Characterization of EPID software for VMAT transit dosimetry

  • Marco EspositoEmail author
  • Andrea Bruschi
  • Paolo Bastiani
  • Alessandro Ghirelli
  • Silvia Pini
  • Serenella Russo
  • Giovanna Zatelli
Technical Paper


Dosimetry check (DC) is a commercial software that allows reconstruction of 3D dose distributions using transit electronic portal imaging device (EPID) images. In this work, we evaluated the suitability of DC software for volumetric modulated arc therapy (VMAT) transit dosimetry. The volumetric gamma agreement index 3%/3 mm between twenty VMAT dose distributions reconstructed by DC and calculated with treatment planning system (TPS) were compared to those obtained using PTW OCTAVIUS®4D to assess DC accuracy in VMAT quality assurance (QA). The sensitivity of DC in detecting VMAT delivery and set-up errors and anatomical variations has been investigated by measuring the variation of the gamma agreement index before and after the introduction of specific errors in four VMAT plans related to different anatomical sites. The influence of dose computation algorithm in presence of density inhomogeneity was also assessed. The assessment of VMAT QA shows agreements with TPS maps comparable to OCTAVIUS® 4D (OCT) in homogeneous phantom (p < 0.001). DC mean gamma agreement index was 94.2% ± 3.4, versus 95.6% ± 2.5 of OCT, lower dose threshold was set to 10%. Introduction of deliberate errors resulted in lower gamma agreement index and in 38/56 cases the gamma agreement index was over the detection threshold. The dose computation algorithm of DC is accurate in all anatomical sites except lung. However in lung cases, the aqua vivo approach used in this work reduced the algorithm dependence of DC results. DC accurately reproduced VMAT 3D dose distributions in phantom and is sensitive to detect errors caused by delivery inaccuracy and anatomical variations of patients.


VMAT In vivo dosimetry EPID 


Compliance with ethical standards

Conflict of interest

The authors have no relevant conflicts of interest to disclose.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Supplementary material

13246_2018_693_MOESM1_ESM.doc (205 kb)
Supplementary material 1 (DOC 205 KB)


  1. 1.
    Bedford JL, Warrington AP (2009) Commissioning of volumetric modulated arc therapy (VMAT). Int J Radiat Oncol Biol Phys 73(2):537–545CrossRefGoogle Scholar
  2. 2.
    Ezzell GA, Galvin JM, Low D, Palta JR, Rosen I, Sharpe MB et al (2003) Guidance document on delivery, treatment planning, and clinical implementation of IMRT: report of the IMRT Subcommittee of the AAPM Radiation Therapy Committee. Med Phys 30(8):2089–2115CrossRefGoogle Scholar
  3. 3.
    Otto K (2008) Volumetric modulated arc therapy: IMRT in a single arc. Med Phys 35:310–317CrossRefGoogle Scholar
  4. 4.
    Bedford JL, Lee YK, Wai P, South CP, Warrington AP (2009) Evaluation of the Delta4 phantom for IMRT and VMAT verification. Phys Med Biol 54(9):N167–N176CrossRefGoogle Scholar
  5. 5.
    Stathakis S, Myers P, Esquivel C, Mavroidis P, Papanikolaou N (2013) Characterization of a novel 2D array dosimeter for patient-specific quality assurance with volumetric arc therapy. Med Phys 40(7):071731CrossRefGoogle Scholar
  6. 6.
    Li G, Zhang Y, Jiang X, Bai S, Peng G, Wu K, Jiang Q (2013) Evaluation of the ArcCHECK QA system for IMRT and VMAT verification. Phys Med 29(3):295–303CrossRefGoogle Scholar
  7. 7.
    Boggula R, Lorenz F, Mueller L, Birkner M, Wertz H, Stieler F, Wenz F (2010) Experimental validation of a commercial 3D dose verification system for intensity-modulated arc therapies. Phys Med Biol 55(19):5619–5633CrossRefGoogle Scholar
  8. 8.
    Van Esch A, Basta K, Evrard M, Ghislain M, Sergent F, Huyskens DP (2014) The Octavius1500 2D ion chamber array and its associated phantoms: dosimetric characterization of a new prototype. Med Phys 41(9):091708CrossRefGoogle Scholar
  9. 9.
    McGarry CK, O’Connell BF, Grattan MW, Agnew CE, Irvine DM, Hounsell AR (2013) Octavius 4D characterization for flattened and flattening filter free rotational deliveries. Med Phys 40(9):091707CrossRefGoogle Scholar
  10. 10.
    Fredh A, Scherman JB, Fog LS, af Rosenschöld PM (2013) Patient QA systems for rotational radiation therapy: a comparative experimental study with intentional errors. Med Phys 40(3):031716CrossRefGoogle Scholar
  11. 11.
    Zhen H, Nelms BE, Tomé WA (2011) Moving from gamma passing rates to patient DVH-based QA metrics in pretreatment dose QA. Med Phys 38(10):5477–5489CrossRefGoogle Scholar
  12. 12.
    Nelms BE, Chan MF, Jarry G, Lemire M, Lowden J, Hampton C, Feygelman V (2013) Practical examples of failure to detect systematic errors when applying a commonly used metric and action levels. Med Phys 40(11):111722CrossRefGoogle Scholar
  13. 13.
    Bojechko C, Phillps M, Kalet A, Ford EC (2015) A quantification of the effectiveness of EPID dosimetry and software-based plan verification systems in detecting incidents in radiotherapy. Med Phys 42(9):5363:5369CrossRefGoogle Scholar
  14. 14.
    Mans A, Remeijer P, Olaciregui-Ruiz I, Wendling M, Sonke JJ, Mijnheer B et al (2010) 3D Dosimetric verification of volumetric-modulated arc therapy by portal dosimetry. Radiother Oncol 94(2):181–187CrossRefGoogle Scholar
  15. 15.
    Greer PB (2013) 3D EPID based dosimetry for pre-treatment verification of VMAT-methods and challenges. J Phys: Conf Ser 444:012010Google Scholar
  16. 16.
    Fogliata A, Clivio A, Fenoglietto P, Hrbaeck J, Kloeck S, Lattauda P et al (2011) Quality assurance of RapidArc in clinical practice using portal dosimetry. Br J Radiol 84:534–545CrossRefGoogle Scholar
  17. 17.
    Chaumet F, Bleuse O (2013) Implementation of in vivo dosimetry with epigray. Phys Med 29:e32CrossRefGoogle Scholar
  18. 18.
    Fidanzio A, Cilla S, Greco F, Gargiulo L, Azario L, Sabatino D et al (2011) Generalized EPID calibration for in vivo transit dosimetry. Phys Med 27(1):30–38CrossRefGoogle Scholar
  19. 19.
    Ricketts K, Navarro C, Lane K, Moran M, Blowfield C, Kaur U et al (2016) Implementation and evaluation of a transit dosimetry system for treatment verification. Phys Med 32(5):671–680CrossRefGoogle Scholar
  20. 20.
    Renner WD, Nortono KJ, Holmes TW (2005) A method for deconvolution of integrated electronic portal images to obtain fluence for dose reconstruction. J Appl Clin Med Phys. 6(4):22–39CrossRefGoogle Scholar
  21. 21.
    Renner WD, Sarfaraz M, Earl MA, Yu CX (2003) A dose delivery verification method for conventional and intensity-modulated radiation therapy using measured field fluence distributions. Med Phys 30(11):2996–3005CrossRefGoogle Scholar
  22. 22.
    Narayanasamy G, Zalman T, Ha CS, Papanikolaou N, Stathakis S (2015) Evaluation of Dosimetry Check software for IMRT patient-specific quality assurance. J Appl Clin Med Phys 16(3):329–338CrossRefGoogle Scholar
  23. 23.
    Gimeno J, Pujades MC, García T, Carmona V, Lliso F, Palomo R et al (2014) Commissioning and initial experience with a commercial software for in vivo volumetric dosimetry. Phys Med 30(8):954–959CrossRefGoogle Scholar
  24. 24.
    Ezzell GA, Burmeister JW, Dogan N, LoSasso TJ, Mechalakos JG, Mihailidis D et al (2009) IMRT commissioning: multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Med Phys 36:5359CrossRefGoogle Scholar
  25. 25.
    Wendling M, McDermott LM, Mans A, Olaciregui-Ruiz I, Pecharromán-Gallego R, Sonke JJ et al (2012) In aqua vivo EPID. dosimetry. Med Phys 39(1):367–377CrossRefGoogle Scholar
  26. 26.
    Vieillevigne L, Molinier J, Brun T, Ferrand R (2015) Gamma index comparison of three VMAT QA systems and evaluation of their sensitivity to delivery errors. Phys Med 31(7):720–725CrossRefGoogle Scholar
  27. 27.
    Bruschi A, Esposito M, Pini S, Ghirelli A, Zatelli G, Russo S (2018) How the detector resolution affects the clinical significance of SBRT pre-treatment quality assurance results. Phys Med. CrossRefPubMedGoogle Scholar
  28. 28.
    Van Dyk J, Barnett RB, Cygler JE, Shragge PC (1993) Commissioning and quality assurance of treatment planning computers. Int J Radiat Oncol Biol Phys 26:261–273CrossRefGoogle Scholar
  29. 29.
    Nelms BE, Zhen H, Tomé WA (2011) Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors. Med Phys 38(2):1037–1044CrossRefGoogle Scholar
  30. 30.
    Stasi M, Bresciani S, Miranti A, Maggio A, Sapino V, Gabriele P (2012) Pretreatment patient-specific IMRT quality assurance: a correlation study between gamma index and patient clinical dose volume histogram. Med Phys 39(12):7626–7634CrossRefGoogle Scholar
  31. 31.
    McCowan PM, Asuni G, Van Uytven E, VanBeek T, McCurdy B et al (2017) Clinical implementation of a model-based in vivo dose verification system for stereotactic body radiation therapye volumetric modulated arc therapy treatments using the electronic portal imaging device. Int J Radiat Oncol Biol Phys 97(5):1077–1084CrossRefGoogle Scholar
  32. 32.
    Linthout N, Verellen D, Tournel K, Storme G (2006) Six dimensional analysis with daily stereoscopic X-ray imaging of intrafraction patient motion in head and neck treatments using five points fixation masks. Med Phys 33(2):504–513CrossRefGoogle Scholar
  33. 33.
    Shelton J, Rossi PJ, Chen H, Liu Y, Master VA, Jani AB (2011) Observations on prostate intrafraction motion and the effect of reduced treatment time using volumetric modulated arc therapy. Pract Radiat Oncol 1(4):243–250CrossRefGoogle Scholar
  34. 34.
    Kearney V, Solberg T, Jensen S, Cheung J, Chuang C, Valdes G (2018) Correcting TG 119 confidence limits. Med Phys 45(3):1001–1008CrossRefGoogle Scholar
  35. 35.
    Vikraman S, Manigandan D, Karrthick KP, Sambasivaselli R, Senniandavar V, Ramu M et al (2014) Quantitative evaluation of 3D dosimetry for stereotactic volumetric-modulated arc delivery using COMPASS. J Appl Clin Med Phys 16(1):5128PubMedGoogle Scholar
  36. 36.
    Tyagi N, Yang K, Yan D (2015) Comparing measurement-derived (3DVH) and machine log file-derived dose reconstruction methods for VMAT QA in patient geometries J Appl Clin Med Phys 15(4):464Google Scholar
  37. 37.
    Woodruff HC, Fuangrod T, Van Uytven E, McCurdy BM, van Beek T, Bhatia S et al (2015) First experience with real-time EPID-based delivery verification during IMRT and VMAT sessions. Int J Radiat Oncol Biol Phys 93(3):516–522CrossRefGoogle Scholar
  38. 38.
    Thoelking J, Fleckenstein J, Sekar Y, Boggula R, Lohr F et al (2016) Patient-specific online dose verification based on transmission detector measurements. Radiother Oncol 119(2):351–356CrossRefGoogle Scholar

Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2018

Authors and Affiliations

  1. 1.S.C. Fisica Sanitaria Azienda USL Toscana CentroFirenzeItaly
  2. 2.S.C. Radioterapia Azienda USL Toscana CentroFirenzeItaly
  3. 3.Casa di cura San RossorePisaItaly

Personalised recommendations