Available range analysis of laser guidance system and its application to monolithic integration with optical tracker

Fluoroscopic images-based aiming and targeting system with two line lasers for insertion guidance of interlocking screw

PURPOSE

Minimally invasive surgery is widely used for managing fractures; however, it is difficult to determine the exact screwing position of intramedullary nails inserted into bone. To address this problem, we developed the aiming and targeting system by laser (ATLAS) using two line lasers to mark the position of the surgical tool directly on the skin.

METHODS

ATLAS consists of a laser module, controller, personal computer, and display device. The laser module is fixed to the intensifier side of the C-arm. Calibration with dedicated markers is required prior to using the system. After calibration, the laser modules can mark the selected point on a fluoroscopic image acquired with the C-arm as the intersection of the two line lasers on the skin.

RESULTS

To verify the effectiveness of ATLAS, marking accuracy was measured. The average control error of the device itself was 0.57 mm. In the experimental setting using C-arm fluoroscopy, the accuracy was within 1.5 mm at 23 of the 25 measurement points and within 3 mm at the remaining two points.

CONCLUSION

ATLAS shows the corresponding points in real space with respect to fluoroscopic images using cross-points of lasers. The proposed method is clinically useful to aid the insertion of interlocking screws in minimally invasive surgeries for bone fractures. We believe that ATLAS enables more accurate marking through C-arm fluoroscopy and is more convenient, and it can thus be applied in various orthopedic surgeries.

Fluoroscopy-based laser guidance system for linear surgical tool insertion depth control

PURPOSE

In most orthopedic surgeries, knowing how far to insert surgical tools is crucial. The objective of this study was to provide guidance information on depth without tracking surgical tools. A previously developed laser guidance system for linear surgical tool insertion uses two laser beams that display the insertion point and orientation on the skin surface. However, the system only provides 4 degrees of freedom guidance (an entry point on the planned pathway line and the orientation) but do not inform surgeons on the ideal insertion depth.

METHOD

A 5-DOF guidance method was developed to provide guidance information by direct projection onto the surgical area using laser beams without tracking markers. A position and orientation guidance performed by two laser beams and depth guidance performed by a single laser beam are appeared on the surgical area in turn. However, depth point appears on the surgical tool side face with some error because of tool radius. Using the actual depth position, insertion path vector and location of the laser sources, the correct depth point on the tool's surface is calculated by the proposed method. So, this system can indicate and navigate the 5-DOF which is planning path and the correct depth point.

RESULTS

An evaluation of the accuracy of depth guidance revealed a depth guidance error of 0.55±0.29 mm and results from phantom target insertions revealed overall system accuracies of 1.44 ± 1.09 mm, 0.91° ± 0.82°. In addition, overall system accuracies of application feasibility experiment under the X-ray condition were 1.94 ± 0.98mm, 1.39° ± 1.30°.

CONCLUSION

A new surgical tool depth insertion method was developed using a fluorolaser guidance system. This tool informs surgeons of the surgical tool tip depth assuming that the insertion point and orientation are correct. The new method was tested successfully in vitro.

Surgical tool alignment guidance by drawing two cross-sectional laser-beam planes

Conventional surgical navigation requires for surgeons to move their sight and conscious off the surgical field when checking surgical tool's positions shown on the display panel. Since that takes high risks of surgical exposure possibilities to the patient's body, we propose a novel method for guiding surgical tool position and orientation directly in the surgical field by a laser beam. In our navigation procedure, two cross-sectional planar laser beams are emitted from the two laser devices attached onto both sides of an optical localizer, and show surgical tool's entry position on the patient's body surface and its orientation on the side face of the surgical tool. In the experiments, our method gave the surgeons precise and accurate surgical tool adjusting and showed the feasibility to apply to both of open and percutaneous surgeries.

A fluorolaser navigation system to guide linear surgical tool insertion

PURPOSE

Conventional navigation systems for minimally invasive orthopedic surgery require a secondary monitor to display guidance information generated with CT or MRI images. Newer systems use augmented reality to project surgical plans into binocular glasses. These surgical procedures are often mentally challenging and cumbersome to perform.

METHOD

A comprehensive surgical navigation system for direct guidance while minimizing radiation exposure was designed and built. System accuracy was evaluated using in vitro needle insertion experiments. The fluoroscopic-based navigation technique is combined with an existing laser guidance technique. As a result, the combined system is capable of surgical planning using two or more X-ray images rather than CT or MRI scans. Guidance information is directly projected onto the patient using two laser beams and not via a secondary monitor.

RESULTS

We performed 15 in vitro needle insertion experiments as well as 6 phantom pedicle screw insertion experiments to validate navigation system accuracy. The planning accuracy of the system was found to be 2.32 mm and 2.28°, while its overall guidance accuracy was found to be 2.40 mm and 2.39°. System feasibility was demonstrated by successfully performing percutaneous pin insertion on phantoms.

CONCLUSION

Quantitative and qualitative evaluations of the fluorolaser navigation system show that it can support accurate guidance and intuitive surgical tool insertion procedures without preoperative 3D image volumes and registration processes.

Development of the needle insertion robot for percutaneous vertebroplasty

Percutaneous Vertebroplasty (PVP) is an effective and less invasive medical treatment for vertebral osteoporotic compression fractures. However, this operative procedure is quite difficult because an arcus vertebra, which is narrow, is needled with accuracy, and an operator's hand is exposed to X-ray continuously. We have developed a needle insertion robot for Percutaneous Vertebroplasty. Its experimental evaluation on the basic performance of the system and needle insertion accuracy are presented. A needle insertion robot is developed for PVP. This robot can puncture with accuracy and an operator does not need to be exposed to X-ray. The mechanism of the robot is compact in size (350 mm x D 400 mm x H270 mm, weight: 15 kg) so that the robot system can be inserted in the space between C-arm and the patient on the operating table. The robot system is controlled by the surgical navigation system where the appropriate needle trajectory is planned based on pre-operative three-dimensional CT images. The needle holding part of the robot is X-ray lucent so that the needle insertion process can be monitored by fluoroscopy. The position of the needle during insertion process can be continuously monitored. In vitro evaluation of the system showed that average position and orientation errors were less than 1.0 mm and 1.0 degree respectively. Experimental results showed that the safety mechanism called mechanical fuse released the needle holding disk properly when excessive force was applied to the needle. These experimental results demonstrated that the developed system has the satisfactory basic performance as needle insertion robot for PVP.