An Empirical Transmitted EPID Dosimetry Method using a Back-Projection Algorithm.
Algorithms
Dose-Response Relationship
Radiotherapy
Radiotherapy Planning, Computer-Assisted
Journal
Journal of biomedical physics & engineering
ISSN: 2251-7200
Titre abrégé: J Biomed Phys Eng
Pays: Iran
ID NLM: 101589641
Informations de publication
Date de publication:
Oct 2019
Oct 2019
Historique:
received:
12
12
2018
accepted:
25
01
2019
entrez:
22
11
2019
pubmed:
22
11
2019
medline:
22
11
2019
Statut:
epublish
Résumé
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. 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. 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. Based on the results, the method proposed can be used in EPID dosimetry.
Sections du résumé
BACKGROUND
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
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
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
CONCLUSIONS
Based on the results, the method proposed can be used in EPID dosimetry.
Identifiants
pubmed: 31750269
doi: 10.31661/jbpe.v0i0.1082
pii: JBPE-9-5
pmc: PMC6820021
doi:
Types de publication
Journal Article
Langues
eng
Pagination
551-558Informations de copyright
Copyright: © Shiraz University of Medical Sciences.
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