Open AccessFiducial marker position affects target volume in stereotactic lung irradiation
Author(s) -
Akasaka Hiroaki,
Mizonobe Kazufusa,
Oki Yuya,
Uehara Kazuyuki,
Nakayama Masao,
Tamura Shuhei,
Munetomo Yoshiki,
Kawaguchi Haruna,
Ishida Jun,
Harada Aya,
Ishihara Takeaki,
Kubota Hikaru,
Kawaguchi Hiroki,
Sasaki Ryohei,
Mayahara Hiroshi
Publication year - 2022
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.13596
Subject(s) - fiducial marker , cyberknife , medicine , nuclear medicine , radiosurgery , lung , radiation therapy , lung cancer , radiology , pathology
Purpose Real‐time tracking systems of moving respiratory targets such as CyberKnife, Radixact, or Vero4DRT are an advanced robotic radiotherapy device used to deliver stereotactic body radiotherapy (SBRT). The internal target volume (ITV) of lung tumors is assessed through a fiducial marker fusion using four‐dimensional computed tomography (CT). It is important to minimize the ITV to protect normal lung tissue from exposure to radiation and the associated side effects post SBRT. However, the ITV may alter if there is a change in the position of the fiducial marker with respect to the tumor. This study investigated the relationship between fiducial marker position and the ITV in order to prevent radiation exposure of normal lung tissue, and correct target coverage. Materials and methods This study retrospectively reviewed 230 lung cancer patients who received a fiducial marker for SBRT between April 2015 and September 2021. The distance of the fiducial marker to the gross tumor volume (GTV) in the expiratory ( d ex ) and inspiratory ( d in ) CT, and the ratio of the ITV/V(GTV ex ), were investigated. Results Upon comparing each lobe, although there was no significant difference in the d diff and the ITV/V(GTV ex ) between all lobes for d ex < 10 mm, there was significant difference in the d diff and the ITV/V(GTV ex ) between the lower and upper lobes for d ex ≥ 10 mm ( p < 0.05). Moreover, there was significant difference in the d diff and the ITV/V(GTV ex ) between d ex ≥10 mm and d ex < 10 mm in all lung regions ( p < 0.05). Conclusion The ITV that had no margin from GTVs increased when d ex was ≥10 mm for all lung regions ( p < 0.05). Furthermore, the increase in ITV tended to be greater in the lower lung lobe. These findings can help decrease the possibility of adverse events post SBRT, and correct target coverage.