Use of Amorphous Silicon (ASi) Electronic Portal Imaging Devices for Other applications for Linear Accelerator Quality Assurance

Document Type : Original Paper


1 Assiut Military Center for Radiotherapy, Assiut, Egypt

2 Faculty of Medicine, Al Azhar University, Egypt

3 Physics Department, Faculty of Science, New Valley University, 72511, El-Kharga, Egypt.

4 Physics Department, Faculty of Science, Al Azhar University, Assuit


Introduction: The success of radiation therapy depends critically on the accuracy of patient alignment in treatment position day after day. The primary use for Electronic portal imaging devices (EPIDs) is to monitor patient position during daily radiotherapy sessions. Recently the role of EPIDs has been expanded beyond patient imaging to become a useful tool for radiotherapy dosimetry.
Material and Methods: To test another application of linac quality assurance (QA), 10×10 cm2 and 18×18 cm2 images of an open field were obtained. The epidermis was located at a fixed detector distance of 150 cm. Results: Wedge profile and wedge factors with a high level of accuracy demonstrated. The profiles acquired using EPID deviated in shape and magnitude by up to 16% from the ion chamber profiles. The use of EPID for linac QA can be simplified by improving the available software analysis tools, which will increase its efficiency. According to the findings, the EPID aSi500 has the potential to be used as a relative dosimeter, making it a straightforward and efficient tool for daily QA.
Conclusion: All EPID measurements were performed using the linear accelerator Varian DMX. Based on the physical characteristics, as an efficient tool, the SLIC-EPID can be used for daily QA.


Main Subjects


    1. Gandhi A, Vellaiyan S, Subramanian VS, Shanmugam T, Murugesan K, Subramanian K. Commissioning of portal dosimetry using a novel method for flattening filter-free photon beam in a nontrue beam linear accelerator. Journal of cancer research and therapeutics. 2019 Jan 1;15(1):223.‏
    2. Jhala E. Investigation of Dosimetric Characteristics and Exploration of Potential Applications of Amorphous Silicon Detector. 2006.
    3. Langmack KA. Portal imaging. The British journal of radiology. 2001 Sep;74(885):789-804.
    4.  Sun B, Goddu SM, Mutic S, Cai B. EPID-based linear accelerator benchmarking using pixel sensitivity map. InJournal of Physics: Conference Series 2019 Aug 1; 1305(1):012063.
    5. Gena MA, El-Attar AL, Zahran EM, El-Gamal H, Aly MM. Development of the Use of Amorphous Silicon (ASi) Electronic Portal Imaging Devices as a Physics Tool for Routine Linear Accelerator QA.
    6. Liu G. The Application of Electronic Portal Imaging Devices to Radiotherapy Quality Assurance (Doctoral dissertation, University of Adelaide.‏ 2002.
    7. Kavuma A. Transit dosimetry based on water equivalent path length measured with an amorphous silicon electronic portal imaging device (Doctoral dissertation, University of Glasgow). 2011.
    8. De Koste JR, Cuijpers JP, de Geest FG, Lagerwaard FJ, Slotman BJ, Senan S. Verifying 4D gated radiotherapy using time-integrated electronic portal imaging: a phantom and clinical study. Radiation Oncology. 2007 Dec;2(1):1-9. ‏
    9. Lloyd PJ. Quality assurance workbook for radiographers and radiological technologists. World Health Organization.‏ 2001.
    10. Kirby MC, Glendinning AG. Developments in electronic portal imaging systems. The British journal of radiology. 2006 Sep;79(special_issue_1):S50-65. ‏
    11. Giraud P, De Rycke Y, Rosenwald JC, Cosset JM. Conformal radiotherapy planning for lung cancer: analysis of set-up uncertainties. Cancer investigation. 2007 Jan 1;25(1):38-46.
    12.  Pasler M, Hernandez V, Jornet N, Clark CH. Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques. Physics and Imaging in Radiation Oncology. 2018 Jan 1;5:76-84.
    13.  Gibbons JP. Calculation of enhanced dynamic wedge factors for symmetric and asymmetric photon fields. Medical physics. 1998 Aug;25(8):1411-8.
    14. Jacobs M, Nijsten SM, Lambin P, Minken AW. 6 Dosimetric calibration of a Siemens OptiVue 500 amorphous silicon electronic portal imaging device. Radiotherapy and Oncology. 2005(76):S15-6.