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Statistical analysis on 2D array of ion chamber performance

  • Akbar Anvari (a1), Seyed Mahmoud Reza Aghamiri (a1), Seyed Rabie Mahdavi (a2) and Parham Alaei (a3)



In this work, dosimetric properties of the PTW Octavius detector in and out of the irradiation field have been evaluated. The 2D array of ion chambers has the potential to simplify the linear accelerator QA and pre-treatment verification.

Materials and methods

The evaluation was performed using customised written codes in Matlab and SPSS software for statistical analysis.


Experiments indicate that the reproducibility and stability of the measurements were excellent; the detector showed the same signal with a maximum deviation of <0·5% in the short and long term. Comparisons of the ion chamber with the detector showed the same results with a maximum deviation of ~0·1%. As the detector response is linear with the dose, it can be used for the measurement at regions of high-dose gradient effectively. Logarithmic regression y=0·127 ln(x)+0·729 for detector signal and field size changes yielded a coefficient of determination of 0·997. The dose value decreases with increase in source-to-surface distance, which was modelled using a binomial regression with a coefficient of determination of 0·998 that agrees with the ionisation chamber measurement within 1%.


On the basis of the measurements and comparisons performed, this system is a reliable and accurate dosimeter for quality assurance in radiotherapy.


Corresponding author

Correspondence to: Akbar Anvari, Department of Radiation Medicine Engineering, Shahid Beheshti University, Tehran 19839-63113, Iran. Tel.: +98 21 29902541. E-mail:


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Statistical analysis on 2D array of ion chamber performance

  • Akbar Anvari (a1), Seyed Mahmoud Reza Aghamiri (a1), Seyed Rabie Mahdavi (a2) and Parham Alaei (a3)


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