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Using FFF beams to improve the therapeutic ratio of lung SBRT

Published online by Cambridge University Press:  30 July 2020

Oleg N. Vassiliev Open the ORCID record for Oleg N. Vassiliev [Opens in a new window] ,
Christine B. Peterson ,
Joe Y. Chang  and
Radhe Mohan
Oleg N. Vassiliev*
Affiliation:
Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
Christine B. Peterson
Affiliation:
Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
Joe Y. Chang
Affiliation:
Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
Radhe Mohan
Affiliation:
Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
*
Author for correspondence: Oleg N. Vassiliev, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX77030, USA. Tel: +1 713-745-7995. Fax: +1 713-563-6949. E-mail: onvassil@mdanderson.org
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Abstract

Aim:

The aim of this study was to investigate the extent to which lung stereotactic body radiotherapy (SBRT) treatment plans can be improved by replacing conventional flattening filter (FF) beams with flattening filter-free (FFF) beams.

Materials and methods:

We selected 15 patients who had received SBRT with conventional 6-MV photon beams for early-stage lung cancer. We imported the patients’ treatment plans into the Eclipse 13·6 treatment planning system, in which we configured the AAA dose calculation model using representative beam data for a TrueBeam accelerator operated in 6-MV FFF mode. We then created new treatment plans by replacing the conventional FF beams in the original plans with FFF beams.

Results:

The FFF plans had better target coverage than the original FF plans did. For the planning target volume, FFF plans significantly improved the D98, D95, D90, homogeneity index and uncomplicated tumour control probability. In most cases, the doses to organs at risk were lower in FFF plans. FFF plans significantly reduced the mean lung dose, V10, V20, V30, and normal tissue complication probability for the total lung and improved the dosimetric indices for the ipsilateral lung. For most patients, FFF beams achieved lower maximum doses to the oesophagus, heart and the spinal cord, and a lower chest wall V30.

Conclusions:

Compared with FF beams, FFF beams achieved lower doses to organs at risk, especially the lung, without compromising tumour coverage; in fact, FFF beams improved coverage in most cases. Thus, replacing FF beams with FFF beams can achieve a better therapeutic ratio.

Keywords

lung SBRTFFF beamstumor controlcomplication probability
Type
Original Article
Information
Journal of Radiotherapy in Practice , Volume 20 , Issue 4 , December 2021 , pp. 419 - 425
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Copyright
© The Author(s), 2020. Published by Cambridge University Press

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