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Feasibility of real-time lung tumor motion monitoring using intrafractional ultrasound and kV cone beam projection images. Med Phys 2018 Oct;45(10):4619-4626

Date

07/27/2018

Pubmed ID

30047160

DOI

10.1002/mp.13104

Scopus ID

2-s2.0-85052460630   5 Citations

Abstract

PURPOSE: The ability to monitor intrafractional tumor motion is essential for radiation therapy of thoracic and abdominal tumors. This study aims to develop a method to track lung tumor motion using intrafractional continuous ultrasound (US) and periodic cone-beam projection images (CBPI).

METHODS: Time-sequenced b-mode US and CBPI data were extracted from the data acquired with the Clarity® and XVI platforms on an Elekta linac, respectively. The data were synchronized through a video capture card (VCE-PRO, IMPERX Inc.) which was triggered by the XVI system. In this way, a system was configured to allow real-time acquisition of the diaphragm position synchronized with periodic acquisition of the lung tumor position. Feasibility of the system was demonstrated by acquiring synchronized data on an in-house motion platform with embedded spheres of different materials and US images of the diaphragm on 5 volunteers of various body sizes. Finally, ultrasound b-mode images and CBPI were also acquired simultaneously from 3 lung cancer patients.

RESULTS: Diaphragm motion monitoring under free breathing (FB) was successful with intracostal US imaging. We observed that diaphragm visualization decreased with the increase in the body size of the volunteer. The US system was able to track the motion as small as 2 mm in the phantom. The intrafractional CBPI acquired during VMAT delivery was successfully synchronized with US acquisition in a phantom study. Collected patient data showed a significant correlation between diaphragm motion, an internal surrogate monitored by US, and the tumor motion in superior-inferior (SI) direction monitored by XVI (P ˂ 0.0001).

CONCLUSIONS: The feasibility of real-time lung tumor motion tracking in SI direction with continuous ultrasound and periodic CBPI was demonstrated. The real-time estimation of the target position from the two streams for lung cancer patients would enable respiration gating or tracking during SBRT.

Author List

Mostafaei F, Tai A, Gore E, Johnstone C, Haase W, Ehlers C, Cooper DT, Lachaine M, Li XA

Authors

Elizabeth M. Gore MD Professor in the Radiation Oncology department at Medical College of Wisconsin
Candice A. Johnstone MD, MPH Associate Professor in the Radiation Oncology department at Medical College of Wisconsin
X Allen Li PhD Professor in the Radiation Oncology department at Medical College of Wisconsin
An Tai PhD Associate Professor in the Radiation Oncology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Cone-Beam Computed Tomography
Feasibility Studies
Humans
Lung Neoplasms
Movement
Phantoms, Imaging
Radiotherapy, Image-Guided
Respiration
Time Factors
Ultrasonography
jenkins-FCD Prod-480 9a4deaf152b0b06dd18151814fff2e18f6c05280