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Effect of computed tomography number-relative electron density conversion curve on the calculation of radiotherapy dose and evaluation of Monaco radiotherapy treatment planning system

Australasian Physical & Engineering Sciences in Medicine volume 42, pages 489–502 (2019)Cite this article

Abstract

The accuracy of a computed tomography (CT)-relative electron density (RED) curve may have an indirect impact on the accuracy of dose calculation by a treatment planning system (TPS). This effect has not been previously quantified for input of different CT-RED curves from different CT-scan units in the Monaco TPS. This study aims to evaluate the effect of CT-RED curve on the dose calculation by the Monaco radiotherapy TPS. Four CT images of the CIRS phantom were obtained by different CT scanners. The accuracy of the dose calculation in the three algorithms of the Monaco TPS (Monte Carlo, collapse cone, and pencil beam) is also evaluated based on TECDOC 1583. The CT-RED curves from the CT scanners were transferred to the Monaco TPS to audit the different algorithms of the TPS. The dose values were measured with an ionization chamber in the CIRS phantom. Then, the dose values were calculated by the Monaco algorithms in the corresponding points. For the Monaco TPS and based on TECDOC 1583, the accuracy of the dose calculation in all the three algorithms is within the agreement criteria for most of the points evaluated. For low dose regions, the differences between the calculated and measured dose values are higher than the agreement criteria in a number of points. For the majority of the points, the algorithms underestimate the calculated dose values. It was also found that the use of different CT-RED curves can lead to minor discrepancies in the dose calculation by the Monaco TPS, especially in low dose regions. However, it appears that these differences are not clinically significant in most of the cases.

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Acknowledgements

The authors would like to thank Shahid Beheshti University of Medical Sciences for financial support of the current study.

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Affiliations

  1. Department of Radiotherapy Physics, Cancer Research Centre, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran

    Mohsen Hasani

  2. Department of Medical Physics and Radiology, Faculty of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran

    Bagher Farhood

  3. Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran

    Mahdi Ghorbani

  4. Department of Radiotherapy Physics, Cancer Institute, Qom University of Medical Sciences, Qom, Iran

    Hamideh Naderi, Sepideh Saadatmand & Saeed Karimkhani Zandi

  5. Comprehensive Cancer Centers of Nevada, Las Vegas, NV, USA

    Courtney Knaup

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  1. Mohsen Hasani
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  2. Bagher Farhood
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Correspondence to Bagher Farhood or Mahdi Ghorbani.

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Hasani, M., Farhood, B., Ghorbani, M. et al. Effect of computed tomography number-relative electron density conversion curve on the calculation of radiotherapy dose and evaluation of Monaco radiotherapy treatment planning system. Australas Phys Eng Sci Med 42, 489–502 (2019). https://doi.org/10.1007/s13246-019-00745-6

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  • DOI: https://doi.org/10.1007/s13246-019-00745-6

Keywords

  • CT-RED curve
  • Radiotherapy
  • Treatment planning system
  • Audit
  • Monaco