open access

Vol 22, No 2 (2017)
Special Issue Papers
Published online: 2017-03-01
Submitted: 2015-11-05
Get Citation

Evaluation of reproducibility of tumor repositioning during multiple breathing cycles for liver stereotactic body radiotherapy treatment

Ludovic Bedos, Olivier Riou, Norbert Aillères, Antoine Braccini, Jessica Molinier, Carmen Llacer Moscardo, David Azria, Pascal Fenoglietto
DOI: 10.1016/j.rpor.2016.07.007
·
Rep Pract Oncol Radiother 2017;22(2):132-140.

open access

Vol 22, No 2 (2017)
Special Issue Papers
Published online: 2017-03-01
Submitted: 2015-11-05

Abstract

Aim

To evaluate the tumor repositioning during gated volumetric modulated arc therapy (VMAT) for liver stereotactic body radiotherapy(SBRT) treatment using implanted fiducial markers and intrafraction kilovoltage (kV) images acquired during dose delivery.

Materials and methods

Since 2012, 47 liver cancer patients with implanted fiducial markers were treated using the gated VMAT technique with a Varian Truebeam STx linear accelerator. The fiducial markers were implanted inside or close to the tumor target before treatment simulation. They were defined at the maximum inhalation and exhalation phases on a 4-dimensionnal computed tomography (4DCT) acquisition. During the treatment, kV images were acquired just before the beam-on at each breathing cycle at maximum exhalation and inhalation phases to verify the fiducial markers positions. For the five first fractions of treatment in the first ten consecutive patients, a total of 2705 intrafraction kV images were retrospectively analyzed to assess the differences between expected and actual positions of the fiducial markers along the cranio-caudal (CC) direction during the exhalation phase.

Results

The mean absolute intrafractional fiducial marker deviation along the CC direction was 1.0[[ce:hsp sp="0.25"/]]mm at the maximum exhalation phase. In 99%, 95% and 90% cases, the fiducial marker deviations were ≤4.5[[ce:hsp sp="0.25"/]]mm, 2.8[[ce:hsp sp="0.25"/]]mm and 2.2[[ce:hsp sp="0.25"/]]mm, respectively.

Conclusion

Intrafraction kV images allowed us to ensure the consistency of tumor repositioning during treatment. In 99% cases, the fiducial marker deviations were ≤4.5[[ce:hsp sp="0.25"/]]mm corresponding to our 5[[ce:hsp sp="0.25"/]]mm treatment margin. This margin seems to be well-adapted to the gated VMAT SBRT treatment in liver disease.

Abstract

Aim

To evaluate the tumor repositioning during gated volumetric modulated arc therapy (VMAT) for liver stereotactic body radiotherapy(SBRT) treatment using implanted fiducial markers and intrafraction kilovoltage (kV) images acquired during dose delivery.

Materials and methods

Since 2012, 47 liver cancer patients with implanted fiducial markers were treated using the gated VMAT technique with a Varian Truebeam STx linear accelerator. The fiducial markers were implanted inside or close to the tumor target before treatment simulation. They were defined at the maximum inhalation and exhalation phases on a 4-dimensionnal computed tomography (4DCT) acquisition. During the treatment, kV images were acquired just before the beam-on at each breathing cycle at maximum exhalation and inhalation phases to verify the fiducial markers positions. For the five first fractions of treatment in the first ten consecutive patients, a total of 2705 intrafraction kV images were retrospectively analyzed to assess the differences between expected and actual positions of the fiducial markers along the cranio-caudal (CC) direction during the exhalation phase.

Results

The mean absolute intrafractional fiducial marker deviation along the CC direction was 1.0[[ce:hsp sp="0.25"/]]mm at the maximum exhalation phase. In 99%, 95% and 90% cases, the fiducial marker deviations were ≤4.5[[ce:hsp sp="0.25"/]]mm, 2.8[[ce:hsp sp="0.25"/]]mm and 2.2[[ce:hsp sp="0.25"/]]mm, respectively.

Conclusion

Intrafraction kV images allowed us to ensure the consistency of tumor repositioning during treatment. In 99% cases, the fiducial marker deviations were ≤4.5[[ce:hsp sp="0.25"/]]mm corresponding to our 5[[ce:hsp sp="0.25"/]]mm treatment margin. This margin seems to be well-adapted to the gated VMAT SBRT treatment in liver disease.

Get Citation

Keywords

Gated VMAT; Intrafraction target motion verification; Respiratory gating

About this article
Title

Evaluation of reproducibility of tumor repositioning during multiple breathing cycles for liver stereotactic body radiotherapy treatment

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 22, No 2 (2017)

Pages

132-140

Published online

2017-03-01

DOI

10.1016/j.rpor.2016.07.007

Bibliographic record

Rep Pract Oncol Radiother 2017;22(2):132-140.

Keywords

Gated VMAT
Intrafraction target motion verification
Respiratory gating

Authors

Ludovic Bedos
Olivier Riou
Norbert Aillères
Antoine Braccini
Jessica Molinier
Carmen Llacer Moscardo
David Azria
Pascal Fenoglietto

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: journals@viamedica.pl