Electromagnetic navigation improves minimally invasive robot-assisted lung brachytherapy

Figures & data

Figure 1. Experimental test-bed of MIRA IV at CSTAR.

Figure 2. Original InterNAV™ graphical user interface (a) and the modified InterNAV2.0™ (b). The main modifications include the following: The camera is oriented in line with the needle axis (for easier usage of the software); the control panel provides direct control of the robot motion and dropping of the seeds (for finer control over robot motions); a depth display (for increased penetration accuracy) has been introduced; and arrow guides are provided (for increased orientation accuracy). [Color version available online.]

Figure 3. Flow chart of component interaction in the MIRA IV with InterNAV2.0™ system. [Color version available online.]

Figure 4. The opaque agar cube (4.5 × 4.5 × 4.5 cm) used to simulate lung tissues beside the brachytherapy seed cylinder (0.8 × 5 mm) and the stainless steel bead (1.6 mm in diameter) used as a target.

Table I.  The five experimental setups.

Setup	Simulated operating environment	Guidance	Deposition
Manual	Open thoracotomy	Ultrasound	Manual
Standard VATS	MIS operation	Ultrasound	Manual
MIRA II	MIS operation	Ultrasound	Robot-assisted
MIRA III	MIS operation	Ultrasound + InterNAV™	Robot-assisted
MIRA IV	MIS operation	Ultrasound + InterNAV2.0™	Robot-assisted

Table II.  Summary of experimental results.

	Setup
Analysis	Manual	Standard VATS	MIRA II	MIRA III	MIRA IV	P value: MIRA IV vs. VATS	P value: MIRA IV vs. MIRA III
Time (s)	N = 78	N = 83	N = 78	N = 75	N = 80
Mean	36	151	120	85	44	<0.001	<0.001
Median	29	104	107	62	41
Range	7–150	26–665	39–301	28–267	22–112
No. of attempts
Mean	2.3	5.2	3.1	1.8	1.1	<0.001	<0.001
Median	2	4	3	1	1
Range	1–9	1–18	1–10	1–7	1–3
Accuracy (mm)
Mean	2.7	2.5	2.7	2.8	0.9	<0.001	<0.001
Std dev	1.3	1.5	1.6	1.5	0.7
Range	0.4–6.0	0–7.0	0.2–7.3	0.1–6.9	0–3.0

Figure 5. The accuracy of each method is displayed as the mean error. The MIRA IV system significantly improved the target accuracy by 64% (2.5 mm to 0.9 mm) compared to a standard VATS and by 68% (2.8 mm to 0.9 mm) compared to the MIRA III system without navigational guidance.

Figure 6. The MIRA IV system significantly reduced the median procedure time by 61% (104 s to 41 s) compared to a standard VATS and by 48% (85 s to 44 s) compared to the MIRA III system without navigational guidance.

Figure 7. The estimate of tissue trauma is based on the number of needle insertion attempts. The MIRA IV system significantly reduced tissue trauma by 75% (from 4 attempts to 1 attempt) when compared to a standard VATS.