Open AccessThe effect of image‐guided radiation therapy on the margin between the clinical target volume and planning target volume in lung cancer
Author(s) -
Liang Jun,
Li Minghui,
Zhang Tao,
Han Wei,
Chen Dongfu,
Hui Zhouguang,
Lv Jima,
Zhang Zhong,
Zhang Yin,
Zhang Liansheng,
Zheng Rong,
Dai Jianrong,
Wang Luhua
Publication year - 2014
Publication title -
journal of medical radiation sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 18
eISSN - 2051-3909
pISSN - 2051-3895
DOI - 10.1002/jmrs.42
Subject(s) - image guided radiation therapy , margin (machine learning) , medicine , radiation therapy , nuclear medicine , lung cancer , imaging phantom , radiation treatment planning , radiology , computer science , oncology , machine learning
This study aimed to evaluate the effect of image‐guided radiation therapy ( IGRT ) on the margin between the clinical target volume ( CTV ) and planning target volume ( PTV ) in lung cancer. Methods The CTV and PTV margin were determined in three dimensions by four radiation oncologists using a standard method in 10 lung cancer patients, and compared to consensus values. Transfer error was measured using a rigid phantom containing gold markers. Systematic error ( ∑ setup ) and random error ( σ setup ) set up errors were calculated in three dimensions from pre‐treatment and post‐treatment cone beam CT scans. Finally, the margin between the CTV and PTV was corrected for set up error and calculated. Results The margins between the CTV and PTV with IGRT (and without IGRT ) were 0.88 cm (0.96 cm), 0.99 cm (1.08 cm) and 1.28 cm (1.82 cm) in the anterior and posterior ( AP ), left and right ( LR ) and superior and inferior ( SI ) directions, respectively. Images from two other patients verified the validity of the corrected margin. The target delineation errors of the radiation oncologists are considered to be the largest compared with the set up errors. The application of IGRT reduced the set up errors and the margins between CTV and PTV . Conclusions The delineation errors of radiation oncologists are the most important factor to consider for the margin between CTV and PTV for lung cancer. IGRT can reduce the margins by reducing the set up errors, especially in the SI direction. Further research is required to assess whether the reduction in the margin is solely based on set up errors.