Treatment plan complexity metrics for predicting IMRT pre-treatment quality assurance results

  • S. B. CroweEmail author
  • T. Kairn
  • J. Kenny
  • R. T. Knight
  • B. Hill
  • C. M. Langton
  • J. V. Trapp
Scientific Paper


The planning of IMRT treatments requires a compromise between dose conformity (complexity) and deliverability. This study investigates established and novel treatment complexity metrics for 122 IMRT beams from prostate treatment plans. The Treatment and Dose Assessor software was used to extract the necessary data from exported treatment plan files and calculate the metrics. For most of the metrics, there was strong overlap between the calculated values for plans that passed and failed their quality assurance (QA) tests. However, statistically significant variation between plans that passed and failed QA measurements was found for the established modulation index and for a novel metric describing the proportion of small apertures in each beam. The ‘small aperture score’ provided threshold values which successfully distinguished deliverable treatment plans from plans that did not pass QA, with a low false negative rate.


Quality assurance Beam complexity Radiation therapy 


  1. 1.
    Purdy JA, Boyer AL, Butler EB, Dipetrillo TA, Engler MJ, Fraass B, Grant W III, Ling CC, Low DA, Mackie TR, Mohan R, Roach M, Rosenman JG, Verhey LJ, Wong JW, Cumberlin RL, Stone H, Palta JR (2001) Intensity-modulated radiotherapy: current status and issues of interest. Int J Radiat Oncol Biol Phys 51(4):880–914CrossRefGoogle Scholar
  2. 2.
    Lee MT, Purdie TG, Eccles CL, Sharpe MB, Dawson LA (2010) Comparison of simple and complex liver intensity modulated radiotherapy. Radiat Oncol 5:115PubMedCrossRefPubMedCentralGoogle Scholar
  3. 3.
    Nauta M, Villarreal-Barajas JE, Tambasco M (2011) Fractal analysis for assessing the level of modulation of IMRT fields. Med Phys 38(10):5385–5393PubMedCrossRefGoogle Scholar
  4. 4.
    Fenoglietto P, Laliberé B, Aillères N, Riou O, Dubois JB, Azria D (2011) Eight years of IMRT quality assurance with ionization chambers and film dosimetry: experience of the Montpellier Comprehensive Cancer Center. Radiat Oncol 6:85PubMedCrossRefPubMedCentralGoogle Scholar
  5. 5.
    McNiven AL, Sharpe MB, Purdie TG (2010) A new metric for assessing IMRT modulation complexity and plan deliverability. Med Phys 37(2):505–515PubMedCrossRefGoogle Scholar
  6. 6.
    Webb S (2003) Use of a quantitative index of beam modulation to characterize dose conformality: illustration by a comparison of full beamlet IMRT, few-segment IMRT (fsIMRT) and conformal unmodulated radiotherapy. Phys Med Biol 48(14):2051–2062PubMedCrossRefGoogle Scholar
  7. 7.
    Spirou SV, Chui CS (1998) A gradient inverse planning algorithm with dose-volume constraints. Med Phys 25(3):321–333PubMedCrossRefGoogle Scholar
  8. 8.
    Bortfeld T, Bürkelbach J, Boesecke R, Schlegel W (1990) Methods of image reconstruction from projections applied to conformation radiotherapy. Phys Med Biol 35(10):1423–1434PubMedCrossRefGoogle Scholar
  9. 9.
    Llacer J, Solberg TD, Promberger C (2001) Comparative behaviour of the dynamically penalized likelihood algorithm in inverse radiation therapy planning. Phys Med Biol 46(10):2637–2663PubMedCrossRefGoogle Scholar
  10. 10.
    McGarry CK, Chinneck CD, O’Toole MM, O’Sullivan JM, Prise KM, Hounsell AR (2011) Assessing software upgrades, plan properties and patient geometry using intensity modulated radiation therapy (IMRT) complexity metrics. Med Phys 38(4):2027–2034PubMedCrossRefGoogle Scholar
  11. 11.
    Nicolini G, Fogliata A, Vanetti E, Clivio A, Ammazzalorso F, Cozzi L (2007) What is an acceptably smoothed fluence? Dosimetric and delivery considerations for dynamic sliding window IMRT. Radiat Oncol 2:42CrossRefGoogle Scholar
  12. 12.
    Kim T, Zhu L, Suh T-S, Geneser S, Meng B, Xing L (2011) Inverse planning for IMRT with nonuniform beam profiles using total-variation regularization (TVR). Med Phys 38(1):57–66PubMedCrossRefPubMedCentralGoogle Scholar
  13. 13.
    Tonigan J, Kry S, Dong L, Purdie T, White R, Ibbott G, Followill D (2011) Does IMRT treatment plan complexity or mismatched dosimetry data contribute to dose delivery errors detected using an IMRT H&N quality assurance phantom? Med Phys 38(6):3804CrossRefGoogle Scholar
  14. 14.
    Tonigan JR (2011) Evaluation of intensity modulated radiation therapy (IMRT) delivery error due to IMRT treatment plan complexity and improperly matched dosimetry data. Master’s Thesis, University of TexasGoogle Scholar
  15. 15.
    Kairn T, Hardcastle N, Kenny J, Meldrum R, Tomé WA, Aland T (2011) EBT2 radiochromic film for quality assurance of complex IMRT treatments of the prostate: micro-collimated IMRT, RapidArc, and TomoTherapy. Australas Phys Eng Sci Med 34(3):333–343PubMedCrossRefGoogle Scholar
  16. 16.
    Kairn T, Crowe S, Kenny J, Trapp JV (2011) Investigation of stereotactic radiotherapy dose using dosimetry film and Monte Carlo simulations. Radiat Meas 46(12):1985–1988CrossRefGoogle Scholar
  17. 17.
    Ahnesjö A, Aspradakis MM (1999) Dose calculations for external photon beams in radiotherapy. Phys Med Biol 44(11):R99–R155PubMedCrossRefGoogle Scholar
  18. 18.
    Brainlab AG (2010) Brainlab physics technical reference guide. Revision 1:2Google Scholar
  19. 19.
    Crowe S, Kairn T, Fielding AL (2009) The development of a Monte Carlo system to verify radiotherapy treatment dose calculations. Radiother Oncol 92(Supp 1):S71CrossRefGoogle Scholar
  20. 20.
    Crowe SB, Kairn T, Trapp JV, Fielding AL (2013) Experimental evaluation of MCDTK, the Monte Carlo DICOM ToolKit. IFMBE Proc 39:1807–1810CrossRefGoogle Scholar
  21. 21.
    Crowe SB, Kairn T, Middlebrook N, Bill B, Christie DRH, Knight RT, Kenny J, Langton CM, Trapp JV (2013) Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity-modulated and volumetric-modulated arc radiotherapy. J Med Radiat Sci 60(4):131–138CrossRefGoogle Scholar
  22. 22.
    Arnfield MR, Siebers JV, Kim JO, Wu Q, Keall PJ, Mohan R (2000) A method for determining multileaf collimator transmission and scatter for dynamic intensity modulated radiotherapy. Med Phys 27(10):2231–2241PubMedCrossRefGoogle Scholar
  23. 23.
    Cosgrove VP, Jahn U, Pfaender M, Bauer S, Budach V, Wurm RE (1999) Commissioning of a micro multi-leaf collimator and planning system for stereotactic radiosurgery. Radiother Oncol 50(3):325–336PubMedCrossRefGoogle Scholar
  24. 24.
    Nicolini G, Vanetti E, Clivio A, Fogliata A, Korreman S, Bocanek J, Cozzi L (2008) The GLAaS algorithm for portal dosimetry and quality assurance of RapidArc, an intensity modulated rotational therapy. Radiat Oncol 3:24PubMedCrossRefPubMedCentralGoogle Scholar

Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2014

Authors and Affiliations

  • S. B. Crowe
    • 1
    Email author
  • T. Kairn
    • 1
    • 2
  • J. Kenny
    • 3
  • R. T. Knight
    • 2
  • B. Hill
    • 2
  • C. M. Langton
    • 1
  • J. V. Trapp
    • 1
  1. 1.Science and Engineering FacultyQueensland University of TechnologyBrisbaneAustralia
  2. 2.Genesis Cancer Care QueenslandBrisbaneAustralia
  3. 3.Epworth Radiation OncologyMelbourneAustralia

Personalised recommendations