Radiotherapy & Oncology
Volume 94, Issue 2 , Pages 188-194, February 2010

3D dose delivery verification using repeated cone-beam imaging and EPID dosimetry for stereotactic body radiotherapy of non-small cell lung cancer

  • Wouter van Elmpt

      Affiliations

    • Corresponding Author InformationCorresponding author. Address: Department of Radiation Oncology (MAASTRO clinic), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Centre, Dr. Tanslaan 12, NL-6229 ET Maastricht, The Netherlands.
    • Both authors contributed equally to this work.
    • ,
  • Steven Petit

      Affiliations

    • Both authors contributed equally to this work.
    • ,
  • Dirk De Ruysscher
    • ,
  • Philippe Lambin
    • ,
  • André Dekker

Department of Radiation Oncology (MAASTRO), Maastricht University Medical Centre, The Netherlands

Received 19 October 2009; received in revised form 11 December 2009; accepted 20 December 2009. published online 18 January 2010.

Abstract 

Purpose

To implement a 3D dose verification procedure, based on in-room cone-beam CT imaging and portal dosimetry, for lung cancer patients treated with stereotactic body radiotherapy (SBRT).

Materials and methods

MV cone-beam CT scans were made for patient positioning and calibrated for dose calculation purposes. Prior to treatment, the treatment fields were captured using a calibrated electronic portal imaging device (EPID). A Monte Carlo dose reconstruction model was used to estimate the 3D dose delivered to the patient inside the cone-beam CT images. The planned and delivered dose distributions were compared for 4 patients and 10 treatment fractions using dose–volume histograms and gamma analysis.

Results

The gamma analysis showed a good agreement between the planned and delivered dose distributions for patients without changes in anatomy. The delivered mean dose per fraction inside the target volume deviated on average 1.1±1.4% from the planned dose. For the critical organs, only minor differences were observed between the reconstructed and planned dose.

Conclusions

A method was presented that allows verification of the dose delivered in 3D for lung cancer patients treated with SBRT. The procedure is independent of the treatment planning system and uses in-room MV cone-beam CT imaging and portal dosimetry.

Keywords: Dose reconstruction, Treatment verification, Cone-beam imaging, SBRT, Non-small cell lung cancer, Dose verification, Lung cancer

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PII: S0167-8140(09)00682-3

doi:10.1016/j.radonc.2009.12.024

Radiotherapy & Oncology
Volume 94, Issue 2 , Pages 188-194, February 2010

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