Radiation Physics and Engineering
A peer-reviewed journal published by K. N. Toosi University of Technology

A computational approach for assessing calibration factors of narrow beam X-ray dosimeters at the SSDL: A feasibility study

Articles in Press

Document Type : Research Article

Authors

Nahid Hajiloo 1
Shahryar Malekie 1
Seyed Musa Safdari 2

1 Radiation Application Research School, Nuclear Science and Technology Research Institute, P.O. Box 31486-43111, Karaj, Iran

2 Secondary Standard Dosimetry Laboratory, Parsisotope Company, Karaj, Iran

https://doi.org/10.22034/rpe.2026.552068.1306
Abstract
This feasibility study explores a computational method for estimating air-kerma calibration factors (NK) of narrow-beam X-ray dosimeters at Secondary Standard Dosimetry Laboratories (SSDLs) in resource-limited settings. Using mass attenuation coefficient ratios interpolated from NIST data, analytical calculations yielded calibration factors for the 30-cc PTW spherical ionization chamber under the ISO 4037 N-60 (mean energy of 47.9 keV) and N-80 (mean energy of 65.2 keV) qualities, referenced to Co-60 and Cs-137. Deviations from IAEA-traceable values were recorded as 1.1% (for N-80) and 6.8% (for N-60) using the Co-60 as reference energy, and 3.0% (for N-80) and 8.9% (for N-60) using the Cs-137. Independent MCNP4C Monte Carlo simulations captured energy-dependent trends but showed larger discrepancies (8.6-13.4%). This method serves as a useful supplementary tool that supports standard experimental calibration (with expanded uncertainty, k=2: 1.8-3.5%). However, it has limitations due to the lack of new experimental measurements and reliance on computational assumptions, which require additional validation.

Highlights

  • A computational method was employed to determine the calibration factor of a standard dosimeter.
  • The 30-cc PTW spherical ion chamber was evaluated in X-ray fields N-60 and N-80.
  • Calculations showed agreement with the IAEA, with deviations ranging from 1.1% to 8.9%.
  • MCNP simulations reproduced energy-dependent trends (deviation of 8.6% to 13.4%).
  • The method provides a cost-effective alternative to experimental calibration.

Keywords

Computational dosimetry
Calibration Factor
30-cc PTW spherical ion chamber
X-ray Fields
IAEA Standards
Uncertainty

Subjects

Copyright
RPE is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Conflict of Interest
The authors declare no potential conflict of interest regarding the publication of this work‎.

Funding
‎The authors declare that no funds‎, ‎grants‎, ‎or other financial support were received during the preparation of this manuscript‎.

Abidin, H. Z., Mukhtar, N. M. A., Mahmood, A., et al. (2025). A Systematic Review on the Radiation Shielding Performance of Metal-Polymer Composites. Malaysian Journal of Applied Sciences, 10(2):63–93.
Agency, I. A. E. (2007). Dosimetry in Diagnostic Radiology. International Atomic Energy Agency.
Aghdam, S. R. H., Aghamiri, S. M. R., Malekie, S., et al. (2023a). Evaluating the linearity response for a PVA/MWCNT-OH nanocomposite dosimeter in photon beam of linear accelerator. Radiation Physics and Chemistry, 210:111044.
Aghdam, S. R. H., Aghamiri, S. M. R., Malekie, S., et al. (2023b). Performance characteristics of a parallel plate dosimeter based on PVA/MWCNT-OH nanocomposite for photon beam radiation. Measurement, 207:112419.
Attix, F. H. (2008). Introduction to radiological physics and radiation dosimetry. John Wiley & Sons.
Berger, M. (2010). XCOM: photon cross sections database. http://www. nist. gov/pml/data/xcom/index. cfm.
Briesmeister, J. (2005). MCNP4C-Monte Carlo N-Particle transport code system version 4C. Los Alamos National Laboratory, Los Alamos, New Mexico, 1.
Burns, D. and Büermann, L. (2009). Free-air ionization chambers. Metrologia, 46(2):S9–S23.
Commission, I. E. (2005). IEC 31267: Medical diagnostic X-ray equipment-Radiation conditions for use in the determination of characteristics.
Dozik, Y. V. (2001). Calibration of radiation protection monitoring instruments; Graduirovka dozimetricheskikh priborov. Atomnaya Tekhnika za Rubezhom.
Hajiloo, N., Mohammadi, M., Ghasemifard, F., et al. (2025). Design and construction of a quality control phantom for evaluation of the clinical imaging performance of electronic portal imaging devices. Radiation Physics and Engineering, 6(4):39–45.
Hajiloo, N., Mohammadi, M., Ghodsi, O. N., et al. (2024). Comparison audit program for selected radiotherapy centers by secondary standard dosimetry laboratory (SSDL) using thermoluminescence dosimeter. Radiation Physics & Engineering, 5(2).
ISO-4037-1 (1996). X and Gamma Reference Radiation for Calibrating Dosemeters and Doserate Meters and for Determining Their Response as a Function of Photon Energy: Rayonnements X Et Gamma de Référence Pour L’étalonnage Des Dosimètres Et Des Débitmètres, Et Pour la Détermination de Leur Réponse en Fonction de L’energie Des Photons. Radiation Characteristics and Production Methods. Caractéristiques Des Rayonnements Et Méthodes de Production. International Organization for Standardization.
Malekie, S., Aghdam, S. R. H., Aghamiri, S. M. R., et al. (2025). Exploration of dosimetry characteristics of PVA/MWCNT-OH nanocomposite for intraoperative electron radiotherapy. Radiation Measurements, 180:107345.
Malekie, S., Veiskarami, A., Kashian, S., et al. (2024). Evaluating the dosimetry response to gamma-rays in HDPE/Bi2O3 and PC/Bi2O3 nanocomposites. Radiation Physics and Engineering, 5(4):15–19.
Queiróz Filho, P. P. d. and Da Silva, C. (2018). Geant4 simulation of ion chambers response to 60Co spectrum of LN-MRI/IRD Shepherd 81-14D Radiator. In Journal of Physics: Conference Series, volume 975, page 012051. IOP Publishing.
RAHMAN, M. S. et al. (2015). Tribological and Physico-Chemical Properties of Electron Beam Irradiated Polyoxymethylene Copolymer (POM-C). PhD thesis.
Seuntjens, J. and Duane, S. (2009). Photon absorbed dose standards. Metrologia, 46(2):S39–S58.
Shahbazi, L., Sardari, D., Malekie, S., et al. (2025). Evaluation of a flexible thyroid shield in dental panoramic radiography utilizing bismuth oxide silicone rubber composite and Rando phantom. Scientific Reports.
Radiation Physics and Engineering

Articles in Press, Accepted Manuscript
Available Online from 19 February 2026

  • Receive Date 08 October 2025
  • Revise Date 24 December 2025
  • Accept Date 14 February 2026

Home

Submit Manuscript

Reviewers

Contact Us