Technical evaluation of a laser-based optical surface scanning system for prospective and retrospective breathing adapted computed tomography

Figures & data

Figure 1. The Sentinel^TM unit mounted in the ceiling above the foot end of the CT couch. The solid lines illustrate the laser beam sweeping over the patient and the dashed lines illustrate the scattered light registered by the camera.

Figure 2. The platform made of transparent plastic mounted on the Hexamotion phantom.

Figure 3. Fourier spectra of recorded and generated data. Shaded regions defines the peaks.

Figure 4. CT-image of the phantom. Amplitude (A) was defined as the distance between the upper surface of the aluminum rod (1) placed on the moving platform (2) and the couch. The dense structure in the middle of the platform is a spirit-level (3) used for adjusting the platform. Plastic slabs (4) were placed on the couch to prevent couch from bending.

Table I. The ratio between area of the peak in the recorded and the generated breathing data at the fundamental frequency, first harmonic frequency and second harmonic frequency.

Trajectory	AZ-733V	RPM^™	Sentinel^™
2 s/1.67 mm	1.02, 0.64, 0.48	1.03, 0.68, 0.14	1.01, 0.58, 0.54
5s /1.67 mm	1.10, 0.63, 0.59	1.03, 0.58, 0,16	0.98, 0.34, 0.81
2 s/3.33 mm		1.02, 0.66, 0.46	1.05, 0.61, 0.53
5 s/3.33 mm		1.05, 0.64, 1.19	1.08, 0.70, 0.50
2 s/5 mm	1.01, 0.54, 0.54	1.04, 0.72, 0.30	1.11, 0.70, 0.65
5 s/5 mm	0.52, 0.41, 0.43	1.04, 0.71, 0.52	1.04, 0.76, 0.33
2 s/6.67 mm		0.99, 0.73, 0.38	1.01, 0.79, 0.68
5 s/6.67 mm		1.03, 0.74, 0.54	1.03, 0.79, 0.30
2 s/10 mm		0.92, 0.79, 0.53	0.98, 0.83, 1.28
5 s/10 mm		1.04, 0.70, 0.86	1.07, 0.83, 1.51

Table II. Mean phase shift (± 1 s.d.) calculated for the three systems and trajectories.

	Trajectory
System	3 mm	5 mm	10 mm
AZ-733V	1.46 ± 0	1.47 ± 0	1.52 ± 0
RPM^™	1.15 ± 0.17	1.20 ± 0.20	1.30 ± 0.01
Sentinel^™	1.31 ± 0.17	1.43 ± 0.16	1.50 ± 0.05