An empirical transmitted epid dosimetry method using a back-projection algorithm

Hashemi, S. M. and Bahreyni, M. H. and Mohammadi, M. and Nas-Seri, S. and Bayani, S. and Gholamhosseinian, H. and Salek, R. and Shahe-Di, F. and Momennezhad, M. (2019) An empirical transmitted epid dosimetry method using a back-projection algorithm. Journal of Biomedical Physics and Engineering, 9 (5). pp. 551-558.

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Background: The present study aimed to introduce a rapid transmission dosimetry through an electronic portal-imaging device (EPID) to achieve two-dimensional (2D) dose distribution for homogenous environments. Material and Methods: In this Phantom study, first, the EPID calibration curve and correction coefficients for field size were obtained from EPID and ionization chamber. Second, the EPID off-axis pixel response was measured, and the grey-scale image of the EPID was converted into portal dose image using the calibration curve. Next, the scattering contribution was calculated to obtain the primary dose. Then, by means of a verified back-projection algorithm and the Scatter-to-Primary dose ratio, a 2D dose distribution at the mid-plane was obtained. Results: The results obtained from comparing the transmitted EPID dosimetry to the calculated dose, using commercial treatment planning system with gamma function while there is 3 dose difference and 3mm distance to agreement criteria, were in a good agreement. In addition, the pass rates of γ < 1 was 94.89 for the homogeneous volumes. Conclusion: Based on the results, the method proposed can be used in EPID dosimetry. © 2019, Shiraz University of Medical Sciences. All rights reserved.

Item Type: Article
Additional Information: Export Date: 16 February 2020 Correspondence Address: Momennezhad, M.; Medical Physics Research Center, Mashhad University of medical ScienceIran; email:
Uncontrolled Keywords: Algorithms Computer-Assisted Dose-Response Relationship Radiotherapy Radiotherapy Planning Article comparative study dosimetry evaluation study filtered back projection image reconstruction mathematical model measurement accuracy Monte Carlo method nonhuman radiation dose distribution treatment planning two-dimensional imaging
Subjects: QT physiology
Divisions: Mashhad University of Medical Sciences
Depositing User: mr lib1 lib1
Date Deposited: 21 Jun 2020 06:36
Last Modified: 21 Jun 2020 06:36

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