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. 2019 Nov;20(11):80-87.
doi: 10.1002/acm2.12743. Epub 2019 Oct 11.

DVH analysis using a transmission detector and model-based dose verification system as a comprehensive pretreatment QA tool for VMAT plans: Clinical experience and results

Ahamed B Mohamed Yoosuf  1   2 , Salem AlShehri  1   3 , Abdulrahman Alhadab  1   3 , Mamdooh Alqathami  1   2   3
Affiliations

DVH analysis using a transmission detector and model-based dose verification system as a comprehensive pretreatment QA tool for VMAT plans: Clinical experience and results

Ahamed B Mohamed Yoosuf et al. J Appl Clin Med Phys. 2019 Nov.

Abstract

Purpose: Dose volume histogram (DVH)-based analysis is utilized as a pretreatment quality assurance tool to determine clinical relevance from measured dose which is difficult in conventional gamma-based analysis. In this study, we report our clinical experience with an ionization-based transmission detector and model-based verification system, using DVH analysis, as a comprehensive pretreatment QA tool for complex volumetric modulated arc therapy plans.

Methods and materials: Seventy-three subsequent treatment plans categorized into four clinical sites (Head and Neck, Thorax, Abdomen, and Pelvis) were evaluated. The average dose (Dmean ) and dose received by 1% (D1 ) of the planning target volumes (PTVs) and organs at risks (OARs) calculated using the treatment planning system (TPS) were compared to a computed (model-based) and reconstructed dose, from the measured fluence, using DVH analysis. The correlation between gamma (3% 3 mm) and DVH-based analysis for targets was evaluated. Furthermore, confidence and action limits for detector and verification systems were established.

Results: Linear regression confirmed an excellent correlation between TPS planned and computed dose using a model-based verification system (r2 = 1). The average percentage difference between TPS calculated and reconstructed dose for PTVs achieved using DVH analysis for each site is as follows: Head and Neck - 0.57 ± 2.8% (Dmean ) and 2.6 ± 2.7% (D1 ), Abdomen - 0.19 ± 2.8% and 1.64 ± 2.2%, Thorax - 0.24 ± 2.1% and 3.12 ± 2.8%, Pelvis 0.37 ± 2.4% and 1.16 ± 2.3%, respectively. The average percentage of passed gamma values achieved was above 95% for all cases. However, no correlation was observed between gamma passing rates and DVH difference (%) for PTVs (r2 = 0.11). The results demonstrate a confidence limit of 5% (Dmean and D1 ) for PTVs using DVH analysis for both computed and reconstructed dose distribution.

Conclusion: DVH analysis of treatment plan using a model-based verification system and transmission detector provided useful information on clinical relevance for all cases and could be used as a comprehensive pretreatment patient-specific QA tool.

Keywords: dose volume histogram analysis; ionization-based transmission detector; model-based verification system; volumetric modulated arc therapy.

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Conflict of interest statement

The authors declare that there is no conflict of interest regarding the publication of this article.

Figures

Figure 1
Figure 1
Comparison of treatment planning system calculated dose for planning target volume (mean) to: (a) Computed dose (CC algorithm) and (b) Compass reconstructed (measured using Dolphin detector).
Figure 2
Figure 2
Patient number versus (a) Mean dose difference for planning target volume using dose volume histogram analysis and (b) Gamma passing rates (3%/3 mm).
See this image and copyright information in PMC

References

    1. Thoelking J, Fleckenstein J, Sekar Y, et al. Patient‐specific online dose verification based on transmission detector measurements. Radiother Oncol. 2016;119(2):351–356. - PubMed
    1. Boggula R, Jahnke L, Wertz H, Lohr F, Wenz F. Patient‐specific 3D pretreatment and potential 3D online dose verification of Monte Carlo‐calculated IMRT prostate treatment plans. Int J Radiat Oncol Biol Phys. 2011;81(4):1168–1175. - PubMed
    1. Tamborra P, Martinucci E, Massafra R, et al. The 3D isodose structure‐based method for clinical dose distributions comparison in pretreatment patient‐QA. Med Phys. 2019;46(2):426–436. - PubMed
    1. Miften M, Olch A, Mihailidis D, et al. Tolerance limits and methodologies for IMRT measurement‐based verification QA: Recommendations of AAPM Task Group No. 218. Med Phys. 2018;45(4):e53–e83. - PubMed
    1. Ezzell GA, Galvin JM, Low D, et al. Guidance document on delivery, treatment planning, and clinical implementation of IMRT: report of the IMRT Subcommittee of the AAPM Radiation Therapy Committee. Med Phys. 2003;30(8):2089–2115. - PubMed

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