An Empirical Transmitted EPID Dosimetry Method using a Back- Projection Algorithm
| Autor: | S M Hashemi, R Salek, Hamid Gholamhosseinian, Sh. Bayani, Mohammad Mohammadi, M H Bahreyni, Fateme Shahedi, Mahdi Momennezhad, Shahrokh Nasseri |
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| Rok vydání: | 2019 |
| Předmět: |
lcsh:Medical physics. Medical radiology. Nuclear medicine
Physics Radiotherapy Radiological and Ultrasound Technology Pixel Calibration curve lcsh:R895-920 Radiotherapy Planning Computer-Assisted Epid dosimetry Bioengineering Imaging phantom Dose-Response Relationship Homogeneous Ionization chamber Dosimetry Original Article Radiology Nuclear Medicine and imaging Algorithm Back projection Algorithms |
| Zdroj: | Journal of Biomedical Physics & Engineering Journal of Biomedical Physics and Engineering, Vol 9, Iss 5, Pp 551-558 (2019) |
| ISSN: | 2251-7200 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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