterization tests were performed, and the results obtained are within the international recommended limits. The only difference observed in the response of the two chambers in both laboratories is the fact that the ionization current obtained in all the tests at the IPEN is higher than at the NPL, because of the beam characteristics.

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References

BOONE, J.M. The trouble with CTDI100. Medical Physics, v. 34, p. 1364-1371, 2007. DOI: https://doi.org/10.1118/1.2713240

MCCOLLOUGH, C.H. “Computed tomography technology and dose in the 21st century”. Health Physics, v. 116, p. 157–162, 2019. DOI: https://doi.org/10.1097/HP.0000000000000997

SMITH-BINDMAN, R.; WANG, Y.; CHU, P.; et al., International variation in radiation dose for computed tomography examinations: prospective cohort study. British Medical Journal, v. 364, p. 1-12, 2019. DOI: https://doi.org/10.1136/bmj.k4931

BUSHONG, S.C. Radiologic Science for Technologists: Physics, Biology and Protection. Rio de Janeiro, Elsevier, 2010.

SUZUKI, A.; SUZUKI, M.N. Use of a pencil-shaped ionization chamber for measurement of exposure resulting from a computed tomography scan. Medical Physics. v. 5, p. 536-539, 1978. DOI: https://doi.org/10.1118/1.594445

IAEA, International Atomic Energy Agency. Calibration of Radiation Protection Monitoring Instruments. Safety Report Series IAEA SRS 16, IAEA, Vienna, 2000.

NEVES, L.P.; PERINI, A.P.; CALDAS, L.V.E. Development and characterization of a new cylindrical ionization chamber for dosimetry of 60Co beams. IEEE Transactions on Nuclear Science. v. 60, p. 712-715, 2013. DOI: https://doi.org/10.1109/TNS.2012.2219319

PERINI, A.P.; NEVES, L.P.; FERNÁNDEZ-VAREA, J.M.; BÜERMANN, L.; CALDAS, L.V.E. Evaluation and simulation of a new ionization chamber design for use in computed tomography beams. IEEE Transactions on Nuclear Science. v. 60, p. 768-773, 2013. DOI: https://doi.org/10.1109/TNS.2012.2233752

CASTRO, M.C. Development and Characterization of Special Ionization Chambers for Computed Tomography Beams. Master in Science, Instituto de Pesquisas Energéticas e Nucleares, Universidade de São Paulo (In Portuguese), 2016.

CASTRO, M.C.; SILVA, N.F.; XAVIER, M.; ANDRADE, M.E.A.; KHOURY, H.J.; CALDAS, L.V.E. Development and tests of a 30 cm pencil-type ionization chamber for dosimetry in standard and clinical CT beams. Biomedical Physics & Engineering Express, v. 3(5), p. 1-9, 2017. DOI: https://doi.org/10.1088/2057-1976/aa82e3

IEC, International Electrotechnical Commission. Medical Diagnostic X-ray Equipment. Radiation Conditions for Use in the Determination of Characteristics. 2nd ed. IEC, Genève, (IEC 61267), 2005.

IEC, International Electrotechnical Commission. Medical Electrical Equipment-Dosimeters with Ionization Chambers and/or Semi-Conductor Detectors as used in X-Ray Diagnostic Imaging. Technical Report, IEC, Genéve, (IEC 61674), 1997.