Development and implementation of a measurement system for PTW water phantom in the determination of absorbed dose to water

Authors

DOI:

https://doi.org/10.15392/2319-0612.2024.2473

Keywords:

Metrology and dosimetry, absorbed dose to water, dosimeter system, water phantom

Abstract

At Secondary Standard Dosimetry Laboratory (SSDL) in Venezuela is the only one in the country that performs calibrations of dosimetry systems with an IAEA water phantom. However, SSDL has a PTW water phantom, for which there is no procedure for the calibration of dosimetry systems. Therefore, a methodology was developed for its validation using a cobalt-60 equipment, a secondary standard, an IAEA water phantom and a PTW phantom. The adapter for ionization chamber type NE 2561 was studied and designed to protect it from water. The methodology consisted of calculate of absorbed dose rate to water in IAEA water phantom and PTW water phantom. Subsequently, the absorbed dose rates to water were compared between both phantoms and finally, the validation of the new procedures and their respective uncertainties was performed. The adapter of ionization chamber was built with PMMA material. Comparisons between absorbed dose rates to water showed that there is no difference between the two phantoms. The absorbed dose rate to water was calculated with the procedure updates along with their associated uncertainties, obtaining =0.13482 ± 0.00292 Gy/min. Finally, the validation obtained a value of less than 0.7%, which means that the implementation of the new procedures for the calibration of dosimetry systems is valid and applied at the SSDL-Venezuela.

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Author Biographies

  • Rodríguez, C., Venezuelan Institute for Scientific Research

    Master in medical physics.

    Head of Nuclear Technology Unit in Venezuelan Institute for Scientific Research.

     

  • Durán, J.A, Venezuelan Institute for Scientific Research

    Industrial Engineer. 

    Head of Secondary Standard Dosimetry Laboratory in Nuclear Technology Unit. 

References

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[5] IAEA, WHO. Callibration of reference dosimeters for external beam radiotherapy. Technical reports series N° 469. IAEA, Viena, 2009.

[6] JCGM. Evaluation of measurement data. Guide to the expression of uncertainty in measurement. First Edition. España. 2008.

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[8] ISO/IEC. General requirements for the competence of testing and calibration laboratories. Second Edition, 2005.

[9] ZARETKY, A., SARAVÍ, M., STEFANIC, A., MONTAÑO, G., & VALLEJOS, M. Optimization and validation for the calibration procedure of a dosimeter for radiotherapy in air and water, in cobalt 60. Metrology Symposium. National Metrology Center. 2010.

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Published

2025-01-07

How to Cite

Development and implementation of a measurement system for PTW water phantom in the determination of absorbed dose to water. Brazilian Journal of Radiation Sciences, Rio de Janeiro, Brazil, v. 12, n. 3A (Suppl.), p. e2473, 2025. DOI: 10.15392/2319-0612.2024.2473. Disponível em: https://www.bjrs.org.br/revista/index.php/REVISTA/article/view/2473. Acesso em: 1 may. 2025.