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Evaluation of PTV margins in IMRT for head and neck cancer and prostate cancer

Published online by Cambridge University Press:  17 February 2020

M. A. Youssoufi ,
M. Bougtib ,
S. Douama ,
M. Ait Erraisse ,
F. Z. Abboud ,
K. Hassouni  and
F. Bentayeb Open the ORCID record for F. Bentayeb [Opens in a new window]
M. A. Youssoufi
Affiliation:
Faculty of Sciences (LPHE, M-S), University Mohammed V, Rabat, Morocco Department of Radiotherapy, University Hospital Hassan II, Fes, Morocco
M. Bougtib
Affiliation:
Faculty of Sciences (LPHE, M-S), University Mohammed V, Rabat, Morocco Department of Radiotherapy, University Hospital Hassan II, Fes, Morocco
S. Douama
Affiliation:
Faculty of Sciences (LPHE, M-S), University Mohammed V, Rabat, Morocco
M. Ait Erraisse
Affiliation:
Department of Radiotherapy, University Hospital Hassan II, Fes, Morocco
F. Z. Abboud
Affiliation:
Department of Radiotherapy, University Hospital Hassan II, Fes, Morocco
K. Hassouni
Affiliation:
Department of Radiotherapy, University Hospital Hassan II, Fes, Morocco
F. Bentayeb*
Affiliation:
Faculty of Sciences (LPHE, M-S), University Mohammed V, Rabat, Morocco
*
Author for correspondence: F. Bentayeb, Department of Physics, Faculty of Sciences, B.P. 1014, 10000Rabat, Morocco. Tel: +00212 668460012. E-mail: [email protected]
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Abstract

Purpose:

The aim of this study was to evaluate planning target volume (PTV) margins for two different locations using an electronic portal imaging device (EPID) to ensure that the correct radiation dose is delivered to the tumour when using intensity-modulated radiation therapy (IMRT).

Materials and methods:

Setup data were collected from 40 patients treated with IMRT for head and neck cancer (HN) (20 patients) and prostate cancer (20 patients). Setup errors from 720 registration images were analysed to evaluate systematic and random errors. Thereafter, optimal PTV margins were calculated based on International Commission on Radiation Units and Measurements 62 (ICRU), Stroom and Parker formulas compared with the Van Herk’s recipe.

Results:

To calculate the margins around the PTV, several different formulas have been used. Setup margins ranged between 2–4·3, 2·2–4·6 and 2·1–4·7 mm in X, Y and Z directions, respectively, for HN cases. Similarly, for the prostate site, setup margins ranged between 3·7–8·3, 3·2–6·8 and 3·3–8·2 mm in X, Y and Z directions.

Conclusion:

To ensure better coverage of target volume, we adopted a PTV margin of 5 mm for HN PTVs and 10 mm for prostate PTVs in our department.

Keywords

electronic portal imaging devicehead and neckplanning target volumeprostate
Type
Technical Note
Information
Journal of Radiotherapy in Practice , Volume 20 , Issue 1 , March 2021 , pp. 114 - 119
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Copyright
© The Author(s), 2020. Published by Cambridge University Press

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