Skip to main content Accessibility help
×
Home

Quality assurance of linear accelerator: a comprehensive system using electronic portal imaging device

  • P. Niyas (a1) (a2) (a3), K. K. Abdullah (a1), M. P. Noufal (a2) and R. Vysakh (a3)

Abstract

Aim

The Electronic Portal Imaging Device (EPID), primarily used for patient setup during radiotherapy sessions is also used for dosimetric measurements. In the present study, the feasibility of EPID in both machine and patient-specific quality assurance (QA) are investigated. We have developed a comprehensive software tool for effective utilisation of EPID in our institutional QA protocol.

Materials and methods

Portal Vision aS1000, amorphous silicon portal detector attached to Clinac iX—Linear Accelerator (LINAC) was used to measure daily profile and output constancy, various Multi-Leaf Collimator (MLC) checks and patient plan verification. Different QA plans were generated with the help of Eclipse Treatment Planning System (TPS) and MLC shaper software. The indigenously developed MATLAB programs were used for image analysis. Flatness, symmetry, output constancy, Field Width at Half Maximum (FWHM) and fluence comparison were studied from images obtained from TPS and EPID dosimetry.

Results

The 3 years institutional data of profile constancy and patient-specific QA measured using EPID were found within the acceptable limits. The daily output of photon beam correlated with the output obtained through solid phantom measurements. The Pearson correlation coefficients are 0.941 (p = 0.0001), 0.888 (p = 0.0188) and 0.917 (p = 0.0007) for the years of 2014, 2015 and 2016, respectively. The accuracy of MLC for shaping complex treatment fields was studied in terms of FWHM at different portions of various fields, showed good agreement between TPS-generated and EPID-measured MLC positions. The comparison of selected patient plans in EPID with an independent 2D array detector system showed statistically significant correlation between these two systems. Percentage difference between TPS computed and EPID measured fluence maps calculated for number of patients using MATLAB code also exhibited the validity of those plans for treatment.

Copyright

Corresponding author

Author for correspondence: P. Niyas, Akayi Potta, Farook College, Calicut 673632, Kerala, India. Tel: +91 9847814131. E-mail: pniyas@gmail.com

Footnotes

Hide All

Cite this article: Niyas P, Abdullah KK, Noufal MP, Vysakh R. (2019) Quality assurance of linear accelerator: a comprehensive system using electronic portal imaging device. Journal of Radiotherapy in Practice18: 138–149. doi: 10.1017/S146039691800050X

Footnotes

References

Hide All
1. Kutcher, GJ, Coia, L, Gillin, M et al. Comprehensive QA for radiation oncology: report of AAPM Radiation Therapy Committee Task Group 40. Med Phys 1994; 21 (4): 581618.
2. Klein, EE, Hanley, J, Bayouth, J et al. Task Group 142 report: quality assurance of medical accelerators. Med Phys 2009; 36 (9): 41974212.
3. Fraass, B, Doppke, K, Hunt, M et al. American Association of Physicists in Medicine Radiation Therapy Committee Task Group 53: quality assurance for clinical radiotherapy treatment planning. Med Phys 1998; 25: 17731829.
4. McKenzie, EM, Balter, PA, Stingo, FC, Jones, J, Followill, DS, Kry, SF. Toward optimizing patient-specific IMRT QA techniques in the accurate detection of dosimetrically acceptable and unacceptable patient plans. Med Phys. 2014; 41 (12): 121702.
5. Pasma, KL, Dirkx, ML. P, Kroonwijk, M, Visser, AG, Heijmen, BJM. Dosimetric verification of intensity modulated beams produced with dynamic multileaf collimation using an electronic portal imaging device. Med Phys 1999; 26: 23732378.
6. Talamonti, C, Casati, M, Bucciolini, M. Pretreatment verification of IMRT absolute dose distributions using a commercial a Si-EPID. Med Phys 2006; 33: 43674378.
7. Lee, C, Menk, F, Cadman, P, Greer, PB. A simple approach to using an amorphous silicon EPID to verify IMRT planar dose maps. Med Phys 2009; 36: 984992.
8. Esch, AV, Huyskens, DP, Hirschi, L, Scheib, S, Baltes, C. Optimized Varian a Si portal dosimetry: development of datasets for collective use. J Appl Clin Med Phys 2013; 14: 8299.
9. Vieira, SC, Bolt, RA, Dirkx, MLP, Visser, AG, Heijmen, BJM. Fast, daily linac verification for segmented IMRT using electronic portal imaging. Radiother Oncol 2006; 80 (1): 8692.
10. Yang, Y, Xing, L. Quantitative measurement of MLC leaf displacements using an electronic portal image device. Phys Med Biol 2004; 49: 15211533.
11. Parent, L, Seco, J, Evans, PM, Dance, DR, Fielding, A. Evaluation of two methods of predicting MLC leaf positions using EPID measurements. Med Phys 2006; 33: 31743182.
12. Chang, J, Obcemea, CH, Sillanpaa, J, Mechalakos, J, Burman, C. Use of EPID for leaf position accuracy QA of dynamic multi-leaf collimator (DMLC) treatment. Med Phys 2004; 31: 20912096.
13. 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: 289309.
14. Hossain, M, Rhoades, J. On beam quality and flatness of radiotherapy megavoltage photon beams. Austral Phys Eng Sci Med 2016; 39 (1): 135145.
15. Nath, R, Biggs, PJ, Bova, FJ, Ling, CC, Purdy, JA, van de Geijn, J et al. AAPM code of practice for radiotherapy accelerators: report of AAPM Radiation Therapy Task Group No. 45. Med Phys 1994; 21: 10931121.
16. Rangel, A, Dunscombe, P. Tolerances on MLC leaf position accuracy for IMRT delivery with a dynamic MLC. Med Phys 2009; 36: 33043309.
17. Mamalui-Hunter, M, Li, H, Low, DA. MLC quality assurance using EPID: a fitting technique with sub pixel precision. Med Phys 2008; 35: 23472355.
18. Anup Kumar, B, Suresh Chander, S, Bhupendra, R, Arvind, S. Study of 2D ion chamber array for angular response and QA of dynamic MLC and pretreatment IMRT plans. Pract Oncol Radiother 2009; 14 (3): 8994.
19. Niyas, P, Abdullah, KK, Noufal, MP et al. Effect of fluence smoothing on the quality of intensity-modulated radiation treatment plans. Radiol Phys Technol 2016; 9: 202.
20. Nelms, BE, Simon, JA. A survey on IMRT QA analysis. J App Clin Med Phys 2007; 8 (3): 7690.
21. Bucciolini, M, Bounamici, FB, Casati, M. Verification of IMRT fields by film dosimetry. Med Phys 2004; 31 (1): 161168.
22. Ju, SG, Ahn, YC, Huh, SJ, Yeo, IJ. Film dosimetry for intensity modulated radiotherapy: dosimetric evaluation. Med Phys 2002; 29 (3): 315325.
23. Tyler, M, Vial, P, Metcalfe, P, Downes, S. Clinical validation of an in-house EPID dosimetry system for IMRT QA at the Prince of Wales Hospital. J Phys Conf Ser 2013; 444 (012043): 14.
24. Heilemann, G, Poppe, B, Laub, W. On the sensitivity of common gamma-index evaluation methods to MLC misalignments in Rapidarc quality assurance. Med Phys 2013; 40 (3): 031702.
25. Saminathan, S, Manickan, R, Chandraraj, V, Supe, SS. Dosimetric study of 2D ion chamber array matrix for the modern radiotherapy treatment verification. J Appl Clin Med Phys 2010; 11: 116127.
26. Bailey, DW, Kumaraswamy, L, Bakhtiari, M, Malhotra, HK, Podgorsak, MB. EPID dosimetry for pretreatment quality assurance with two commercial systems. J Appl Clin Med Phys 2012; 13 (4): 8299.
27. McDermott, LN, Wendling, M, Sonke, JJ, van Herk, M, Mijnheer, BJ. Replacing pretreatment verification with in-vivo EPID dosimetry for prostate IMRT. Int J Radiat Oncol Biol Phys 2007; 67 (5): 15681577.
28. Mans, A, Wendling, M, McDermott, LN et al. Catching errors with in vivo EPID dosimetry. Med Phys 2010; 37 (6): 26382644.

Keywords

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed