Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Jan-Feb;24(1):97-104.
doi: 10.1016/j.rpor.2018.11.003. Epub 2018 Nov 24.

Tracking, gating, free-breathing, which technique to use for lung stereotactic treatments? A dosimetric comparison

Jessica Prunaretty  1 , Pierre Boisselier  1 , Norbert Aillères  1 , Olivier Riou  1 , Sebastien Simeon  1 , Ludovic Bedos  1 , David Azria  1 , Pascal Fenoglietto  1
Affiliations

Tracking, gating, free-breathing, which technique to use for lung stereotactic treatments? A dosimetric comparison

Jessica Prunaretty et al. Rep Pract Oncol Radiother. 2019 Jan-Feb.

Abstract

Background: The management of breath-induced tumor motion is a major challenge for lung stereotactic body radiation therapy (SBRT). Three techniques are currently available for these treatments: tracking (T), gating (G) and free-breathing (FB).

Aim: To evaluate the dosimetric differences between these three treatment techniques for lung SBRT.

Materials and methods: Pretreatment 4DCT data were acquired for 10 patients and sorted into 10 phases of a breathing cycle, such as 0% and 50% phases defined respectively as the inhalation and exhalation maximum. GTVph, PTVph (=GTVph + 3 mm) and the ipsilateral lung were contoured on each phase.For the tracking technique, 9 fixed fields were adjusted to each PTVph for the 10 phases. The gating technique was studied with 3 exhalation phases (40%, 50% and 60%). For the free-breathing technique, ITVFB was created from a sum of all GTVph and a 3 mm margin was added to define a PTVFB. Fields were adjusted to PTVFB and dose distributions were calculated on the average intensity projection (AIP) CT. Then, the beam arrangement with the same monitor units was planned on each CT phase.The 3 modalities were evaluated using DVHs of each GTVph, the homogeneity index and the volume of the ipsilateral lung receiving 20 Gy (V 20Gy).

Results: The FB system improved the target coverage by increasing D mean (75.87(T)-76.08(G)-77.49(FB)Gy). Target coverage was slightly more homogeneous, too (HI: 0.17(T and G)-0.15(FB)). But the lung was better protected with the tracking system (V 20Gy: 3.82(T)-4.96(G)-6.34(FB)%).

Conclusions: Every technique provides plans with a good target coverage and lung protection. While irradiation with free-breathing increases doses to GTV, irradiation with the tracking technique spares better the lung but can dramatically increase the treatment complexity.

Keywords: Dosimetric comparison; Free-breathing; Gating; Lung SBRT; Tracking.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Description of the analysis process for the comparison of the free-breathing, tracking and gating techniques.
Fig. 2
Fig. 2
Dose volume histograms comparing the gross tumor volume (GTV), the planning tumor volume (PTV) and the normal lung volume for the free-breathing (FB), tracking (T) and gating (G) techniques.
See this image and copyright information in PMC

References

    1. Timmerman R., Papiez L., McGarry R. Extracranial stereotactic radioablation: results of a phase I study in medically inoperable stage I non-small cell lung cancer patients. Chest. 2003;124(5):1946–1955. - PubMed
    1. Nagata Y., Negoro Y., Aoki T. Clinical outcomes of 3D conformal hypofractionated single high-dose radiotherapy for one or two lung tumors using a stereotactic body frame. Int J Radiat Oncol Biol Phys. 2002;52:1041–1046. - PubMed
    1. Hof H., Herfath K., Münter M. Stereotactic single-dose radiotherapy of stage i non-small-cell lung cancer (Nsclc) Int J Radiat Oncol Biol Phys. 2003;56:335–341. - PubMed
    1. Wulf J., Haedinger U., Oppitz U., Thiele W., Mueller G., Flentje M. Stereotactic radiotherapy for primary lung cancer and pulmonary metastases: a noninvasive treatment approach in medcally inoperable patients. Int J Radiat Oncol Biol Phys. 2004;60(1):186–196. - PubMed
    1. Seppenwoolde Y., Shirato H., Kitamura K. Precise and real-time measurement of 3D tumor motion due to breathing and heartbeat, measured during radiotherapy. Int J Radiat Oncol Biol Phys. 2002;53:822–834. - PubMed