1. Active Breathing Control in Combination With Ultrasound Imaging: A Feasibility Study of Image Guidance in Stereotactic Body Radiation Therapy of Liver Lesions 
Esther Bloemen-van Gurp, PhD, Skadi van der Meer, MSc, Janet Hendry, MSc, Jeroen Buijsen, MD, Peter Visser, MSc, Davide Fontanarosa, MSc, Martin Lachaine, PhD, Guido Lammering, MD, PhD, Frank Verhaegen, PhD 
International Journal of Radiation Oncology • Biology • Physics 
Volume 85, Issue 4, Pages (March 2013)
DOI: /j.ijrobp
Copyright © 2013 Elsevier Inc. Terms and Conditions

2. Fig. 1
(a) Prototype of US probe designed for optimal scanning of liver and surrounding structures. (b) SDX spirometer system. (c) display of the breathing signal and sequential BH in 50% expiration, used for US scanning.
International Journal of Radiation Oncology • Biology • Physics  , DOI: ( /j.ijrobp )
Copyright © 2013 Elsevier Inc. Terms and Conditions

3. Fig. 2
Intraobserver variability (a) and interobserver variability (b) determined for free breathing and breath-hold ultrasound scanning. (c) Repeated scan and match reproducibility.
International Journal of Radiation Oncology • Biology • Physics  , DOI: ( /j.ijrobp )
Copyright © 2013 Elsevier Inc. Terms and Conditions

4. Fig. 3
Ultrasound image of part of the liver (contoured in black) and the right kidney (contoured in white) acquired in breath-hold and free breathing, respectively. Deformation due to motion artifacts is clearly visible in the free breathing images compared with the breath-hold images. They increase the uncertainty of image segmentation.
International Journal of Radiation Oncology • Biology • Physics  , DOI: ( /j.ijrobp )
Copyright © 2013 Elsevier Inc. Terms and Conditions