@article {Xu2006a, title = {Lung deformation estimation and four-dimensional CT lung reconstruction}, journal = {Journal of Academic Radiology}, volume = {13}, number = {9}, year = {2006}, month = {Sep}, pages = {1082{\textendash}1092}, publisher = {Philips Research North America, 345 Scarborough Road, Briarcliff Manor, NY 10510, USA sheng xu@philips com}, abstract = {

RATIONALE AND OBJECTIVES: Four-dimensional (4D) computed tomography (CT) can be used in radiation treatment planning to account for respiratory motion Current 4D CT techniques have limitations in either spatial or temporal resolution In addition, most of these techniques rely on auxiliary surrogates to relate the time of the CT scan to the patient{\textquoteright}s respiratory phase We propose a 4D CT method for lung applications to overcome these problems MATERIALS AND METHODS: A set of axial scans are taken at multiple table positions to obtain a series of two-dimensional images while the patient is breathing freely Each two-dimensional image is registered to a reference CT volume The deformation of the image with respect to the volume is used to synchronize the image with the respiratory cycle assuming that there is no phase variation along the craniocaudal direction The reconstructed 4D dataset is a series of deformable transformations of the reference volume RESULTS: A synthetic 4D dataset showed that the registration error is less than 5\% of the image deformation A swine study showed that the algorithm can generate better image quality than the image sorting method A respiratory-gated 4D dataset showed that the algorithm{\textquoteright}s result is consistent with the ground truth CONCLUSION: The algorithm can reconstruct good quality 4D images without external surrogates even if the CT scans are acquired under irregular respiratory motion The algorithm may allow for reduced radiation dose to the patient with a limited loss of image quality Although the phase variation exists along the craniocaudal direction, the 4D reconstruction is reasonably accurate

}, keywords = {Algorithms, Artifacts, Computer-Assisted, Humans, Imaging, Information Storage, Lung, methods, Movement, Phantoms, Radiographic Image Enhancement, Radiographic Image Interpretation, Radiography, Reproducibility of Results, Respiratory Mechanics, Retrieval, Sensitivity, Specificity, Three-Dimensional, Tomography, X-Ray Computed}, doi = {10 1016/j acra 2006 05 004}, url = {http://dx doi org/10 1016/j acra 2006 05 004}, author = {Sheng Xu and Russell H. Taylor and Gabor Fichtinger and Kevin Cleary} } @article {Fichtinger2005, title = {Image overlay for CT-guided needle insertions}, journal = {Journal of Computer Aided Surgery}, volume = {10}, number = {4}, year = {2005}, month = {Jul}, pages = {241{\textendash}255}, abstract = {

OBJECTIVE: We present a 2D image overlay device to assist needle placement on computed tomography (CT) scanners MATERIALS AND METHODS: The system consists of a flat display, a semitransparent mirror mounted on the gantry When the physician looks at the patient through the mirror, the CT image appears to be floating inside the body with correct size, position as if the physician had 2D {\textquoteright}X-ray vision{\textquoteright} The physician draws the optimal path on the CT image The composite image is rendered on the display, thus reflected in the mirror The reflected image is used to guide the physician in the procedure In this article, we describe the design, various embodiments of the 2D image overlay system, followed by the results of phantom, cadaver experiments in multiple clinical applications RESULTS: Multiple skeletal targets were successfully accessed with one insertion attempt Generally, successful access was recorded on liver targets when a clear path opened, but the number of attempts, accuracy showed variability because of occasional lack of access Soft tissue deformation further reduced the accuracy, consistency in comparison to skeletal targets CONCLUSION: The system demonstrated strong potential for reducing faulty needle insertion attempts, thereby reducing X-ray dose, patient discomfort

}, keywords = {Animals, Biopsy, Cadaver, Calibration, Computer-Assisted, Equipment Design, Humans, Image Processing, Imaging, instrumentation, Interventional, Needle, Phantoms, Radiography, Swine, Tomography, User-Computer Interface, X-Ray Computed}, doi = {10 1080/10929080500230486}, url = {http://dx doi org/10 1080/10929080500230486}, author = {Gabor Fichtinger and Anton Degeut and Gregory Fischer and Iulian Iordachita and Emese Balogh and Ken Masamune and Russell H. Taylor and Laura Fayad and Michelle de Oliveira and James Zinreich} } @article {Xu2005b, title = {Lung deformation estimation and four-dimensional CT lung reconstruction}, journal = {Medical image computing and computer-assisted intervention (MICCAI)}, volume = {8}, number = {Pt 2}, year = {2005}, pages = {312{\textendash}319}, abstract = {

Four-dimensional (4D) computed tomography (CT) image acquisition is a useful technique in radiation treatment planning, interventional radiology in that it can account for respiratory motion of lungs Current 4D lung reconstruction techniques have limitations in either spatial or temporal resolution In addition, most of these techniques rely on auxiliary surrogates to relate the time of CT scan to the patient{\textquoteright}s respiratory phase In this paper, we propose a novel 4D CT lung reconstruction, deformation estimation algorithm Our algorithm is purely image based The algorithm can reconstruct high quality 4D images even if the original images are acquired under irregular respiratory motion The algorithm is validated using synthetic 4D lung data Experimental results from a swine study data are also presented

}, keywords = {Algorithms, Animals, Artificial Intelligence, Biological, Computer Simulation, Computer-Assisted, Elasticity, Humans, Imaging, Lung, methods, Models, physiology/radiography, Radiographic Image Enhancement, Radiographic Image Interpretation, Reproducibility of Results, Respiratory Mechanics, Sensitivity, Specificity, Swine, Three-Dimensional, Tomography, X-Ray Computed}, author = {Sheng Xu and Russell H. Taylor and Gabor Fichtinger and Kevin Cleary} } @article {Cleary2005, title = {Precision placement of instruments for minimally invasive procedures using a "needle driver" robot}, journal = {international journal of medical robotics computer assisted surgery MRCAS}, volume = {1}, number = {2}, year = {2005}, month = {Jan}, pages = {40{\textendash}47}, abstract = {

Medical practice continues to move toward less invasive procedures Many of these procedures require the precision placement of a needle in the anatomy Over the past several years, our research team has been investigating the use of a robotic needle driver to assist the physician in this task This paper summarizes our work in this area The robotic system is briefly described, followed by a description of a clinical trial in spinal nerve blockade The robot was used under joystick control to place a 22 gauge needle in the spines of 10 patients using fluoroscopic imaging The results were equivalent to the current manual procedure We next describe our follow-up clinical application in lung biopsy for lung cancer screening under CT fluoroscopy The system concept is discussed, the results of a phantom study are presented A start-up company named ImageGuide has recently been formed to commercialize the robot Their revised robot design is presented, along with plans to install a ceiling-mounted version of the robot in the CT fluoroscopy suite at Georgetown University

}, keywords = {Biopsy, Cadaver, Equipment Design, Fluoroscopy, Humans, Imaging, instrumentation, instrumentation/methods, Lung, Lung Neoplasms, methods, Minimally Invasive, Needles, Nerve Block, pathology, pathology/radiography, Phantoms, Randomized Controlled Trials as Topic, Robotics, Spinal Nerves, Surgical Procedures, Tomography, X-Ray Computed}, doi = {10 1002/rcs 40}, url = {http://dx doi org/10 1002/rcs 40}, author = {Kevin Cleary and Vance Watson and David Lindisch and Russell H. Taylor and Gabor Fichtinger and Sheng Xu and Charles White and John Donlon and Michael Taylor and Alexandru Patriciu and Dumitru Mazilu and Dan Stoianovici} } @article {Masamune2001, title = {System for robotically assisted percutaneous procedures with computed tomography guidance}, journal = {Journal of Computer Aided Surgery}, volume = {6}, number = {6}, year = {2001}, pages = {370{\textendash}383}, abstract = {

We present the prototype of an image-guided robotic system for accurate, consistent placement of percutaneous needles in soft-tissue targets under CT guidance inside the gantry of a CT scanner The couch-mounted system consists of a seven-degrees-of-freedom passive mounting arm, a remote center-of-motion robot, and a motorized needle-insertion device Single-image-based coregistration of the robot, image space is achieved by stereotactic localization using a miniature version of the BRW head frame built into the radiolucent needle driver The surgeon plans, controls the intervention in the scanner room on a desktop computer that receives DICOM images from the scanner The system does not need calibration, employs pure image-based registration, and does not utilize any vendor-specific hardware or software features In the open air, where there is no needle-tissue interaction, we systematically achieved an accuracy better than 1 mm in hitting targets at 5-8 cm from the fulcrum point In the phantom, the orientation accuracy was 0 6 degrees, and the distance between the needle tip, the target was 1 04 mm Experiments indicated that this robotic system is suitable for a variety of percutaneous clinical applications

}, keywords = {Biopsy, Computer-Assisted, Humans, Image Processing, Imaging, instrumentation, instrumentation/methods, Needle, Phantoms, Robotics, Surgery, Tomography, User-Computer Interface, X-Ray Computed}, doi = {10 1002/igs 10024}, url = {http://dx doi org/10 1002/igs 10024}, author = {Ken Masamune and Gabor Fichtinger and Alexandru Patriciu and Robert Susil and Russell H. Taylor and Louis Kavoussi and James Anderson and Ichiro Sakuma and Takeyoshi Dohi and Dan Stoianovici} }