Vocal cord paralysis and paresis are debilitating conditions leading to difficulty with voice production. Medialization laryngoplasty is a surgical procedure designed to restore the voice in patients by implanting a uniquely configured structural support lateral to the paretic vocal fold through a window cut in the thyroid cartilage of the larynx. Currently, the surgeon relies on experience and intuition to place the implant in the desired location, therefore it is subject to a significant level of uncertainty. Window placement errors of up to 5mm in the vertical dimension are common in patients admitted for revision surgery. The failure rate of this procedure is as high as 24% even for experienced surgeons. An intraoperative image-guided system will help the surgeon to accurately place the implant by superimposing the CT data from the patient with the actual larynx of the patient during surgery.
One of the fundamental challenges in our system is to accurately register the preoperative 3D CT data to the intraoperative 3D surfaces of the patient. Our proposed image guided system will use the anatomical and geometric landmarks and points to register intraoperative 3D surface of thyroid cartilage to the preoperative 3D radiological data. The proposed approach has three phases. First, the laryngeal cartilage surface is segmented out from the preoperative 3D CT data. Second, the surface of the exposed laryngeal cartilage during the surgery is reconstructed intraop-eratively using stereo vision and structured light based surface scanning. Third, the two geometries are registered using ICP based shape matching. The proposed ap-proach has several advantages over alternative approaches: the combination of stereo vision and structured light surface scanning is capable of tracking the fiducial markers, reconstructing the surface of laryngeal cartilage and matching the preoperative and postoperative surfaces for registration purposes. The computer vision based approach can be applied to delicate areas like laryngeal cartilage with no danger of causing physical damage.

Current IR ship signature codes have some limitations in predicting ship IR signatures. They either model general BRDF while ignoring multi-reflections, or compute multi-reflection with simplified BRDF models. Much work has been done in simulating global illumination in computer graphics, especially in visual frequency domain. However, most global illumination algorithms do not guarantee the physical accuracy of the rendered result. In order to apply global illumination algorithms in IR signature prediction, several important problems need to be solved. The global illumination algorithm should be physically accurate, rather than visually acceptable. A general BRDF model could be incorporated into the rendering equation and multi-bounce computation. A surface patch needs to be modeled as both reflector and emitter. The sky and ground model could take the input from generalized radiance distribution samples from other simulators such as MODTRAN. The modeling method and predicted result need to be verified and validated. In order to apply global illumination algorithms to the infrared Ship signature prediction, we need to assess different rendering techniques in computer graphics domain for their applicability to Ship IR signature prediction. It is important to select the most appropriate rendering technique and evaluate its physical accuracy, general BRDF representation, light source modeling and Sky and ground modeling features. Based on the survey of current global illumination rendering techniques, we made a conclusion that RADIANCE, an importance based Monte Carlo Ray tracing method, is the best rendering technique applicable to IR Domain. We have made verification and modifications to RADIANCE method in modeling the surface patch as light source and reflector, incorporating general BRDF to the rendering equation and modeling sky and sea radiance distribution.

Prostate cryotherapy is a relatively new procedure for prostate cancer in which the prostate gland is treated in situ by freezing. The freezing and thawing process destroys the prostate glands, which are replaced by scar tissue following the procedure. This is accomplished by inserting several cylindrical cryoprobes into the gland under ultrasound guidance. Thermocouples are placed at strategic locations within and around the gland to monitor the formation of ice crystals around the cryoprobes which occurs when the cryoprobes are activated. The ability of a physician to deliver an efficacious freezing injury is largely dependent on clinical experience and the ability to create an area of treatment known as an ‘iceball’ that kills the target cancerous tissue without damaging surrounding tissues.
A prostate cryotherapy simulator has been developed to expedite the learning process associated with this technically demanding procedure. Three dimensional ultrasound images of the prostates from real patients are used. The physician can practice prostate cryotherapy in a clinically realistic manner by placing and operating the cryoprobes before actually treating a patient. During a clinical procedure the physician monitors the iceball growth on ultrasound and also uses the temperature measurements from the thermocouples to assess the extent of the freezing injury. A mathematical cryotherapy simulation with verified accuracy is used to determine the temperatures surrounding the cryoprobes during the procedure simulation. Changes that occur in the ultrasound image when ice forms in tissue have been accurately reproduced. Combining this visual feedback with the thermocouple readings, the physician can judge the extent of freeze injury in both tissues targeted for destruction and tissues that must remain unfrozen.
This simulator allows a physician to gain a skill set previously attainable only with clinical experience. The simulation is being incorporated into the training process by Endocare Inc., a leader in the development of cryotherapy technologies. The current training process consistsof a day of classroom instruction and the physician being proctored, on average, for their first six clinical cases. This is very inefficient from a cost perspective because of the need to provide an expert in cryotherapy as the proctor for each case. The simulator provides a physician an intuitive feel for the procedure and a solid understanding of how the freezing process will be visualized within the target tissue based upon placement and activation of the cryoprobes. Incorporation of the simulator into the training process is expected to reduce the number of cases that require oversight as the physician becomes comfortable with the procedure. Consequently, it is believed that this will result in a significant reduction of the cost associated with training.