The Key Technologies Research Of Trajectory Planning And Surgery Navigation In CT Image-guide Lung Puncture

Lung cancer has become one of the most fatal malignant cancers with the highest incidence.In its clinical diagnosis.the pathological examination of living tissue is the gold standard.The CT image-guided lung puncture is the most common method of lung biopsy,which still faces some difficulties in clinic.The location relationship between puncture needle and the lesion cannot be obtained in real time in surgery,in order to get the living tissue successfully,patients need to be repeated punctured and CT scanned to confirm the puncture needle position for 6-8 times averagely,which results in an increase of complications including pneumothorax and the risk of radioactive radiation.The CT image-guided lung puncture surgery navigation can solve these problems to guide surgeons to complete lung biopsy intelligently,improve the success rate and efficiency of surgery and reduce the damage to patients.This research focuses on the key problems in surgical trajectory planning and spatial registration,which are the two important aspects of CT image-guided lung puncture surgery navigation.In order to get optimal trajectory and improve the accuracy of space registration,the paper will study on the constrained multi-objective surgical trajectory optimization method based on clinical criterias,the automatic segmentation of the chest tissues and organs for surgical trajectory planning,the number and distribution optimization of fiducial markers based on point registration and the fiducial points localization method in the image space.Meanwhile,a CT image-guided lung puncture surgery navigation prototype system is also designed and implemented,which integrates the above four research results to further improve the accuracy and promote clinical application.The detailed research work of this dissertation is as follows:(1)A constrained multi-objective surgical trajectory optimization method based on clinical criterias for lung puncture surgery is proposed.This method analyzies and quantifies the clinical specific criterias,including the constraint criterias which must be observed in surgery and the objective criterias which can score different trajectories on the surgery risk.Six sub-objective functions based on the trajectory risk are defined,and the Pareto optimization method is used to find the optimal surgical trajectories based on them,which is not necessary to set the weight for each sub-objective or use a priori knowledge.It can reduce the influence of subjective factors on trajectory planning.Based on several sets of clinical successful lung puncture surgery data,the algorithm is evaluated by retrospective study and clinician blind assessment.The experimental results show that all optimal surgical trajectories calculated by our method are confirmed to be suitable for lung puncture surgery by the surgeons,which are considered to be better than most of the clinical surgical trajectories.(2)A segmentation strategy and method for chest tissues and organs is proposed for the surgical trajectory planning.In order to make surgeons and patients not waiting for long time,the execution time of all tissues and organs segmentation is needed to be as short as possible.Meanwhile,the segmentation results are also needed to meet the clinical accuracy requirements.A segmentation strategy based on the features of all chest tissues and organs is proposed to improve the segmentation efficiency,which is regional segmentation→structural identification→detail extraction.All organs including skin,lung parenchyma,trachea and bronchus,blood vessel,bone,mediastinum and lung fissure were segmented successfully and rapidly.The segmentation algorithm was evaluated based on several sets of clinical data.The average segmentation time was 127 seconds,which is confirmed to meet the clinic requirements on the speed and accuracy by the surgeons.The results of the organ segmentation can be used in the optimal trajectory planning,which also cannot make surgeons and patients wait for too long.(3)A number and distribution optimization method of fiducial markers for space registration in lung puncture surgery navigation system is proposed.The lung puncture surgery navigation system uses marker-based point registration to transform the patient spatial coordinate to the CT image coordinate.Based on the evaluation method of point registration error,the influence of the markers’ number and distribution on the registration error is analyzed.An accuracy assessment phantom is designed and a large number of registration experiments are carried out based on it.According to the experiment results,the optimal method on the number and spatial distribution of the markers is proposed.Using the optimization method to guide the surgeons to select and paste the markers for registration,the target point registration error is significantly reduced to enhance the registration accuracy for lung puncture surgery navigation.(4)An automatic fiducial marker detection and fiducial point localization method in image space for space recognition is proposed.The method is detect the fiducial marker and identify the fiducial point based on the shape features and the projection image of the marker on the CT image.with higher accuracy and robustness than conventional localization methods using prior parameters such as marker size.The method is not affected by the location and condition of the markers.The algorithm was evaluated based on several sets of clinical data,and the accuracy of our method is 14.3%higher than the traditional method using prior parameters.It can be used for space registration in lung puncture surgery navigation system to enhance the intelligence and precision of space registration and reduce the burden of doctors to identify the fiducial points manually.(5)Meanwhile,a CT-guided lung puncture surgery navigation prototype system is also designed and implemented in this paper,which integrates the above four research results to further improve the accuracy and reliability of the system and promote the practical application of the lung puncture surgery navigation system in clinical application.It realized the intelligent lung puncture surgery optimal trajectory planning method and accurate real-time surgery guidance method.The phantom and animal experiments on the performance of the system were evaluated.The experiment results show that the system has high precision,which can improve the success rate of surgery.reduce the harm of patients and the burden on surgeons.