| 1. |
- Bodin, Ingrid, et al.
(författare)
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Deterioration of intraoral recognition of shapes after treatment of oral and pharyngeal cancer.
- 2000
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Ingår i: Otolaryngology and head and neck surgery. - 0194-5998 .- 1097-6817. ; 122:4, s. 584-589
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Tidskriftsartikel (refereegranskat)abstract
- Thirty patients with diagnosed malignant tumors of the oral cavity or pharynx were tested in regards to intraoral shape recognition at 4 test occasions: before all treatment, after radiotherapy, 6 months after surgery, and 1 year after surgery. They were compared within groups as well as with a group of healthy reference individuals of the same age who underwent the same test procedure at a 2-month interval. The tumor itself did not influence the capability of shape recognition. The reference individuals demonstrated significantly better results on the second test occasion, which is known as a learning effect. Learning improvement was not seen in the patients whose second test occasions were after radiotherapy, implying an impediment amounting to the magnitude of the learning effect. At 6 months after surgery the patients' capabilities of shape recognition had deteriorated significantly with no difference between the oral cancer group and the pharyngeal cancer group. No spontaneous rehabilitation had taken place 1 year after surgery. The presence or absence of surgical lingual nerve damage did not influence the results. The nonoperated side does not compensate for the operated one. It is plausible that decreased oral sensory acuity in recognizing the shape of the bolus contributes to postoperative swallowing problems.
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| 2. |
- Nilsson, Tore, et al.
(författare)
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Virtual reality for simulation of radiographic projections: validation of projection geometry
- 2004
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Ingår i: Dento-Maxillo-Facial Radiology. - : British Institute of Radiology. - 0250-832X .- 1476-542X. ; 33:1, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To develop a software for virtual reality (VR) simulation of X-ray images based on perspective projections through a patient model derived from data from a CT examination and to evaluate the accuracy in the projection geometry obtained by the software. Methods: A VR software was developed on a personal computer, with models of a patient, an X-ray machine and a detector. The model of the patient was derived from data from a CT examination of a dry skull. Simulated radiographic images of the patient model could be rendered as perspective projections based on the relative positions between the models. The projection geometry of the software was validated by developing an artificial CT data set containing high attenuation points as objects to be imaged. The accuracy in projection geometry was evaluated in a systematic way. The distances between two dots, representing the projected test points in the simulated radiographic images, were measured. They were compared with theoretical calculations of the corresponding distances using traditional mathematical tools. Results: The difference between the simulated and calculated projected distances never exceeded 0.5 mm. The error in simulated projected distances was in most cases within 1%. No systematic errors were revealed. Conclusion: The software, developed for personal computers, can produce simulated X-ray images with high geometric accuracy based on perspective projections through a CT data set. The software can be used for simulation of radiographic examinations.
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