Document Type : Original Paper
Authors
1
Department of physics, Faculty of sciences, University Mohammed V in Rabat, Morocco
2
Mohammed VI University of Health Sciences, Casablanca, Morocco
3
Iba Dosimetry Schwarzenbruck, Germany
4
Faculty of Sciences, LPHE-M&S, Mohammed V University, Rabat
5
Université Mohammed V de Rabat
6
Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
7
Departement of Physics, Laboratory of High Energy Physics, Modelling and Simulation, Faculty of Science, Mohammed V Agdal University, Rabat, Kingdom of Morocco
8
1Department of physics, Faculty of sciences, University Mohammed V in Rabat, Morocco
Abstract
Background: treatment of pelvic bone metastases using Halcyon machine, mostly present some difficulties to plan, especially for big volumes because of the machine field size. The purpose of this study was to evaluate the advantages of the proposed technique in overcoming the limitations of the Halcyon machine and achieving clinically satisfactory results.
Methods: We report a retrospective study of 8 patients who received radiotherapy for pelvic bone metastases, all treated by two different VMAT techniques. The first technique was performed by two longitudinal isocenters (loIT) and the second by two lateral isocenters respecting the authorized distance longitudinally between two isocenters which must be less than 8 cm. For each isocenter, two opposite arcs are used for all treated patients.
Results: Plans conformity index (CI) assessment shows no difference between the two used techniques for all the treated patients. Remarkable coverage of PTVs was obtained in laIT with 96.2% compared to 94%.6% for loIT, as well as the maximum dose which was 109.4% for laIT versus 112.3% for loIT. The benefit of the laIT was greater for patients with big size of pelvis. Conformation number that takes into account for both healthy tissue and organ at risk protection was improved with 7.3% by using laIT.
Conclusion: A very satisfactory result has been obtained in the treatment of pelvic bone metastases with laIT. With this technique, we can exceed the limits of the Halcyon machine and process larger volumes.
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