Robot-assisted thoracoscopic brachytherapy for lung cancer: Comparison of the ZEUS robot, VATS, and manual seed implantation

Figures & data

Figure 1. The set-up for the experiments with the ZEUS system using the injector to insert seeds into agar cubes within the VATS box. The surgeon could only see the agar cube on the monitor. [Color version available online.]

Figure 2. Schematic diagram of the customized seed injector for the ZEUS robotic system.

Figure 3. Radiograph of the agar cubes showing the deposited seeds and the steel balls that act as targets. These images were used to measure the distance from the center of the seed to the center of the target with the ImageJ software.

Figure 4. The median accuracy of each method is displayed as the distance from the center of the injected seed to the center of the target. The accuracy of the ZEUS technique was inferior to that of the VATS technique by 1.2 mm.

Table I.  The accuracy of each method is displayed as the measured distance from the center of the injected seed to the center of the target.

Method	No. of seeds inserted	Mean (mm)	Std. dev. (mm)	Median (mm)	Min. (mm)	Max. (mm)	p
Manual	128	2.19	1.09	1.81	0.93	6.74
VATS	128	3.10	2.11	2.38	1.04	11.30	p < 0.001
ZEUS	128	4.60	3.16	3.60	1.30	16.69

Figure 5. The median number of attempts required for the needle to reach the target for each method. The ZEUS technique was superior to the VATS technique, requiring one less attempt on average.

Table II.  Number of attempts to reach the target for each method.

Method	No. of seeds inserted	Mean	Std. dev.	Median	Min.	Max.	p
Manual	128	1.03	0.35	1	1	5
VATS	128	4.92	2.92	4	1	14	p < 0.001
ZEUS	128	3.84	2.91	3	1	20

Figure 6. The median time required to insert the needle to the desired location for each method. The ZEUS technique was faster than the VATS technique by 22 s.

Table III.  Time required to insert the needle and deploy the seed to the desired location for each method.

Method	No. of seeds inserted	Mean (s)	Std. dev. (s)	Median (s)	Min. (s)	Max (s)	p
Manual	128	5	6	3	1	43
VATS	128	104	70	87	6	372	p < 0.001
ZEUS	128	85	69	65	5	356

Table IV.  Effect of training with the ZEUS robot. The latter halves of the experimental series show a reduction in the number of attempts and mean time required. There was no significant improvement in accuracy.

Amount of training	Mean accuracy (mm)	Mean attempts	Mean time (s)
First half	4.41	4.31	101.61
Latter half	4.78	3.36	68.91
p value	0.543	0.026	0.007

Table V.  Comparison of surgeons versus non-surgeons using the ZEUS robot. There was no significant difference in the number of attempts and time required with respect to the level of training. However, surgeons were significantly more accurate than non-surgeons.

Level of training	Mean accuracy (mm)	Mean attempts	Mean time (s)
Surgeons	4.03	3.98	93.67
Non-surgeons	5.23	3.90	98.44
p value	0.048	0.89	0.75