Investigating output and energy variations and their relationship to delivery QA results using Statistical Process Control for helical tomotherapy


      • Correlation between machine TQA output and patient treatment QA.
      • Energy variation relationship between MVCT and ionisation chamber.
      • Statistical Process Control analysis of treatment beam parameters.


      The aims of this study were to investigate machine beam parameters using the TomoTherapy quality assurance (TQA) tool, establish a correlation to patient delivery quality assurance results and to evaluate the relationship between energy variations detected using different TQA modules. TQA daily measurement results from two treatment machines for periods of up to 4 years were acquired. Analyses of beam quality, helical and static output variations were made. Variations from planned dose were also analysed using Statistical Process Control (SPC) technique and their relationship to output trends were studied. Energy variations appeared to be one of the contributing factors to delivery output dose seen in the analysis. Ion chamber measurements were reliable indicators of energy and output variations and were linear with patient dose verifications.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Physica Medica: European Journal of Medical Physics
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Mackie T.R.
        • Balog J.
        • Ruchala K.
        • Shepard D.
        • Aldridge S.
        • Fitchard E.
        • et al.
        Semin Radiat Oncol: Elsevier. 1999; : 108-117
        • Klein E.E.
        • Hanley J.
        • Bayouth J.
        • Yin F.-F.
        • Simon W.
        • Dresser S.
        • et al.
        Task Group 142 report: Quality assurance of medical acceleratorsa).
        Med Phys. 2009; 36: 4197-4212
        • Meeks S.L.
        • Harmon Jr, J.F.
        • Langen K.M.
        • Willoughby T.R.
        • Wagner T.H.
        • Kupelian P.A.
        Performance characterization of megavoltage computed tomography imaging on a helical tomotherapy unit.
        Med Phys. 2005; 32: 2673-2681
        • Moutrie Z.R.
        • Lancaster C.M.
        • Yu L.
        First experiences in using a dose control system on a TomoTherapy Hi·Art II.
        J Appl Clin Med Phys. 2015; 16
        • Yang J.N.
        • Mackie T.R.
        • Reckwerdt P.
        • Deasy J.O.
        • Thomadsen B.R.
        An investigation of tomotherapy beam delivery.
        Med Phys. 1997; 24: 425-436
        • Balog J.
        • Mackie T.R.
        • Pearson D.
        • Hui S.
        • Paliwal B.
        • Jeraj R.
        Benchmarking beam alignment for a clinical helical tomotherapy device.
        Med Phys. 2003; 30: 1118-1127
        • Fenwick J.
        • Tome W.
        • Jaradat H.
        • Hui S.
        • James J.
        • Balog J.
        • et al.
        Quality assurance of a helical tomotherapy machine.
        Phys Med Biol. 2004; 49: 2933
        • Flynn R.
        • Kissick M.
        • Mehta M.
        • Olivera G.
        • Jeraj R.
        • Mackie T.
        The impact of linac output variations on dose distributions in helical tomotherapy.
        Phys Med Biol. 2007; 53: 417
        • Kissick M.W.
        • Fenwick J.
        • James J.A.
        • Jeraj R.
        • Kapatoes J.M.
        • Keller H.
        • et al.
        The helical tomotherapy thread effect.
        Med Phys. 2005; 32: 1414-1423
        • Binny D.
        • Lancaster C.M.
        • Harris S.
        • Sylvander S.R.
        Effects of changing modulation and pitch parameters on tomotherapy delivery quality assurance plans.
        J Appl Clin Med Phys. 2015; 16
        • Choi H.H.
        • Ho J.P.
        • Yang B.
        • Cheung K.Y.
        • Yu S.K.
        Technical note: Correlation between TQA data trends and TomoHD functional status.
        J Appl Clin Med Phys. 2014; 15
      1. Coevoet M, Denis J, Cravens B, Krumbach T, Figueredo J, Olivera G, et al. Tomotherapy quality assurance (TQA): a fast and comprehensive software tool. World Congress on Medical Physics and Biomedical Engineering, September 7–12, 2009, Munich, Germany: Springer; 2009. p. 678.

        • Balog J.
        • Olivera G.
        • Kapatoes J.
        Clinical helical tomotherapy commissioning dosimetry.
        Med Phys. 2003; 30: 3097-3106
        • Kirkup L.
        • Frenkel R.B.
        An introduction to uncertainty in measurement: using the GUM (guide to the expression of uncertainty in measurement).
        Cambridge University Press, 2006
        • Staton R.J.
        • Langen K.M.
        • Kupelian P.A.
        • Meeks S.L.
        Dosimetric effects of rotational output variation and x-ray target degradation on helical tomotherapy plans.
        Med Phys. 2009; 36: 2881-2888
        • Takahashi Y.
        • Hui S.K.
        Impact of very long time output variation in the treatment of total marrow irradiation with helical tomotherapy.
        Radiat Oncol. 2013; 8: 1
        • Broggi S.
        • Cattaneo G.M.
        • Molinelli S.
        • Maggiulli E.
        • Del Vecchio A.
        • Longobardi B.
        • et al.
        Results of a two-year quality control program for a helical tomotherapy unit.
        Radiother Oncol. 2008; 86: 231-241
        • Althof V.
        • van Haaren P.
        • Westendorp R.
        • Nuver T.
        • Kramer D.
        • Ikink M.
        • et al.
        A quality assurance tool for helical tomotherapy using a step-wedge phantom and the on-board MVCT detector.
        J Appl Clin Med Phys. 2012; 13
        • Hui S.K.
        • Kapatoes J.
        • Fowler J.
        • Henderson D.
        • Olivera G.
        • Manon R.R.
        • et al.
        Feasibility study of helical tomotherapy for total body or total marrow irradiation.
        Med Phys. 2005; 32: 3214-3224
        • Montgomery D.C.
        Statistical Quality Control.
        Wiley, New York2009
        • Boswell S.
        • Tomé W.
        • Jeraj R.
        • Jaradat H.
        • Mackie T.R.
        Automatic registration of megavoltage to kilovoltage CT images in helical tomotherapy: an evaluation of the setup verification process for the special case of a rigid head phantom.
        Med Phys. 2006; 33: 4395-4404
        • Langen K.M.
        • Papanikolaou N.
        • Balog J.
        • Crilly R.
        • Followill D.
        • Goddu S.M.
        • et al.
        QA for helical tomotherapy: Report of the AAPM Task Group 148a).
        Med Phys. 2010; 37: 4817-4853
      2. Millar M, Cramb J, Das R. ACPSEM Supplement. ACPSEM Position Paper: Recommendations for the Safe Use of External Beams and Sealed Brachytherapy Sources in Radiation Oncology. 1997.

      3. TomoTherapy Quality Assurance TQATM 107594 A ed: 2001–2012 Accuray Inc. p. 300.

        • Gérard K.
        • Grandhaye J.P.
        • Marchesi V.
        • Kafrouni H.
        • Husson F.
        • Aletti P.
        A comprehensive analysis of the IMRT dose delivery process using statistical process control (SPC).
        Med Phys. 2009; 36: 1275-1285
        • Pawlicki T.
        • Chera B.
        • Ning T.
        • Marks L.B.
        The systematic application of quality measures and process control in clinical radiation oncology.
        Semin Radiat Oncol: Elsevier. 2012; : 70-76
        • Pawlicki T.
        • Dunscombe P.B.
        • Mundt A.J.
        • Scalliet P.
        Quality and Safety in Radiotherapy.
        Taylor & Francis, 2010
        • Pawlicki T.
        • Whitaker M.
        • Boyer A.L.
        Statistical process control for radiotherapy quality assurance.
        Med Phys. 2005; 32: 2777-2786
        • Breen S.L.
        • Moseley D.J.
        • Zhang B.
        • Sharpe M.B.
        Statistical process control for IMRT dosimetric verification.
        Med Phys. 2008; 35: 4417-4425
        • Sanghangthum T.
        • Suriyapee S.
        • Srisatit S.
        • Pawlicki T.
        Retrospective analysis of linear accelerator output constancy checks using process control techniques.
        J Appl Clin Med Phys. 2013; 14: 147-160
        • Wheeler D.J.
        • Chambers D.S.
        Understanding Statistical Process Control.
        SPC press, 1992
        • Nelson L.S.
        The Anderson-Darling test for normality.
        J Qual Technol. 1998; 30: 298
        • Pettitt A.
        Testing the normality of several independent samples using the Anderson-Darling statistic.
        Appl Stat. 1977; 156–161
        • Binny D.
        • Lancaster C.M.
        • Kairn T.
        • Trapp J.V.
        • Crowe S.B.
        Monitoring Daily QA3 constancy for routine quality assurance on linear accelerators.
        Phys Med. 2016; 32: 1479-1489
        • Yu L.
        • Poole C.
        • Lancaster C.
        • Sylvander S.
        Towards online patient imaging during helical radiotherapy.
        Australas Phys Eng Sci Med. 2015; 38: 119-128