CT-based dose recalculations in head and neck cancer radiotherapy: comparison of daily dose recalculations to less time-consuming approaches

  • Simon Wagenblast
  • Severin Kampfer
  • Kai J. Borm
  • Stephanie E. Combs
  • Steffi U. Pigorsch
  • Marciana-Nona DumaEmail author
Original Article



The goal of this study was to investigate if daily dose recalculations are necessary or if less time-consuming approaches can be used to identify dose differences to the planned dose in patients with head and neck cancers (H&N).


For 12 H&N patients treated with helical tomotherapy, daily dose calculations were performed retrospectively. Four different summation doses (SuDo) were calculated: DayDo (daily dose calculation), MVCTx2, MVCTx5, and MVCTx10 (dose calculations every second, fifth, and tenth fraction). Dose recalculations were depicted on the last contoured mega voltage CT (MVCT). The DayDo was compared to the planned dose and to the less time-consuming SuDo scenarios. The doses were assessed for the planning target volume (PTV) and the organs at risk (OARs): mandible (mand), spinal cord (SC), spinal cord +5 mm (SC+5 mm), parotid glands (PG).


The ipsilateral PG, contralateral PG, and PTV volume decreased by −22.5% (range: −34.8 to 5.2%), −19.5% (−31.5 to 15.8%), and −2.6% (−16.7 to 0.2%), respectively. There was a significant median mean dose (Dmean) dose difference for DayDo compared to the planned dose for PG total of 1.9 Gy (−3.3 to 7.3 Gy). But less time-consuming SuDo compared to DayDo showed statistically significant but not clinically relevant (<2%) dose differences for several organs. Hence the small dose difference to the gold standard (DayDo), we recommend dose recalculations every fifth MVCT in order to identify the occurrence of dose differences compared to the planned dose.


Daily dose calculations are the most precise to assess dose differences between actual and planned dose. Dose recalculations on every fifth MVCT (i. e., weekly control CTs) are an applicable and time-saving way of identifying patients with significant dose differences compared to the planned dose.


MVCT cancers Adaptive radiotherapy Helical tomotherapy IGRT IMRT 

CT-basierte Dosisneuberechnung bei der Strahlentherapie von Kopf-Hals-Tumoren: Vergleich der täglichen Dosisneuberechnung mit weniger zeitaufwändigen Ansätzen



Ziel dieser Studie war es, zu untersuchen, ob die tägliche Dosisneuberechnung (DayDo) nötig ist und ob weniger zeitaufwendige Dosisberechnungen geeignet sind, um Dosisunterschiede bei der Planungsdosis von Patienten mit Kopf-Hals-Tumoren (H&N) zu identifizieren.


Insgesamt 12 H&N-Patienten wurden mittels Tomotherapie bestrahlt und tägliche Dosisberechnungen wurden retrospektiv durchgeführt. Es wurden 4 verschiedene Szenarien (SuDo) berechnet: DayDo (tägliche Dosisberechnung), MVCTx2, MVCTx5 und MVCTx10 (Dosisberechnungen jede zweite, fünfte und zehnte Fraktion). Die Dosis-Neuberechnungen wurden auf dem letzten MVCT dargestellt. Die tägliche Dosisberechnung wurde mit der Planungsdosis und den weniger zeitaufwendigen Szenarien verglichen. Des Weiteren wurden die Volumenveränderungen im Verlauf der Strahlentherapie erfasst. Bestimmt wurden die Dosen für das Zielvolumen (PTV) und für die Risikoorgane (OARs): Unterkiefer (mand), Rückenmark (SC), Rückenmark +5 mm (SC+5 mm) und Ohrspeicheldrüsen (PG).


Das Volumen der ipsi- und kontralateralen PG sowie das PTV sanken um −22,5 % (Spanne −34,8–5,2 %), −19,5 % (Spanne −31,5–15,8 %) bzw. −2,6 % (Spanne −16,7–0,2 %). Es gab eine statistisch signifikante Dosisdifferenz der medianen Dmean beider PG zusammen um 1,9 Gy (Spanne −3,3–7,3 Gy). Für verschiedene OARs existierten für die weniger zeitaufwändigen Szenarien im Vergleich zur DayDo zwar statistisch signifikante, aber klinisch nicht relevante Dosisunterschiede (<2 %). Aufgrund der klinisch irrelevanten Unterschiede sind Dosisberechnungen jedes fünften MVCT ein einfaches und zeitsparendes Verfahren, um Dosisunterschiede zwischen Planungsdosis und wirklicher Dosis festzustellen.


Tägliche Dosisneuberechnung ist die genaueste Methode, um Dosisunterschiede zwischen Planung und tatsächlicher Dosis zu ermitteln. Aber Dosisberechnung jedes fünften MVCT ist ein zeitsparendes und einfaches Verfahren, um Dosisunterschiede zwischen Planungsdosis und wirklicher Dosis festzustellen.


Kopf- und Halstumore Adaptive Strahlentherapie Helikale Tomotherapie IGRT IMRT 


Conflict of interest

S. Kampfer received 2015 a professional fee from Accuray. S. Wagenblast, K.J. Borm, S.E. Combs, S.U. Pigorsch, and M.-N. Duma declare that they have no competing interests.


  1. 1.
    Cozzi L et al (2004) Three-dimensional conformal vs. intensity-modulated radiotherapy in head-and-neck cancer patients: comparative analysis of dosimetric and technical parameters. Int J Radiat Oncol Biol Phys 58(2):617–624CrossRefPubMedGoogle Scholar
  2. 2.
    Fiorino C et al (2006) Significant improvement in normal tissue sparing and target coverage for head and neck cancer by means of helical tomotherapy. Radiother Oncol 78(3):276–282CrossRefPubMedGoogle Scholar
  3. 3.
    Galvin JM, De Neve W (2007) Intensity modulating and other radiation therapy devices for dose painting. J Clin Oncol 25(8):924–930CrossRefPubMedGoogle Scholar
  4. 4.
    Sheng K et al (2008) Is daily CT image guidance necessary for nasal cavity and nasopharyngeal radiotherapy: an investigation based on helical tomotherapy. J Appl Clin Med Phys 9(1):2686CrossRefPubMedGoogle Scholar
  5. 5.
    Sheng K, Molloy JA, Read PW (2006) Intensity-modulated radiation therapy (IMRT) dosimetry of the head and neck: a comparison of treatment plans using linear accelerator-based IMRT and helical tomotherapy. Int J Radiat Oncol Biol Phys 65(3):917–923CrossRefPubMedGoogle Scholar
  6. 6.
    Lee C et al (2008) Evaluation of geometric changes of parotid glands during head and neck cancer radiotherapy using daily MVCT and automatic deformable registration. Radiother Oncol 89(1):81–88CrossRefPubMedGoogle Scholar
  7. 7.
    Lu J et al (2014) Assessment of anatomical and dosimetric changes by a deformable registration method during the course of intensity-modulated radiotherapy for nasopharyngeal carcinoma. J Radiat Res 55(1):97–104CrossRefPubMedGoogle Scholar
  8. 8.
    Ahn PH et al (2011) Adaptive planning in intensity-modulated radiation therapy for head and neck cancers: single-institution experience and clinical implications. Int J Radiat Oncol Biol Phys 80(3):677–685CrossRefPubMedGoogle Scholar
  9. 9.
    Ballivy O et al (2006) Impact of geometric uncertainties on dose distribution during intensity modulated radiotherapy of head-and-neck cancer: the need for a planning target volume and a planning organ-at-risk volume. Curr Oncol 13(3):108–115PubMedPubMedCentralGoogle Scholar
  10. 10.
    Bhide SA et al (2010) Weekly volume and dosimetric changes during chemoradiotherapy with intensity-modulated radiation therapy for head and neck cancer: a prospective observational study. Int J Radiat Oncol Biol Phys 76(5):1360–1368CrossRefPubMedGoogle Scholar
  11. 11.
    Duma MN et al (2012) Adaptive radiotherapy for soft tissue changes during helical tomotherapy for head and neck cancer. Strahlenther Onkol 188(3):243–247CrossRefPubMedGoogle Scholar
  12. 12.
    Ahn PH et al (2009) Random positional variation among the skull, mandible, and cervical spine with treatment progression during head-and-neck radiotherapy. Int J Radiat Oncol Biol Phys 73(2):626–633CrossRefPubMedGoogle Scholar
  13. 13.
    Castelli J et al (2015) Impact of head and neck cancer adaptive radiotherapy to spare the parotid glands and decrease the risk of xerostomia. Radiat Oncol 10(1):6CrossRefPubMedPubMedCentralGoogle Scholar
  14. 14.
    Deng S et al (2017) Three-phase adaptive radiation therapy for patients with nasopharyngeal carcinoma undergoing intensity-modulated radiation therapy: dosimetric analysis. Technol Cancer Res Treat. CrossRefPubMedPubMedCentralGoogle Scholar
  15. 15.
    Fung WW, Wu VW, Teo PM (2012) Dosimetric evaluation of a three-phase adaptive radiotherapy for nasopharyngeal carcinoma using helical tomotherapy. Med Dosim 37(1):92–97CrossRefPubMedGoogle Scholar
  16. 16.
    Budach W et al (2011) Evaluation of time, attendance of medical staff, and resources during radiotherapy for head and neck cancer patients: the DEGRO-QUIRO trial. Strahlenther Onkol 187(8):449–460CrossRefPubMedGoogle Scholar
  17. 17.
    Ho KF et al (2012) Monitoring dosimetric impact of weight loss with kilovoltage (kV) cone beam CT (CBCT) during parotid-sparing IMRT and concurrent chemotherapy. Int J Radiat Oncol Biol Phys 82(3):e375–e382CrossRefPubMedGoogle Scholar
  18. 18.
    Hunter KU et al (2013) Parotid glands dose-effect relationships based on their actually delivered doses: implications for adaptive replanning in radiation therapy of head-and-neck cancer. Int J Radiat Oncol Biol Phys 87(4):676–682CrossRefPubMedPubMedCentralGoogle Scholar
  19. 19.
    Nishi T et al (2013) Volume and dosimetric changes and initial clinical experience of a two-step adaptive intensity modulated radiation therapy (IMRT) scheme for head and neck cancer. Radiother Oncol 106(1):85–89CrossRefPubMedGoogle Scholar
  20. 20.
    Gregoire V et al (2006) Proposal for the delineation of the nodal CTV in the node-positive and the post-operative neck. Radiother Oncol 79(1):15–20CrossRefPubMedGoogle Scholar
  21. 21.
    Gregoire V et al (2014) Delineation of the neck node levels for head and neck tumors: a 2013 update. DAHANCA, EORTC, HKNPCSG, NCIC CTG, NCRI, RTOG, TROG consensus guidelines. Radiother Oncol 110(1):172–181CrossRefPubMedGoogle Scholar
  22. 22.
    Yadav P et al (2010) The effect and stability of MVCT images on adaptive TomoTherapy. J Appl Clin Med Phys 11(4):3229CrossRefPubMedGoogle Scholar
  23. 23.
    Langen KM et al (2005) The use of megavoltage CT (MVCT) images for dose recomputations. Phys Med Biol 50(18):4259–4276CrossRefPubMedGoogle Scholar
  24. 24.
    Hansen EK et al (2006) Repeat CT imaging and replanning during the course of IMRT for head-and-neck cancer. Int J Radiat Oncol Biol Phys 64(2):355–362CrossRefPubMedGoogle Scholar
  25. 25.
    Barker JL Jr. et al (2004) Quantification of volumetric and geometric changes occurring during fractionated radiotherapy for head-and-neck cancer using an integrated CT/linear accelerator system. Int J Radiat Oncol Biol Phys 59(4):960–970CrossRefPubMedGoogle Scholar
  26. 26.
    Beltran M et al (2012) Dose variations in tumor volumes and organs at risk during IMRT for head-and-neck cancer. J Appl Clin Med Phys 13(6):3723CrossRefPubMedGoogle Scholar
  27. 27.
    Ajani AA et al (2013) A quantitative assessment of volumetric and anatomic changes of the parotid gland during intensity-modulated radiotherapy for head and neck cancer using serial computed tomography. Med Dosim 38(3):238–242CrossRefPubMedGoogle Scholar
  28. 28.
    Hermans BC et al (2015) Weekly kilovoltage cone-beam computed tomography for detection of dose discrepancies during (chemo)radiotherapy for head and neck cancer. Acta Oncol 54(9):1483–1489CrossRefPubMedGoogle Scholar
  29. 29.
    Yip C et al (2014) Co-registration of cone beam CT and planning CT in head and neck IMRT dose estimation: a feasible adaptive radiotherapy strategy. Br J Radiol 87(1034):20130532CrossRefPubMedPubMedCentralGoogle Scholar
  30. 30.
    Schwartz DL et al (2012) Adaptive radiotherapy for head-and-neck cancer: initial clinical outcomes from a prospective trial. Int J Radiat Oncol Biol Phys 83(3):986–993CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Radiation Oncology, Klinikum rechts der IsarTechnical University MunichMunichGermany
  2. 2.Faculty of MedicineTechnical UniversityMunichGermany
  3. 3.Deutsches Konsortium für Translationale Krebsforschung (DKTK)-Partner Site MunichMunichGermany
  4. 4.Institute of Innovative RadiotherapyHelmholtzzentrum MünchenMunichGermany

Personalised recommendations