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Dosimetric comparison between the prostate intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans using the planning target volume (PTV) dose–volume factor

Published online by Cambridge University Press:  21 April 2016

James C. L. Chow*
Affiliation:
Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, ON Department of Radiation Oncology, University of Toronto, Toronto, ON
Runqing Jiang
Affiliation:
Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, Kitchener, ON Department of Physics and Astronomy, University of Waterloo, Waterloo, ON
Alexander Kiciak
Affiliation:
Department of Physics and Astronomy, University of Waterloo, Waterloo, ON
Daniel Markel
Affiliation:
Medical Physics Unit, University of McGill, Montreal, QC, Canada
*
Correspondence to: Dr James Chow. Radiation Medicine Program, Princess Margaret Cancer Center, University Health Network, 610 University Avenue, Toronto, ON, Canada M5G 2M9. Tel: 416 946 4501. Fax: 416 946 6566. E-mail: [email protected]

Abstract

Background

We demonstrated that our proposed planning target volume (PTV) dose–volume factor (PDVF) can be used to evaluate the PTV dose coverage between the intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans based on 90 prostate patients.

Purpose

PDVF were determined from the prostate IMRT and VMAT plans to compare their variation of PTV dose coverage. Comparisons of the PDVF with other plan evaluation parameters such as D5%, D95%, D99%, Dmean, conformity index (CI), homogeneity index (HI), gradient index (GI) and prostate tumour control probability (TCP) were carried out.

Methods and materials

Prostate IMRT and VMAT plans using the 6 MV photon beams were created from 40 and 50 patients, respectively. Dosimetric indices (CI, HI and GI), dose–volume points (D5%, D95%, D99% and Dmean) and prostate TCP were calculated according to the PTV dose–volume histograms (DVHs) of the plans. All PTV DVH curves were fitted using the Gaussian error function (GEF) model. The PDVF were calculated based on the GEF parameters.

Results

From the PTV DVHs of the prostate IMRT and VMAT plans, the average D99% of the PTV for IMRT and VMAT were 74·1 and 74·5 Gy, respectively. The average prostate TCP were 0·956 and 0·958 for the IMRT and VMAT plans, respectively. The average PDVF of the IMRT and VMAT plans were 0·970 and 0·983, respectively. Although both the IMRT and VMAT plans showed very similar prostate TCP, the dosimetric and radiobiological results of the VMAT technique were slightly better than IMRT.

Conclusion

The calculated PDVF for the prostate IMRT and VMAT plans agreed well with other dosimetric and radiobiological parameters in this study. PDVF was verified as an alternative of evaluation parameter in the quality assurance of prostate treatment planning.

Type
Original Articles
Copyright
© Cambridge University Press 2016 

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