Accuracy of image guidance using free-breathing cone-beam computed tomography for stereotactic lung radiotherapy

Takeshi Kamomae; Hajime Monzen; Shinichi Nakayama; Rika Mizote; Yuuichi Oonishi; Soichiro Kaneshige; Takashi Sakamoto

doi:10.1371/journal.pone.0126152

Accuracy of image guidance using free-breathing cone-beam computed tomography for stereotactic lung radiotherapy

PLoS One. 2015 May 8;10(5):e0126152. doi: 10.1371/journal.pone.0126152. eCollection 2015.

Authors

Takeshi Kamomae¹, Hajime Monzen², Shinichi Nakayama³, Rika Mizote³, Yuuichi Oonishi³, Soichiro Kaneshige⁴, Takashi Sakamoto⁴

Affiliations

¹ Department of Therapeutic Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Radiation Oncology, Okayama Central Hospital, Okayama, Japan.
² Department of Radiation Oncology, Graduate School of Medical Science, Kinki University, Osaka, Japan.
³ Division of Clinical Radiology Service, Okayama Central Hospital, Okayama, Japan.
⁴ Department of Radiation Oncology, Okayama Central Hospital, Okayama, Japan.

Abstract

Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 ± 0.09, 0.16 ± 0.07, and 0.05 ± 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 ± 0.22, 0.07 ± 0.25, and -0.79 ± 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 ± 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cone-Beam Computed Tomography*
Four-Dimensional Computed Tomography
Humans
Lung Neoplasms / radiotherapy*
Phantoms, Imaging
Radiotherapy, Image-Guided
Respiration

Grants and funding

This work was supported by the Foundation for Promotion of Cancer Research in Japan (http://www.fpcr.or.jp). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional funding was received for this study.