The Study On Accuracy Of Pedicle Screw Placement In Cervical Spine Surgery Under CT Navigation And Study Of Radiation Dose Rate Distribution For Mobile X-ray Unit In Operating Room And Suggestions For Protection

Purpose:1. Discuss the application experience and the effect of cervical pediclescrews internal fixation with using intraoperative CT navigation andsimpleintraoperative CT scans auxiliary.2. Organs dose equivalent calculates when CT scanunder the conditions of operation.3.Study of the operating room c-shaped arm level ofradiation dose rate distribution and to protect the protective measures adopted by thestaff.Methods:1.Conclusion using intraoperative CT diagnosis of cervical spondylosis,cervical spine trauma, tumor,93cases of patients with cervical spine. Postoperativelevels of CT scan in the pedicle screws. Nonrandomized method2groups (according tothe patient’s choice), intraoperative CT navigation and intraoperative CT navigationgroup, intraoperative CT navigation group,25patients under intraoperative CTnavigation surgery, simple intraoperative CT surgery group of68patients inintraoperative CT aided by according to the standard operation procedure to complete.Postoperative levels of CT scan in the pedicle screws, to observe the accuracy ofpedicle screw placement. Record the detailed operation steps two groups of patients,preoperative, perioperative of image data. Two groups of pedicle screws were analyzedthe accuracy of nailing renovation rate, and the time and intraoperative CT scan data.2.Thermal release the filter sheet is placed in the light phantom, according to theoperation conditions for the irradiation, we read out the count value with the instrument,by the scale factor in terms of absorbed dose, and then radiation weighting factors,organ weighting factors to calculate the effective dose3. The C-arm is placed in the room with shielding surgery with radiation field as concentric circles around the distribution radius interval of1m, measurement, recordingtraceable to national measurement standards Fluke451B-shaped radiation monitor.Thus, the dose rate results in different operating room location.Results:1. Intraoperative CT navigation set screw placement satisfaction rate was98.3%, Non navigation set screw placement satisfaction rate was93.1%, two groups ofsatisfaction have significant difference (P <0.05). Position is not satisfied with fourscrews in navigation group were occurred in early cases, navigation group didn’treappear dissatisfied cases after skilled. Two groups of cases no significant nerve,blood vessel damage complications. The average time intraoperative tool isregistered and the reference points is3.5min (2-8min), position error rate, on average,0.31mm (0.120.56mm, navigator automatic computing). Time needed for eachpedicle screw positioning needle into an average of2.02min (1-3.5min). Thenavigation group time needed for each pedicle screw positioning needle into anaverage of3.07min (2.07to4.09min). Do not need to overhaul cases, intraoperativejust2times CT to register and verify the accuracy of screw placement, overhaul needs3CT cases. Between the two groups has a more significant differences in the followingrespects:(1) cervical screw spikes worn out rate;(2) average time nailing;(3) theaverage intraoperative CT scan time and operation the pause time;(4) the averageintraoperative CT scan. Navigate from the navigation group of cervical screw spikesworn out rate, screw renovation rate and average time nailing is decreased obviously.Two groups were significant differences in satisfaction (P <0.05). Two groups ofcases haven’t significant nerve, blood vessel damage complications. There weren’tcases of secondary surgery due to poor plant location in the2groups.2. The spineeven spiral illuminate, therefore each organ dose equivalent difference; Lesssuperficial organ located on the skin surface, shielding, by the larger irradiation dose,such as thyroid, its dose is14.17mGy; Consists of cervical vertebra, thoracic vertebra,lumbar spine, its minimum dose of lumbar spine,7.53mGy, cervical vertebra is thelargest,9.68mGy, related to the corresponding position of the vertebral body, thoracicvertebra, dose is7.64mGy. The top of the neck,15.75mGy, and thyroid maximum anastomosis in above table, shows that in the process of scanning, the largest organ ofthe patient’s body by dose of thyroid, therefore, under the premise of without affectingthe operation should be for its protection.3. The radiation dose rate for mobile C-ArmDevices attenuates by inverse distance of factor2.278influenced by spatial layout,with the outside of protective screen area, the adjacent operating rooms and thecorridors attenuates to background levels. The distribution of radiation dose rate in theoperating room is affected by the horizontal, vertical direction of ray generator, thusaffect the dose of the radiation workers received working in the operating room atdifferent position.Conclusion:1. Intraoperative CT aided navigation system for cervical pedicle screwfixation is feasible, can significantly improve the posterior cervical spine pediclescrews the accuracy, the security of the nailing [2], medical personnel without X rayexposure at the same time.2. In the process of operation，according to the provisionsof intraoperative CT, c-shaped arm operation and personal protection, we caneffectively reduce the staff of radiation risk, better protect personal occupationalhealth.