Usefulness of target delineation based on the two extreme phases of a four‐dimensional computed tomography scan in stereotactic body radiation therapy for lung cancer

Thoracic Cancer

Seong Soon Jang³  Gil Ja Huh³  Suk Young Park¹  Po Song Yang² 

[1] Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea;Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea;Department of Radiation Oncology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea

关键词: 4D CT;    lung cancer;    planning target volume;    stereotactic body radiation therapy;   

DOI  :  10.1111/1759-7714.12170

来源: Wiley

【 摘 要 】

Abstract

Background

An evaluation of the usefulness of target delineation based only on the two extreme phases of a four-dimensional computed tomography (4D CT) scan in lung stereotactic body radiation therapy (SBRT).

Methods

Seventeen patients treated with SBRT via 4D CT scans for lung cancer were retrospectively enrolled. Volumetric and geometric analyses were performed for the internal target volumes (ITVs) and planning target volumes (PTVs) generated using different respiratory phases (all phases and 2 extreme phases) and setup margins (3 mm and 5 mm).

Results

As the setup margins were added to the ITVs, the overlap percentage between the PTVs based on all phases and the two extreme phases increased (85.1% for ITVs, 89.8% for PTVs_3 mm, and 91.3% for PTVs_5 mm), and there were no differences according to the tumor parameters, such as the gross tumor volume and 3D mobility. The missing-volume differences for ITVs derived from cone-beam CT images also decreased, with values of 5.3% between ITVs, 0.5% between PTVs_3 mm, and 0.2% between PTVs_5 mm. Compared with the plan based on all phases and a 3 mm margin, the average lung-dose differences found for the PTV based on the two extreme phases and a 5 mm margin were 0.41 Gy for the mean lung dose and 0.93% for V20.

Conclusions

Regardless of tumor characteristics, PTV construction based only on the two extreme phases and a 5 mm setup margin may be a useful tool for reducing the clinical workload involved in target delineation in SBRT for lung cancer.

【 授权许可】

CC BY-NC   
© 2014 The Authors. Thoracic Cancer published by Tianjin Lung Cancer Institute and Wiley Publishing Asia Pty Ltd.

Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.