Enhance dynamic wedge verification by using electronic portal imaging device

Authors

  • Saiyo N School of Radiological Technology, Faculty of Health Science Technology / 3Radiation Oncology Department, Chulabhorn Hospital, HRH Princess Chulabhorn College of medical Science, Chulabhorn Royal Academy
  • Thongsawad S Medical Physics Program, Faculty of Medicine and Public Health / Radiation Oncology Department, Chulabhorn Hospital, HRH Princess Chulabhorn College of medical Science, Chulabhorn Royal Academy
  • Changphong P Radiological Technology Division, Faculty of Science, Ramkhamhaeng University
  • Khotsawan T Radiological Technology Division, Faculty of Science, Ramkhamhaeng University
  • Nilsetkurawat N Radiological Technology Division, Faculty of Science, Ramkhamhaeng University
  • Phongphiriyadecha K Radiological Technology Division, Faculty of Science, Ramkhamhaeng University

Keywords:

electronic portal imaging device, enhance dynamic wedges, beam profile verification

Abstract

Objectives  The purpose of this study was to verify the 80% enhanced dynamic wedge (EDW) beam profile using an electronic portal imaging device (EPID).

Methods  This study investigated symmetric and asymmetric field sizes using a 6 MV photon beam. Verification of the wedge output factor with an 80% beam profile was performed by comparing EPID measurements and treatment planning systems (TPS) calculations in both symmetric and asymmetric field sizes at different wedge angles (15, 30, 45, and 60 degrees).

Results For the symmetric field size, the average difference between the measured and calculated beam profile was less than 2% (range 0.57-1.12%). For the asymmetric field size, the difference was also less than 2% (range 0.3-0.52%).

Conclusion  This study indicates that EPID can be used to verify the 80% enhanced dynamic wedge beam profile at different field sizes and wedge angles. The difference in beam profiles was less than 2% which is in accordance with AAPM TG no.142 recommendations.

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References

1. Akasaka H, Mukumoto N, Nakayama M, Wang T, Yada R, Shimizu Y, et al. A Comparison of Physical vs. Nonphysical Wedge Modalities in Radiotherapy. Radiotherapy. 2017;1:17:251.
2. Shalek RJ. Determination of absorbed dose in a patient irradiated by beams of x or gamma rays in radiotherapy procedures. Medical Physics. 1977;4:461.
3. Klein EE, Hanley J, Bayouth J, Yin FF, Simon W, Dresser S, et al. Task Group 142 report: Quality assurance of medical acceleratorsa. Med Phys. 2009;36:4197-212.
4. Nelms BE, Rasmussen KH, Tomé WA. Evaluation of a fast method of EPID-based dosimetry for intensity-modulated radiation therapy. Appl Clin Med Phys. 2010;11:3185
5. Van Elmpt W, McDermott L, Nijsten S, Wendling M, Lambin P, Mijnheer B. A literature review of electronic portal imaging for radiotherapy dosimetry. Radiother Oncol. 2008; 88:289-309.
6. Van Esch A, Depuydt T, Huyskens DP. The use of an aSi-based EPID for routine absolute dosimetric pre-treatment verification of dynamic IMRT fields. Radiother Oncol. 2004; 71:223-34.
7. McCurdy BM, Greer PB. Dosimetric properties of an amorphous-silicon EPID used in continuous acquisition mode for application to dynamic and arc IMRT. Med Phys. 2009;36:3028-39.
8. Kirby MC, Glendinning AG. Developments in electronic portal imaging systems. Br J Radiol. 2006;79 spec:S50-65.
9. Syam KS, Aparna P, Shelly JJ, Geetha S. Comparison of Beam Profiles and Wedge Factors for Physical and Enhanced Dynamic Wedge. Int J Radiol Radiat Ther. 2018;5:32-6.
10. Petrovic B, Grzadziel A, Rutonjski L, Slosarek K. Linear array measurements of enhanced dynamic wedge and treatment planning system (TPS) calculation for 15 MV photon beam and comparison with electronic portal imaging device (EPID) measurements. Radiother Oncol. 2010;44:199-206.
11. Mekuria Y, Bjorkqvist M, Kulmala J. Quality control and pretreatment quality assurance application of EPID (as1000) for FF and FFF beam VMAT plans. MPI Journal. 2015;3:120-5.
12. Tehovnik T. Three-dimensional dose verification for intensity modulated radiation therapy (IMRT) using an amorphous silicon electronic portal imaging device (EPID) [thesis]. Northfields Ave, Wollongong, NSW: University of Wollongong; 2011.
13. Das IJ, Cheng CW, Watts RJ, Ahnesjö A, Gib­bons J, Li XA, et al. Accelerator beam data commissioning equipment and procedures: report of the TG-106 of the Therapy Physics Committee of the AAPM. Med Phys. 2008;35:4186-215.
14. Greer PB. Correction of pixel sensitivity variation and off-axis response for amorphous silicon EPID dosimetry. Med Phys. 2005;32:3558-68.
15. Greer PB, Barnes MP. Investigation of an amorphous silicon EPID for measurement and quality assurance of enhanced dynamic wedge. Phys Med Biol. 2007;52:1075-87.
16. Shahnawaz A, Subrat SK, Vinod GK, Ahmad SI. Comprehensive study of Varian’s Enhanced Dynamic Wedge and Physical Wedge. J Appl Phys. 2017;9:1-8.
17. Prado KL, Kirsner SM, Kudchadker RJ, Steadham RE, Lane RG. Enhanced dynamic wedge factors at off-axis points in asymmetric fields. J Appl Clin Med Phys. 2003;4:75-84
18. Ko L, Kim JO, Siebers JV. Investigation of the optimal backscatter for an aSi electronic portal imaging device. Phys Med Biol. 2004;49: 1723-38.

Published

2021-04-01

How to Cite

1.
N S, S T, P C, T K, N N, K P. Enhance dynamic wedge verification by using electronic portal imaging device . Chiang Mai Med J. [Internet]. 2021 Apr. 1 [cited 2022 Jan. 26];60(2):175-86. Available from: https://he01.tci-thaijo.org/index.php/CMMJ-MedCMJ/article/view/249799

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Original Article