Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Camera based EPID dosimetric verification of radiation treatments

Document Type : Conference Proceedings

Authors
Vahideh Nazari 1
Seied Rabi Mahdavi 2
Ahmad Mostaar 3
Hassan Nedaei 4
Mohammad Amin Mosleh Shirazi 5
Golbarg esmailie 2
1 Medical Physics Department, Faculty of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran.
2 Medical Physics Department, Iran University of Medical Sciences, Tehran, Iran
3 Medical Physics and Biomedical Engineering Department, Shahid Beheshti University of Medical Sciences, Tehran, Iran
4 Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran
5 Medical Physics Department, Shiraz University of Medical Sciences, Shiraz, Iran
10.22038/ijmp.2018.12840
Abstract
Introduction: Tumor control and treatment quality depend on accuracy of delivered dose. Various methods have been studied for treatment dosimetry verification. Among these methods, the use of electronic portal imaging device (EPID) is highly considered. Many efforts are underway to improve the results of this context.
 
Materials and Methods:
In this study, a new method for pretreatment dose verification is reported using the transmitted signal of a camera based EPID. Lateral scatter within imager has been considered as field size dependent additive operation. Lateral scatter description within the imager were obtained from measurements with a 2D array ionization chambers for a set of different field sizes. The water-equivalent thickness of phantom material was defined for dose reconstruction, by means of the treatment planning system, according to the patient's data in CT scans along the beam central axis.
 
Results:
The method was tested for pretreatment verification of 3D conformal prostate cancer treatment plans. There are no significant differences between the EPID and ionization chamber responses (P value = 0.37).
 
Conclusion:
This study proposes a practical method with easier and less calculations in comparison to the deconvolution approaches that can be applied for overall dosimetric assessments of treatments in every fraction.
Keywords
Camera based EPID
dosimetry verification

  • Receive Date 21 May 2018
  • Revise Date 30 April 2019
  • Accept Date 06 July 2018