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The sensitivity of gamma index analysis to detect multileaf collimator (MLC) positioning errors using Varian TrueBeam EPID and ArcCHECK for patient-specific prostate volumetric-modulated arc therapy (VMAT) quality assurance

Published online by Cambridge University Press:  11 July 2017

Borna Maraghechi ,
Jack Davis ,
Nicholas Mitchell ,
Meeral Shah ,
Andre Fleck ,
Johnson Darko  and
Ernest Osei
Borna Maraghechi
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada
Jack Davis
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada
Nicholas Mitchell
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada
Meeral Shah
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada
Andre Fleck
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
Johnson Darko
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
Ernest Osei*
Affiliation:
Department of Medical Physics, Grand River Regional Cancer Centre, Kitchener, ON, Canada Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada Department of Systems Design, University of Waterloo, Waterloo, ON, Canada
*
Correspondence to: Dr Ernest Osei, Department of Medical Physics, Grand River Regional Cancer Centre, 835 King St W, Kitchener, ON, Canada, N2G 1G3. Tel: 519 749 4300, Ext: 5407. E-mail: ernest.osei@grhosp.on.ca
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Abstract

Background

Due to the increased degree of modulation and complexity of volumetric-modulated arc therapy (VMAT) plans, it is necessary to have a pre-treatment patient-specific quality assurance (QA) programme. The gamma index is commonly used to quantitatively compare two dose distributions. In this study we investigated the sensitivity of single- and multi-gamma criteria techniques to detect multileaf collimator (MLC) positioning errors using the Varian TrueBeam Electronic Portal Imaging DeviceTM (EPID) dosimetry and the ArcCHECKTM device.

Materials and methods

All active MLC positions of seven intact prostate patients VMAT plans were randomly changed with a mean value of 0.25, 0.5, 1 and 2 mm and a standard deviation of 0.1 mm on 25, 50, 75 and 100% of the control points. The change in gamma passing rates of six gamma criteria of 3%/3 mm, 3%/2 mm, 3%/1 mm, 2%/2 mm, 2%/1 mm and 1%/1 mm were analysed individually (single-gamma criterion) and as a group (multi-gamma criteria) as a function of the simulated errors. We used the improved and global gamma calculation algorithms with a low dose threshold of 10% in the EPID and ArcCHECK software, respectively. The changes in the planning target volume dose distributions and the organs at risk due to the MLC positioning errors were also studied.

Results

When 25, 50, 75 and 100% of the control points were modified by the introduction of the simulated errors, the smallest detectable errors with the EPID were 2, 1, 0.5 and 0.5 mm, respectively, using the multi-gamma criteria technique. Similarly for the single-gamma criteria technique errors as small as 2, 1, 1 and 1 mm applied to 25, 50, 75 and 100% of the control points, respectively, were detectable using a 2%/2 mm criterion. However, the smallest detectable errors with the ArcCHECK when using the multi-gamma criteria technique were 2, 2 and 1 mm when MLC errors were applied on 50, 75 and 100% of the control points. When only 25% of the control points were affected the ArcCHECK were unable to detect any of the errors applied. No noticeable difference was observed in the sensitivity using the single- or the multi-gamma criteria techniques with the ArcCHECK.

Conclusion

The Varian TrueBeam EPID dosimetry shows a higher sensitivity in detecting MLC positioning errors compared with the ArcCHECK regardless of using the single- or the multi-gamma criteria techniques. Higher sensitivity was observed using the multi-gamma criteria technique compared with the single-criterion technique when using the EPID.

Keywords

ArcCHECKEPID dosimetrygamma indexprostate cancerVMAT quality assurance
Type
Original Articles
Information
Journal of Radiotherapy in Practice , Volume 17 , Issue 1 , March 2018 , pp. 66 - 77
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Copyright
© Cambridge University Press 2017 

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References

REFERENCES

1. Kim, J I, Park, S Y, Kim, H J, Kim, J H, Ye, S J, Park, J M. The sensitivity of gamma-index method to the positioning errors of high-definition MLC in patient-specific VMAT QA for SBRT. Radiat Oncol 2014; 9: 167–178.Google Scholar
2. Low, D A, Harms, W B, Mutic, S, Purdy, J A. A technique for the quantitative evaluation of dose distributions. Med Phys 1998; 25: 656–661.Google Scholar
3. Liang, B, Liu, B, Zhou, F, Yin, F, Wu, Q. Comparisons of volumetric modulated arc therapy (VMAT) quality assurance (QA) systems: sensitivity analysis to machine errors. Radiat Oncol 2016; 11: 1–10.Google Scholar
4. 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: 031702.CrossRefGoogle ScholarPubMed
5. Fredh, A, Scherman, J B, Fog, L S, Munck af Rosenschold, P. Patient QA systems for rotational radiation therapy: a comparative experimental study with intentional errors. Med Phys 2013; 40: 031716.Google Scholar
6. Coleman, L, Skourou, C. Sensitivity of volumetric modulated arc therapy patient specific QA results to multileaf collimator errors and correlation to dose volume histogram based metrics. Med Phys 2013; 40: 111715.Google Scholar
7. Oliver, M, Gagne, I, Bush, K, Zavgorodni, S, Ansbacher, W, Beckham, W. Clinical significance of multi-leaf collimator positional errors for volumetric modulated arc therapy. Radiother Oncol 2010; 97: 554–560.Google Scholar
8. Stasi, M, Bresciani, S, Miranti, A, Maggio, A, Sapino, V, Gabriele, P. Pretreatment patient-specific IMRT quality assurance: a correlation study between gamma index and patient clinical dose volume histogram. Med Phys 2012; 39: 7626.Google Scholar
9.Varian Medical Systems. Portal imaging and portal dosimetry reference guide. Palo Alto, CA USA: Varian Medical Systems, 2008.Google Scholar
10. Vieillevigne, L, Molinier, J, Brun, T, Ferrand, R. Gamma index comparison of three VMAT QA Systems and evaluation of their sensitivity to delivery errors. Phys Med 2015; 31: 720–725.Google Scholar
11. Steers, J M, Fraass, B A. IMRT QA: selecting gamma criteria based on error detection sensitivity. Med Phys 2016; 43: 1982–1994.Google Scholar
12. Park, J I, Park, J M, Kimb, J I, Parkb, S Y, Ye, S J. Gamma-index method sensitivity for gauging plan delivery accuracy of volumetric modulated arc therapy. Phys Med 2015; 31: 1118–1122.Google Scholar
13. Nelms, B E, Chan, M F, Jarry, G et al. Evaluating IMRT and VMAT dose accuracy: practical examples of failure to detect systematic errors when applying a commonly used metric and action levels. Med Phys 2013; 40: 111722–111736.CrossRefGoogle ScholarPubMed
14. Quino, L V, Hernandez, C H, Morrow, A, Massingill, B, Rangaraj, D. SU-F-T-308: mobius FX evaluation and comparison against a commercial 4D detector array for VMAT plan QA. Med Phys 2016; 43 (6): 3533–3534.Google Scholar
15. Vieillevigne, L, Molinier, J, Brun, T, Ferrand, R. Gamma index comparison of three VMAT QA systems and evaluation of their sensitivity to delivery errors. Phys Med 2015; 31 (7): 720–725.Google Scholar
16. Darko, J, Kiciak, A, Badu, S, Grigorov, G, Fleck, A, Osei, E. SU-F-T-272: patient specific quality assurance of prostate VMAT plans with portal dosimetry. Med Phys 2016; 43 (6): 3525.Google Scholar